Bubble power

HVDC

2010-02-07T08:15:00.001-08:00

High-voltage direct current

Introduction:

AC VS DC:

Ø AC won DC because AC can be transmitted with lower losses at high voltages.

Ø DC flows limited by voltage and resistance

Ø AC flows limited by resistance but also by the work needed to establish electric and magnetic fields

– Electric fields charge and discharge the insulation media surrounding the electric conductor

Ø Current “leaking” through cable insulation limits the useful length of cables for ac power transmission

– Magnetic fields surround the electric conductors and can magnetize magnetic materials and induce currents into conductors

Ø Energy required to build up the magnetic fields limits the useful length of overhead lines for power transmission

Ø DC is difficult to transform from a low voltage to a high voltage and back.

ü In fact, it is not possible to do electrically.

ü The coupling between ac and dc systems still uses transformers.

Limitations on long distance power transmission are

At ź wave length the voltage goes to infinity and the current goes to zero.

Solution: Detune antenna or use HVdc.

Long distance HVDC lines carrying hydroelectricity from Canada's Nelson river to this station where it is converted to AC for use in Winnipeg's local grid

A high-voltage, direct current (HVDC) electric power transmission system uses direct current for the bulk transmission of electrical power, in contrast with the more common alternating current systems. For long-distance distribution, HVDC systems are less expensive and suffer lower electrical losses. For shorter distances, the higher cost of DC conversion equipment compared to an AC system may be warranted where other benefits of direct current links are useful.
The modern form of HVDC transmission uses technology developed extensively in the 1930s in Sweden at ASEA. Early commercial installations included one in the Soviet Union in 1951 between Moscow and Kashira, and a 10-20 MW system between Gotland and mainland Sweden in 1954. The longest HVDC link in the world is currently the Inga-Shaba 1,700 km (1,100 mi) 600 MW link connecting the Inga Dam to the Shaba copper mine, in the Democratic Republic of Congo.

HVDC interconnections in western Europe - red are existing links, green are under construction, and blue are proposed. Many of these transfer power from renewable sources such as hydro and wind. For names, see also the annotated version.

High voltage transmission:

High voltage is used for transmission to reduce the energy lost in the resistance of the wires. For a given quantity of power transmitted, higher voltage reduces the transmission power loss. Power in a circuit is proportional to the current, but the power lost as heat in the wires is proportional to the square of the current. However, power is also proportional to voltage, so for a given power level, higher voltage can be traded off for lower current. Thus, the higher the voltage, the lower the power loss. Power loss can also be reduced by reducing resistance, commonly achieved by increasing the diameter of the conductor; but larger conductors are heavier and more expensive.
High voltages cannot be easily used in lighting and motors, and so transmission-level voltage must be reduced to values compatible with end-use equipment. The transformer, which only works with alternating current, is an efficient way to change voltages. The competition between the DC of Thomas Edison and the AC of Nikola Tesla and George Westinghouse was known as the War of Currents, with AC emerging victorious. Practical manipulation of DC voltages only became possible with the development of high power electronic devices such as mercury arc valves and later semiconductor devices, such as thyristors, insulated-gate bipolar transistors (IGBTs), high power capable MOSFETs (power metal–oxide–semiconductor field-effect transistors) and gate turn-off thyristors (GTOs).

History of HVDC transmission

HVDC in 1971: this 150 kV mercury arc valve converted AC hydropower voltage for transmission to distant cities from Manitoba Hydro generators.

The first long-distance transmission of electric power was demonstrated using direct current in 1882 at the Miesbach-Munich Power Transmission, but only 2.5 kW was transmitted. An early method of high-voltage DC transmission was developed by the Swiss engineer Rene Thury and his method was put into practice by 1889 in Italy by the Acquedotto de Ferrari-Galliera company. This system used series-connected motor-generator sets to increase voltage. Each set was insulated from ground and driven by insulated shafts from a prime mover. The line was operated in constant current mode, with up to 5,000 volts on each machine, some machines having double commutators to reduce the voltage on each commutator. This system transmitted 630 kW at 14 kV DC over a distance of 120 km The Moutiers-Lyon system transmitted 8,600 kW of hydroelectric power a distance of 124 miles, including 6 miles of underground cable. The system used eight series-connected generators with dual commutators for a total voltage of 150,000 volts between the poles, and ran from about 1906 until 1936. Fifteen Thury systems were in operation by 1913 Other Thury systems operating at up to 100 kV DC operated up to the 1930s, but the rotating machinery required high maintenance and had high energy loss. Various other electromechanical devices were tested during the first half of the 20th century with little commercial success
One conversion technique attempted for conversion of direct current from a high transmission voltage to lower utilization voltage was to charge series-connected batteries, then connect the batteries in parallel to serve distribution loads. While at least two commercial installations were tried around the turn of the 20th century, the technique was not generally useful owing to the limited capacity of batteries, difficulties in switching between series and parallel connections, and the inherent energy inefficiency of a battery charge/discharge cycle.
The grid controlled mercury arc valve became available for power transmission during the period 1920 to 1940. Starting in 1932, General Electric tested mercury-vapor valves and a 12 kV DC transmission line, which also served to convert 40 Hz generation to serve 60 Hz loads, at Mechanicville, New York. In 1941, a 60 MW, +/-200 kV, 115 km buried cable link was designed for the city of Berlin using mercury arc valves (Elbe-Project), but owing to the collapse of the German government in 1945 the project was never completed. The nominal justification for the project was that, during wartime, a buried cable would be less conspicuous as a bombing target. The equipment was moved to the Soviet Union and was put into service there
Introduction of the fully-static mercury arc valve to commercial service in 1954 marked the beginning of the modern era of HVDC transmission. A HVDC-connection was constructed by ASEA between the mainland of Sweden and the island Gotland. Mercury arc valves were common in systems designed up to 1975, but since then, HVDC systems use only solid-state devices. From 1975 to 2000, line-commutated converters (LCC) using thyristor valves were relied on. According to experts such as Vijay Sood, the next 25 years may well be dominated by force commutated converters, beginning with capacitor commutative converters (CCC) followed by self commutating converters which have largely supplanted LCC use Since use of semiconductor commutators, hundreds of HVDC sea-cables have been laid and worked with high reliability, usually better than 96% of the time.

Advantages of HVDC over AC transmission

The advantage of HVDC is the ability to transmit large amounts of power over long distances with lower capital costs and with lower losses than AC. Depending on voltage level and construction details, losses are quoted as about 3% per 1,000 km.^{[citation needed]} High-voltage direct current transmission allows efficient use of energy sources remote from load centers.

The Advantages of state-on-the-art HVDCplus Technology

Ø No need for active power transmission

Ø No require for reactive power load

Ø Active and reactive power can be controlled separately

Ø Connection to a weak or isolated AC system

Ø Multi-terminal hvdc -System can configured much simpler

Ø Smaller Space and Mva requirement for filters

Ø Transmission to an Island

In a number of applications HVDC is more effective than AC transmission. Examples include:

Ø Undersea cables, where high capacitance causes additional AC losses. (e.g., 250 km Baltic Cable between Sweden and Germany^] and the 600 km NorNed cable between Norway and the Netherlands)

Ø Endpoint-to-endpoint long-haul bulk power transmission without intermediate 'taps', for example, in remote areas

Ø Increasing the capacity of an existing power grid in situations where additional wires are difficult or expensive to install

Ø Power transmission and stabilization between unsynchronised AC distribution systems

Ø Connecting a remote generating plant to the distribution grid, for example Nelson River Bipole

Ø Stabilizing a predominantly AC power-grid, without increasing prospective short circuit current

Ø Reducing line cost. HVDC needs fewer conductors as there is no need to support multiple phases. Also, thinner conductors can be used since HVDC does not suffer from the skin effect

Ø Facilitate power transmission between different countries that use AC at differing voltages and/or frequencies

Ø Synchronize AC produced by renewable energy sources

Long undersea high voltage cables have a high electrical capacitance, since the conductors are surrounded by a relatively thin layer of insulation and a metal sheath. The geometry is that of a long co-axial capacitor. Where alternating current is used for cable transmission, this capacitance appears in parallel with load. Additional current must flow in the cable to charge the cable capacitance, which generates additional losses in the conductors of the cable. Additionally, there is a dielectric loss component in the material of the cable insulation, which consumes power.
When, however, direct current is used, the cable capacitance is only charged when the cable is first energized or when the voltage is changed; there is no steady-state additional current required. For a long AC undersea cable, the entire current-carrying capacity of the conductor could be used to supply the charging current alone. This limits the length of AC cables. DC cables have no such limitation. Although some DC leakage current continues to flow through the dielectric, this is very small compared to the cable rating.
HVDC can carry more power per conductor because, for a given power rating, the constant voltage in a DC line is lower than the peak voltage in an AC line. In AC power, the root mean square (RMS) voltage measurement is considered the standard, but RMS is only about 71% of the peak voltage. The peak voltage of AC determines the actual insulation thickness and conductor spacing. Because DC operates at a constant maximum voltage, this allows existing transmission line corridors with equally sized conductors and insulation to carry 100% more power into an area of high power consumption than AC, which can lower costs.
Because HVDC allows power transmission between unsynchronized AC distribution systems, it can help increase system stability, by preventing cascading failures from propagating from one part of a wider power transmission grid to another. Changes in load that would cause portions of an AC network to become unsynchronized and separate would not similarly affect a DC link, and the power flow through the DC link would tend to stabilize the AC network. The magnitude and direction of power flow through a DC link can be directly commanded, and changed as needed to support the AC networks at either end of the DC link. This has caused many power system operators to contemplate wider use of HVDC technology for its stability benefits alone.

Disadvantages

The disadvantages of HVDC are in conversion, switching, control, availability and maintenance.
The required static inverters are expensive and have limited overload capacity. At smaller transmission distances the losses in the static inverters may be bigger than in an AC transmission line. The cost of the inverters may not be offset by reductions in line construction cost and lower line loss. With two exceptions, all former mercury rectifiers worldwide have been dismantled or replaced by thyristor units. Pole 1 of the HVDC scheme between the North and South Islands of New Zealand still uses mercury arc rectifiers, as does Pole 1 of the Vancouver Island link in Canada.
In contrast to AC systems^{[citation needed]}, realizing multiterminal systems is complex, as is expanding existing schemes to multiterminal systems. Controlling power flow in a multiterminal DC system requires good communication between all the terminals; power flow must be actively regulated by the inverter control system instead of the inherent properties of the transmission line. Multi-terminal lines are rare. One is in operation at the Hydro Québec - New England transmission from Radisson to Sandy Pond Another example is the Sardinia-mainland Italy link which was modified in 1989 to also provide power to the island of Corsica.
HVDC is less reliable and has lower availability than AC systems, mainly due to the extra conversion equipment. Single pole systems have availability of about 98.5%, with about a third of the downtime unscheduled due to faults. Fault redundant bipole systems provide high availability for 50% of the link capacity, but availability of the full capacity is about 97% to 98%.
High voltage DC circuit breakers are difficult to build because some mechanism must be included in the circuit breaker to force current to zero, otherwise arcing and contact wear would be too great to allow reliable switching.
Operating a HVDC scheme requires many spare parts to be kept, often exclusively for one system as HVDC systems are less standardized than AC systems and technology changes faster.

Costs of high voltage DC transmission

Normally manufacturers such as AREVA, Siemens and ABB do not state specific cost information of a particular project since this is a commercial matter between the manufacturer and the client.
Costs vary widely depending on the specifics of the project such as power rating, circuit length, overhead vs. underwater route, land costs, and AC network improvements required at either terminal. A detailed evaluation of DC vs. AC cost may be required where there is no clear technical advantage to DC alone and only economics drives the selection.
However some practitioners have given out some information that can be reasonably well relied upon:

For an 8 GW 40 km link laid under the English Channel, the following are approximate primary equipment costs for a 2000 MW 500 kV bipolar conventional HVDC link (exclude way-leaving, on-shore reinforcement works, consenting, engineering, insurance, etc.)

Ø Converter stations ~£110M

Ø Subsea cable + installation ~£1M/km

So for an 8 GW capacity between England and France in four links, little is left over from £750M for the installed works. Add another £200–300M for the other works depending on additional onshore works required

Rectifying and inverting

Ø Components

Two of three thyristor valve stacks used for long distance transmission of power from Manitoba Hydro dams

Early static systems used mercury arc rectifiers, which were unreliable. Two HVDC systems using mercury arc rectifiers are still in service (As of 2008^[update]). The thyristor valve was first used in HVDC systems in the 1960s. The thyristor is a solid-state semiconductor device similar to the diode, but with an extra control terminal that is used to switch the device on at a particular instant during the AC cycle. The insulated-gate bipolar transistor (IGBT) is now also used and offers simpler control and reduced valve cost.
Because the voltages in HVDC systems, up to 800 kV in some cases, exceed the breakdown voltages of the semiconductor devices, HVDC converters are built using large numbers of semiconductors in series.
The low-voltage control circuits used to switch the thyristors on and off need to be isolated from the high voltages present on the transmission lines. This is usually done optically. In a hybrid control system, the low-voltage control electronics sends light pulses along optical fibres to the high-side control electronics. Another system, called direct light triggering, dispenses with the high-side electronics, instead using light pulses from the control electronics to switch light-triggered thyristors (LTTs).
A complete switching element is commonly referred to as a valve, irrespective of its construction.

Ø Rectifying and inverting systems

Rectification and inversion use essentially the same machinery. Many substations are set up in such a way that they can act as both rectifiers and inverters. At the AC end a set of transformers, often three physically separate single-phase transformers, isolate the station from the AC supply, to provide a local earth, and to ensure the correct eventual DC voltage. The output of these transformers is then connected to a bridge rectifier formed by a number of valves. The basic configuration uses six valves, connecting each of the three phases to each of the two DC rails. However, with a phase change only every sixty degrees, considerable harmonics remain on the DC rails.
An enhancement of this configuration uses 12 valves (often known as a twelve-pulse system). The AC is split into two separate three phase supplies before transformation. One of the sets of supplies is then configured to have a star (wye) secondary, the other a delta secondary, establishing a thirty degree phase difference between the two sets of three phases. With twelve valves connecting each of the two sets of three phases to the two DC rails, there is a phase change every 30 degrees, and harmonics are considerably reduced.
In addition to the conversion transformers and valve-sets, various passive resistive and reactive components help filter harmonics out of the DC rails.

Ø Configurations

A block diagram of a bipolar HVDC transmission system, between two stations designated A and B. AC - represents an alternating current network CON - represents a converter valve, either rectifier or inverter, TR represents a power transformer, DCTL is the direct-current transmission line conductor, DCL is a direct-current filter inductor, BP represents a bypass switch, and PM represent power factor correction and harmonic filter networks required at both ends of the link. The DC transmission line may be very short in a back-to-back link, or extend hundreds of miles (km) overhead, underground or underwater. One conductor of the DC line may be replaced by connections to earth ground.

Ø Monopole and earth return

In a common configuration, called monopole, one of the terminals of the rectifier is connected to earth ground. The other terminal, at a potential high above, or below, ground, is connected to a transmission line. The earthed terminal may or may not be connected to the corresponding connection at the inverting station by means of a second conductor.
If no metallic conductor is installed, current flows in the earth between the earth electrodes at the two stations. Therefore it is a type of single wire earth return. The issues surrounding earth-return current include:

ü Electrochemical corrosion of long buried metal objects such as pipelines

ü Underwater earth-return electrodes in seawater may produce chlorine or otherwise affect water chemistry.

ü An unbalanced current path may result in a net magnetic field, which can affect magnetic navigational compasses for ships passing over an underwater cable.

These effects can be eliminated with installation of a metallic return conductor between the two ends of the monopolar transmission line. Since one terminal of the converters is connected to earth, the return conductor need not be insulated for the full transmission voltage which makes it less costly than the high-voltage conductor. Use of a metallic return conductor is decided based on economic, technical and environmental factors
Modern monopolar systems for pure overhead lines carry typically 1,500 MW. If underground or underwater cables are used, the typical value is 600 MW.
Most monopolar systems are designed for future bipolar expansion. Transmission line towers may be designed to carry two conductors, even if only one is used initially for the monopole transmission system. The second conductor is either unused, used as electrode line or connected in parallel with the other (as in case of Baltic-Cable).

Bipolar

Bipolar system pylons of the Baltic-Cable-HVDC in Sweden

In bipolar transmission a pair of conductors is used, each at a high potential with respect to ground, in opposite polarity. Since these conductors must be insulated for the full voltage, transmission line cost is higher than a monopole with a return conductor. However, there are a number of advantages to bipolar transmission which can make it the attractive option.

Ø Under normal load, negligible earth-current flows, as in the case of monopolar transmission with a metallic earth-return. This reduces earth return loss and environmental effects.

Ø When a fault develops in a line, with earth return electrodes installed at each end of the line, approximately half the rated power can continue to flow using the earth as a return path, operating in monopolar mode.

Ø Since for a given total power rating each conductor of a bipolar line carries only half the current of monopolar lines, the cost of the second conductor is reduced compared to a monopolar line of the same rating.

Ø In very adverse terrain, the second conductor may be carried on an independent set of transmission towers, so that some power may continue to be transmitted even if one line is damaged.

A bipolar system may also be installed with a metallic earth return conductor.
Bipolar systems may carry as much as 3,200 MW at voltages of +/-600 kV. Submarine cable installations initially commissioned as a monopole may be upgraded with additional cables and operated as a bipole.

Back to back

A back-to-back station (or B2B for short) is a plant in which both static inverters and rectifiers are in the same area, usually in the same building. The length of the direct current line is kept as short as possible. HVDC back-to-back stations are used for

coupling of electricity mains of different frequency (as in Japan; and the GCC interconnection between UAE [50Hz] and Saudi Arabia [60Hz] under construction in ±2009-2011)
coupling two networks of the same nominal frequency but no fixed phase relationship (as until 1995/96 in Etzenricht, Dürnrohr and Vienna).
different frequency and phase number (for example, as a replacement for traction current converter plants)

The DC voltage in the intermediate circuit can be selected freely at HVDC back-to-back stations because of the short conductor length. The DC voltage is as low as possible, in order to build a small valve hall and to avoid series connections of valves. For this reason at HVDC back-to-back stations valves with the highest available current rating are used.

Systems with transmission lines

The most common configuration of an HVDC link is two inverter/rectifier stations connected by an overhead power line. This is also a configuration commonly used in connecting unsynchronised grids, in long-haul power transmission, and in undersea cables.
Multi-terminal HVDC links, connecting more than two points, are rare. The configuration of multiple terminals can be series, parallel, or hybrid (a mixture of series and parallel). Parallel configuration tends to be used for large capacity stations, and series for lower capacity stations. An example is the 2,000 MW Quebec - New England Transmission system opened in 1992, which is currently the largest multi-terminal HVDC system in the world.

Tripole: current-modulating control

A newly patented scheme (As of 2004^[update]) (Current modulation of direct current transmission lines) is intended for conversion of existing AC transmission lines to HVDC. Two of the three circuit conductors are operated as a bipole. The third conductor is used as a parallel monopole, equipped with reversing valves (or parallel valves connected in reverse polarity). The parallel monopole periodically relieves current from one pole or the other, switching polarity over a span of several minutes. The bipole conductors would be loaded to either 1.37 or 0.37 of their thermal limit, with the parallel monopole always carrying +/- 1 times its thermal limit current. The combined RMS heating effect is as if each of the conductors is always carrying 1.0 of its rated current. This allows heavier currents to be carried by the bipole conductors, and full use of the installed third conductor for energy transmission. High currents can be circulated through the line conductors even when load demand is low, for removal of ice.
Combined with the higher average power possible with a DC transmission line for the same line-to-ground voltage, a tripole conversion of an existing AC line could allow up to 80% more power to be transferred using the same transmission right-of-way, towers, and conductors. Some AC lines cannot be loaded to their thermal limit due to system stability, reliability, and reactive power concerns, which would not exist with an HVDC link.
The system would operate without earth-return current. Since a single failure of a pole converter or a conductor results in only a small loss of capacity and no earth-return current, reliability of this scheme would be high, with no time required for switching.
As of 2005^[update], no tri-pole conversions are in operation, although a transmission line in India has been converted to bipole HVDC.

Corona discharge

Corona discharge is the creation of ions in a fluid (such as air) by the presence of a strong electric field. Electrons are torn from neutral air, and either the positive ions or the electrons are attracted to the conductor, while the charged particles drift. This effect can cause considerable power loss, create audible and radio-frequency interference, generate toxic compounds such as oxides of nitrogen and ozone, and bring forth arcing.
Both AC and DC transmission lines can generate coronas, in the former case in the form of oscillating particles, in the latter a constant wind. Due to the space charge formed around the conductors, an HVDC system may have about half the loss per unit length of a high voltage AC system carrying the same amount of power. With monopolar transmission the choice of polarity of the energized conductor leads to a degree of control over the corona discharge. In particular, the polarity of the ions emitted can be controlled, which may have an environmental impact on particulate condensation. (particles of different polarities have a different mean-free path.) Negative coronas generate considerably more ozone than positive coronas, and generate it further downwind of the power line, creating the potential for health effects. The use of a positive voltage will reduce the ozone impacts of monopole HVDC power lines.

Applications

Ø Overview

The controllability of current-flow through HVDC rectifiers and inverters, their application in connecting unsynchronized networks, and their applications in efficient submarine cables mean that HVDC cables are often used at national boundaries for the exchange of power (in North America, HVDC connections divide much of Canada and the United States into several electrical regions that cross national borders, although the purpose of these connections is still to connect unsynchronized AC grids to each other). Offshore windfarms also require undersea cables, and their turbines are unsynchronized. In very long-distance connections between just two points, for example around the remote communities of Siberia, Canada, and the Scandinavian North, the decreased line-costs of HVDC also makes it the usual choice. Other applications have been noted throughout this article.

Ø AC network interconnections

AC transmission lines can only interconnect synchronized AC networks that oscillate at the same frequency and in phase. Many areas that wish to share power have unsynchronized networks. The power grids of the UK, Northern Europe and continental Europe are not united into a single synchronized network. Japan has 50 Hz and 60 Hz networks. Continental North America, while operating at 60 Hz throughout, is divided into regions which are unsynchronised: East, West, Texas, Quebec, and Alaska. Brazil and Paraguay, which share the enormous Itaipu hydroelectric plant, operate on 60 Hz and 50 Hz respectively. However, HVDC systems make it possible to interconnect unsynchronized AC networks, and also add the possibility of controlling AC voltage and reactive power flow.
A generator connected to a long AC transmission line may become unstable and fall out of synchronization with a distant AC power system. An HVDC transmission link may make it economically feasible to use remote generation sites. Wind farms located off-shore may use HVDC systems to collect power from multiple unsynchronized generators for transmission to the shore by an underwater cable.
In general, however, an HVDC power line will interconnect two AC regions of the power-distribution grid. Machinery to convert between AC and DC power adds a considerable cost in power transmission. The conversion from AC to DC is known as rectification, and from DC to AC as inversion. Above a certain break-even distance (about 50 km for submarine cables, and perhaps 600–800 km for overhead cables), the lower cost of the HVDC electrical conductors outweighs the cost of the electronics.
The conversion electronics also present an opportunity to effectively manage the power grid by means of controlling the magnitude and direction of power flow. An additional advantage of the existence of HVDC links, therefore, is potential increased stability in the transmission grid.

Ø Renewable electricity superhighways

A number of studies have highlighted the potential benefits of very wide area super grids based on HVDC since they can mitigate the effects of intermittency by averaging and smoothing the outputs of large numbers of geographically dispersed wind farms or solar farms. Czisch's study concludes that a grid covering the fringes of Europe could bring 100% renewable power (70% wind, 30% biomass) at close to today's prices. There has been debate over the technical feasibility of this proposal and the political risks involved in energy transmission across a large number of international borders. The construction of such green power superhighways is advocated in a white paper that was released by the American Wind Energy Association and the Solar Energy Industries Association
In January, the European Commission proposed €300 million to subsidize the development of HVDC links between Ireland, Britain, the Netherlands, Germany, Denmark, and Sweden, as part of a wider €1.2 billion package supporting links to offshore wind farms and cross-border interconnectors throughout Europe. Meanwhile the recently founded Union of the Mediterranean has embraced a Mediterranean Solar Plan to import large amounts of concentrating solar power into Europe from North Africa and the Middle East.

Ø Smaller scale use

The development of insulated gate bipolar transistors (IGBT) and gate turn-off thyristors (GTO) has made smaller HVDC systems economical. These may be installed in existing AC grids for their role in stabilizing power flow without the additional short-circuit current that would be produced by an additional AC transmission line. ABB manufacturer calls this concept "HVDC Light" and Siemens manufacturer calls a similar concept "HVDC PLUS" (Power Link Universal System). They have extended the use of HVDC down to blocks as small as a few tens of megawatts and lines as short as a few score kilometres of overhead line. The difference lies in the concept of the Voltage-Sourced Converter (VSC) technology whereas "HVDC Light" uses pulse width modulation and "HVDC PLUS" is based on multilevel switching.

Frequently asked questions:

ü Part of the Energy Solution?

HV is needed to transmit DC a long distance.
Semiconductor thyristors able to handle high currents (4,000 A) and block high voltages (up to 10 kV) were needed for the widespread adoption of HVDC.
Newer semiconductor VSC (voltage source converters), with transistors that can rapidly switch between two voltages, has allowed lower power DC.
VSC converter stations also are smaller and can be constructed as self-contained modules, reducing construction times and costs.

ü Why has HVDC taken off?

Long distance transmission increases competition in new wholesale electricity markets.
Long distance electricity trade, including across nations, allows arbitrage of price differences.
Contractual provision of transmission services demands more stable networks.
Bi-directional power transfers, often needed in new electricity markets, can be accommodated at lower cost using HVDC

ü Increased Benefits of Long-Distance Transmission

Electricity Costs and Prices Fluctuate Substantially

For equivalent transmission capacity, a DC line has lower construction costs than an AC line:
A double HVAC three-phase circuit with 6 conductors is needed to get the reliability of a two-pole DC link.
DC requires less insulation ceteris paribus.
For the same conductor, DC losses are less, so other costs, and generally final losses too, can be reduced.
An optimized DC link has smaller towers than an optimized AC link of equal capacity.

ü Relative Cost of AC versus DC

*Example Losses on Optimized Systems for 1200 MW

Typical tower structures and rights-of-way for alternative transmission systems of 2,000 MW capacity.

*Right-of-way for an AC Line designed to carry 2,000 MW is more than 70% wider than the right-of-way for a DC line of equivalent capacity.
*This is particularly important where land is expensive or permitting is a problem.
*HVDC “light” is now also transmitted via underground cable – the recently commissioned Murray-Link in

Australia

is 200 MW over 177 km.
*Can reduce land and environmental costs, but is more expensive per km than overhead line.

Case :1: costs per km basis
*Above costs are on a per km basis. The remaining costs also differ:
*The need to convert to and from AC implies the terminal stations for a DC line cost more.
*There are extra losses in DC/AC conversion relative to AC voltage transformation.
*Operation and maintenance costs are lower for an optimized HVDC than for an equal capacity optimized AC system.

Case :2 :cost with length
*The cost advantage of HVDC increases with the length, but decreases with the capacity, of a link.
*For both AC and DC, design characteristics trade-off fixed and variable costs, but losses are lower on the optimized DC link.
*The time profile of use of the link affects the cost of losses, since the MC of electricity fluctuates.
*Interest rates also affect the trade-off between capital and operating costs.

Case : 3:Typical Break-Even Distances

*HVDC is particularly suited to undersea transmission, where the losses from AC are large.
*First commercial HVDC link (Gotland 1 Sweden, in 1954) was an undersea one.
*Back-to-back converters are used to connect two AC systems with different frequencies – as in

Japan

– or two regions where AC is not synchronized – as in the

ü Special Applications of HVDC

Four major independent a synchronous networks, tied together only by DC interconnections:

1. Eastern Interconnected Network – all regions east of the Rockies except ERCOT and Quebec portion of the NPCC reliability council.

2. Quebec – part of the NPCC reliability council.

3. Texas – the ERCOT reliability council.

4. Western Interconnected Network – the WSCC reliability council.

*HVDC links can stabilize AC system frequencies and voltages, and help with unplanned outages.
*A DC link is asynchronous, and the conversion stations include frequency control functions.
*Changing DC power flow rapidly and independently of AC flows can help control reactive power.
*HVDC links designed to carry a maximum load cannot be overloaded by outage of parallel AC lines.

ü Special Applications (continued)

*Most early HVDC links were submarine cables where the cost advantage of DC is greatest.
*Others involved hydroelectric resources, since there is no practical alternative to long distance high voltage transmission of hydroelectric energy.
*Pacific DC tie installed in 1970 parallel to 2 AC circuits – system stabilization was a major issue.
*Square Butte link in N. Dakota (750 km, 500 MW, 250 kV) displaced transporting coal, with system stabilization a major ancillary benefit.

ü Some Early HVDC Projects

Itaipu,

Brazil

: 6,300 MW at ±600 kV DC.
*Two bipolar DC lines bring power generated at 50 Hz in the 12,600 MW Itaipu hydroelectric plant to the 60Hz network in São Paulo.
*Leyte-Luzon,

Philippines

: 350 kV monopolar, 440MW, 430 km overhead, 21 km submarine.
*Takes geothermal energy from Leyte to Luzon Assists with stabilizing the AC network.

ü Selected Recent Projects

Rihand-Delhi,

India

: 1,500 MW at ±500 kV .Existing 400 kV AC lines parallel the link.Takes power 814 km from a 3,000 MW coal-based thermal power station to Delhi.
HVDC halved the right-of-way needs, lowered transmission losses and increased the stability and controllability of the system.

ü Selected Projects (continued)

*Proposed Neptune Project: 1,000 km 1,200 MW submarine cable from Nova Scotia to Boston, New York city and NJ.
*Take natural gas energy to NY with less visual impact, while avoiding a NIMBY problem in NY and allowing old oil-fired plant in NY to be retired.
*Help improve network stability and reliability.
*The southern end has a summer peak demand, the northern end a winter one, so a bi-directional link allows savings from electricity trade.

ü Selected Projects (continued)

*Variable costs of an overhead HVDC link are less than the variable costs of pipeline gas.
*For 1,000–5,000 MW over 5,000 km pipeline gas is about 1.2–1.9 times more expensive (Arrillaga, 1998).
*Relative costs depend on the cost of land, and the price of gas among other factors.
*LNG also competes with HVDC for exploiting some gas reserves.

ü HVDC versus Gas Pipeline

*HVDC seems particularly suited to many renewable energy sources:
*Sources of supply (hydro, geothermal, wind, tidal) are often distant from demand centers.
*Wind turbines operating at variable speed generate power at different frequencies, requiring conversions to and from DC.
*Large hydro projects, for example, also often supply multiple transmission systems.

ü Renewable Energy & HVDC

*HVDC would appear to be particularly relevant for developing large scale solar electrical power.
*Major sources are low latitude, and high altitude deserts, and these tend to be remote from major demand centers.
*Photovoltaic cells also produce electricity as DC, eliminating the need to convert at source.

ü HVDC & Solar Power

Panels are assumed to have an efficiency of 14% at peak radiation and standard temperature reduced to approximately 13% efficiency due to system losses.
6 kWh/m2 light a day yields about 280 kWh/m2 of electricity a year for panels at 13% efficiency.
For average distances of 5,000 km, HVDC transmission losses would be about 25%.
About 20 panels each 30km×30km (18,000km2) would be needed to replace the 3,800 billion kWh of electricity produced in US in 2000.

First installed in

Japan

(Saijo) and

USA

(Hesperia) in the early 1980s.
Now more than 25 plants world-wide with peak power output from 300 kW to more than 3 MW
Most of the plants have fixed, tilted structures, without tracking.
These plants have proved easy to monitor and control and have achieved a 25% annual capacity factor even with modest downtime.

ü Grid-Connected PV Plants

Available sunlight does not vary greatly by season in the SW, while demand also peaks in summer.
Following map is Dec/July means over 10 years.

ü Seasonal Fluctuations

Daily Fluctuations

Capacity is needed to meet unexpected falls in output or demand surges.
Balance of system capital costs depend on peak load net of solar output.
Solar output is less peaked when panels track the sun, but this raises costs.
For SW of US, power could be sent west in morning hours, east in the afternoons.

Spatial and Temporal Arbitrage

High capacity HVDC (bi-directional) links between time zones, or different climates, can flatten peaks in solar output and in demand.
Only excess demands are traded as geographical differences in prices are eliminated through arbitrage.
Hydroelectric capacity and pumped storage allow electricity prices to be arbitraged over time.
Hydrogen produced through electrolysis might be another cost-effective way to store electricity.

Siberia has large coal and gas reserves and could produce 450-600 billion kWh of hydroelectricity annually, 45% of Japanese output in 1995.
A 1,800 km 11,000MW HVDC link would enable electricity to be exported from Siberia to

Japan

.
Siberia could also be linked to Alaska via HVDC.

Zaire

could produce 250–500 billion kWh of hydroelectricity annually to send to Europe (5-6,000 km) on a 30-60,000 MW link.
Hydroelectric projects on a similar scale have been proposed for

Canada

China

and

Brazil

Ø Transcontinental Energy Bridges

For transfers of 5,000 MW over 4,000 km, the optimum voltage rises to 1,000–1,100 kV.
Technological developments in converter stations would be required to handle these voltages.
Lower line losses would reduce the optimum voltage.
However, environmentalist opposition and unstable international relations may be the biggest obstacle to such grandiose schemes.

NOTE:
These informations are collected from different websites.

2010-01-14T09:58:00.000-08:00

“BUBBLE POWER”

(BASED ON: RENEWABLE AND NON-CONVENTIONAL SOURCE OF ELECTRICAL ENERGY)

SYNOPSIS:

1. ABSTRACT

2. INTRODUCTION

3. AN IDEA OF SONOFUSION

4. CONSTRUCTION & WORKING

5. FORMATION OF BUBBLES

6. FUSION REACTIONS TO PRODUCE ELECTRICITY

7. WHEN THE DREAM BECOMES REAL

8. CONCLUSION

ABSTRACT

For more than half a century, thermonuclear fusion held out the promise of cheap, clean and virtual limitless energy. In an experimental research, which is not yet concluded, it is found that deuterium, a material which is abundant in ocean water, when made to tiny bubbles, which can be imploded by using sound waves, can make hydrogen nuclei fuse. This phenomenon can be called as sonofusion. This is very much useful to produce bubble power. 1 km³ of sea water could, in principle, supply the entire world’s electrical energy need for several hundred years. At one day, it becomes a revolutionary new energy source.

INTRODUCTION

· Tiny bubbles imploded by sound waves can make Hydrogen nuclei – and may one day become a revolutionary new energy source.

· The bubbles violently collapse, can cause some of the deuterium nuclei to undergo fusion.

· Unleashed through a fusion reactor of some sort, the energy from 1 gm of deuterium, an isotope H₂, would be equivalent to that produced by burning 7000 liter of petrol.

· Deuterium is abundant in ocean water.

· We have yet to identify an economically viable fusion reactor technology that can consistently produce more energy that it consumes.

AN IDEA OF SONOFUSION

· Technically known as “Acoustic inertial confinement fusion”.

· This is derived from a related phenomenon called sonoluminescence.

· In sonoluminescence, a loud speaker is attached to liquid filled flask sends pressure waves through the fluids, existing the motion of tiny gas bubbles. They grow and collapse producing visible flashes of light that last less than 50 picoseconds.

· The excitation pressure higher than about 170 kpa would be required to dislodge the bubble from its stable position and disperse it in the liquid.

· About 20 years ago, researcher studying this light emitting bubble speculated that their interiors might reach such high temperature and pressure that they could bigger fusion.

CONSTRUCTION & WORKING

· It consists of cylindrical pynex glass flask 100 mm high and 65 mm in dia.

· A lead – zirconate – titanate ceramic piezoelectric crystal in the form of ring to the flasks outer surface. This act as a loudspeaker.

· Neutron generator is used, in order to make the bubbles artificially.

· Fill the flask with commercially available deuterated action, in which 99.9% of H₂ atoms in acetone molecule are deuterium.

· Which neuron is generated and collides during low pressure, the bubbles swells instantaneously - a process called cavitation.

· To grasp the magnitude of the growth, imagine that initial bubble growing to 100,000 times.

· As the pressure cycle rapidly reverses, liquid pushes the bubbles wall inward the tremendous force and they implode with great violence.

· This implosion create spherical shock wave within bubbles and travels inward cut high speed and significantly strengthen as they converge to their centers.

FORMATION OF BUBBLES

· To initiate sonofusion process, apply oscillating voltage with a frequency of about 20 KHz to piezoelectric ring.

· The construction and expansion of ring produce concentric pressure waves through the liquid.

· The wave becomes acoustic standing wave. This causes the center of flask region to oscillate between a 1500 Kpa (max) and –1500 Kpa (min).

· During positive pressure the liquid is impressed.

· When the pressure reaches lowest point, we fire a pulsed neutron generator of 14.1 Mev in a burst for 6 micro sec.

· Neutron collides with deuterium; in this collision the fast moving neutron may knock the atoms nuclei out of their molecule.

· The interaction between nuclei and molecule create heat and results in tiny bubbles of deuterated acetone vapour.

FUSION REACTIONS TO PRODUCE ELECTRICITY

· Each individual fusion reactions is very brief. It lasts only about a pico seconds and it is confined to a very small region. Think of it as “fusion sparks” rather than a fusion burn.

· As a result, the energy output is like a miniature stars within the bubble, the fusion reaction don’t melt the whole apparatus.

· To obtain something interesting interms of energy, the next step is to scale up the apparatus and make the fusion reactions self-sustaining. This is the greatest challenge not only for the sonofusion but also for all other fusion methods.

· The fusion produces high energy neutron that escape the plasma and hit a liquid filled blanket to generate vapour to drive a turbine and thus generate electricity.

· Yet tremendous challenges remain, such as controlling plasma in place while increasing temperature and pressure. It is a very unstable process that has proved difficult to control.

WHEN THE DREAM BECOMES REAL!!!

· It will have to overcome a number of challenges.

· This can be done by two adjacent sonofusion setups.

· Next it would be necessary to scale up the apparatus so it could produce more energy than it consumes.

· The heat produced by reaction is about 100 million degree centigrade controlling about 20,000 times that of the sun’s surface temperature.

· Yet tremendous challenges remain, such as controlling reactions while increase in temperature and pressure. It is very unstable process that has proved difficult to control. So, when the dream becomes real?

CONCLUSION

· Nevertheless, the Holy Grail of all fusion research is the development of a new, safe, environmentally friendly way to produce electrical energy.

· Fusion produces no green house gases and unlike conventional nuclear fission reactors, it produces no noxious radio active wastes that last for thousands of years.

· With the steady growth of world population and with economic progress in developing countries, average electricity consumption per person will increase significantly.

· Therefore, seeking new sources of energy isn’t just important, it is necessary.

· Much more research is required before it is clear whether sonofusion can become a new energy source.

Bubble Power

Tiny bubbles imploded by sound waves can make hydrogen nuclei fuse--and may one day become a revolutionary new energy source

BY RICHARD T. LAHEY JR., RUSI P. TALEYARKHAN, ROBERT I. NIGMATULIN // MAY 2005

For more than half a century, thermonuclear fusion has held out the promise of cheap, clean, and virtually limitless energy. Unleashed through a fusion reactor of some sort, the energy from 1 gram of deuterium, an isotope of hydrogen, would be equivalent to that produced by burning 7000 liters of gasoline. Deuterium is abundant in ocean water, and one cubic kilometer of seawater could, in principle, supply all the world's energy needs for several hundred years.

So why haven't we built any such reactors? Basically, because after spending billions of dollars on research, we have yet to identify an economically viable fusion-reactor technology that can consistently produce more energy than it consumes. Today, researchers are using enormous lasers or powerful magnetic fields to trigger limited fusion reactions among deuterium and other hydrogen isotopes. Results are promising and yet still modest--and so the challenge remains.

For several years our research groups--at Purdue University in West Lafayette, Ind.; Rensselaer Polytechnic Institute in Troy, N.Y.; and the Russian Academy of Sciences branch in Ufa--have been working on a new way to create fusion reactions. By applying sound waves to a deuterium-rich liquid, we create pressure oscillations that implode tiny bubbles filled with deuterium vapor. The bubbles' violent collapse can cause some of the deuterium nuclei to undergo fusion.

It is hard to imagine that mere sound waves can possibly produce in the bubbles, even briefly, the extreme temperatures and pressures created by the lasers or magnetic fields, which themselves replicate the interior conditions of stars like our sun, where fusion occurs steadily. Nevertheless, three years ago, we obtained strong evidence that such a process--now known as sonofusion--is indeed possible.

Since then, we have been working to improve and scale up our apparatus, investigating the possibility that it can produce a sizable surplus of energy. If this proves possible--and it's still a big "if"--sonofusion could become a revolutionary new energy source.

To explore this enticing possibility, early this year our research team joined forces with others to create the Acoustic Fusion Technology Energy Consortium, or AFTEC. Its five founders are Boston University; Impulse Devices Inc. in Grass Valley, Calif.; Purdue University; the University of Mississippi in Oxford; and the University of Washington in Seattle. Its goal is to promote the development of sonofusion and its related science and technology.

DEUTERIUM:

Hydrogen-2
Full table
General
Name, symbol	deuterium, ²H or D
Neutrons	1
Protons	1
Nuclide Data
Natural abundance	0.015%
Half-life	Stable
Isotope mass	2.01410178 u
Spin	1⁺
Excess energy	13,135.720±0.001 keV
Binding energy	2,224.52±0.20 keV

Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6,500 of hydrogen (~154 ppm). Deuterium thus accounts for approximately 0.015% (alternately, on a weight basis: 0.031%) of all naturally occurring hydrogen in the oceans on Earth (see VSMOW; the abundance changes slightly from one kind of natural water to another). Deuterium abundance on Jupiter is about2.25×10⁻⁵ (roughly 22 atoms in a million, or 15% of the terrestrial deuterium-to-hydrogen ratio);these ratios presumably reflect the early solar nebula ratios, and those after the Big Bang. However, other sources suggest a much higher abundance of e.g. 6×10⁻⁴ (6 atoms in10,000 or 0.06% atom basis).There is thought to be little deuterium in the interior of the Sunand other stars, as at temperatures there nuclear fusion reactions that consume deuterium happen much faster than the proton-proton reaction that creates deuterium. However, it continues to persist in the outer solar atmosphere at roughly the same concentration as in Jupiter.

The nucleus of deuterium, called a deuteron, contains one proton and one neutron, whereas the far more common hydrogen nucleus contains no neutron. The isotope name is formed from the Greek deuteros meaning "second", to denote the two particles composing the nucleus.

· 1 Differences between deuterium and common hydrogen (protium)

o 1.1 Chemical symbol

o 1.2 Natural abundance

· 2 Physical properties

· 3 Quantum properties

· 4 Nuclear properties

o 4.1 Deuterium as an isospin singlet

o 4.2 Approximated wavefunction of the deuteron

o 4.3 Magnetic and electric multipoles

o 4.4 Deuterium radius

· 5 Applications

o 5.1 Deuterium in nuclear reactors

o 5.2 Deuterium NMR spectroscopy

o 5.3 A stable isotope tracer

o 5.4 Neutron scattering scattering contrast properties

o 5.5 Nuclear resonance spectroscopy

· 6 History

o 6.1 Lighter element isotopes suspected

o 6.2 Deuterium predicted and finally detected

o 6.3 "Heavy water" experiments in World War II

o 6.4 Name

· 7 Data

· 8 Anti-deuterium

· 9 Pycnodeuterium

· 10 Ultra-dense deuterium

· 11 See also

· 12 References

· 13 External links

Differences between deuterium and common hydrogen (protium)

Chemical symbol

Deuterium is frequently represented by the chemical symbol D. Since it is an isotope of hydrogen with mass number 2, it is also represented by ²H. IUPAC allows both D and ²H, although ²H is preferred.The reason deuterium has a distinct chemical symbol may be its large mass difference with protium (¹H); deuterium has a mass of 2.014102 u, compared to the mean hydrogen atomic weight of 1.007947 u, and protium's mass of 1.007825 u. The isotope weight ratios within other chemical elements are largely insignificant in this regard, explaining the lack of unique isotope symbols elsewhere.^{[citation needed]}

Natural abundance

Deuterium occurs in trace amounts naturally as deuterium gas, written ²H₂ or D₂, but most natural occurrence in the universe is bonded with a typical ¹H atom, a gas called hydrogen deuteride (HD or ¹H²H).

The existence of deuterium on Earth, elsewhere in the solar system (as confirmed by planetary probes), and in the spectra of stars, is an important datum in cosmology. Gamma radiation from ordinary nuclear fusion dissociates deuterium into protons and neutrons, and there are no known natural processes other than the Big Bang nucleosynthesis, which might have produced deuterium at anything close to the observed natural abundance of deuterium (deuterium is produced by the rare cluster decay, and occasional absorption of naturally-occurring neutrons by light hydrogen, but these are trivial sources). The natural deuterium abundance seems to be a very similar fraction of hydrogen, wherever hydrogen is found. Thus, the existence of deuterium at a low but constant fraction in all hydrogen, is one of the arguments in favor of the Big Bang theory over the steady state theory of the universe. It is estimated that the abundances of deuterium have not evolved significantly since their production about 13.7 billion years ago.

The world's leading "producer" of deuterium (technically, merely enricher or concentrator of deuterium) was Canada, until 1997 when the last plant was shut down (see more in the heavy water article).

Canada

uses heavy water as a neutron moderator for the operation of the CANDU reactor design.

India

is now probably the world's largest concentrator of heavy water, also used in nuclear power reactors.

Physical properties

The physical properties of deuterium compounds can exhibit significant kinetic isotope effects and other physical and chemical property differences from the hydrogen analogs; for example, D₂O is more viscous than H₂O.Chemically, deuterium behaves similarly to ordinary hydrogen, but there are differences in bond energy and length for compounds of heavy hydrogen isotopes which are larger than the isotopic differences in any other element. Bonds involving deuterium and tritium are somewhat stronger than the corresponding bonds in hydrogen, and these differences are enough to make significant changes in biological reactions (see heavy water).

Deuterium can replace the normal hydrogen in water molecules to form heavy water (D₂O), which is about 10.6% denser than normal water (enough that ice made from it sinks in ordinary water). Heavy water is slightly toxic in eukaryotic animals, with 25% substitution of the body water causing cell division problems and sterility, and 50% substitution causing death by cytotoxic syndrome (bone marrow failure and gastrointestinal lining failure). Prokaryotic organisms, however, can survive and grow in pure heavy water (though they grow more slowly).Consumption of heavy water would not pose a health threat to humans, it was estimated that a 70&nbspkg person might drink 4.8 liters of heavy water without serious consequences. Small doses of heavy water (a few grams in humans, containing an amount of deuterium comparable to that normally present in the body) are routinely used as harmless metabolic tracers in humans and animals.

Quantum properties

The deuteron has spin +1 ("triplet") and is thus a boson. The NMR frequency of deuterium is significantly different from common light hydrogen.Infrared spectroscopy also easily differentiates many deuterated compounds, due to the large difference in IR absorption frequency seen in the vibration of a chemical bond containing deuterium, versus light hydrogen. The two stable isotopes of hydrogen can also be distinguished by using mass spectrometry.

The triplet deuteron nucleon barely is bound at E_B = 2.23 MeV, so all the higher energy states are not bound. The singlet deuteron is a virtual state, with a negative binding energy of ~60 keV. There is no such stable particle, but this virtual particle transiently exists during neutron-proton inelastic scattering, accounting for the unusually large neutron scattering cross-section of the proton.

Nuclear properties

Deuterium is one of only four stable nuclides with an odd number of protons and odd number of neutrons. (²H, ⁶Li, ¹⁰B, ¹⁴N; also, the long-lived radioactive nuclides ⁴⁰K, ⁵⁰V, ¹³⁸La, ^180mTa occur naturally.) Most odd-odd nuclei are unstable with respect to beta decay, because the decay products are even-even, and are therefore more strongly bound, due to nuclear pairing effects. Deuterium, however, benefits from having its proton and neutron coupled to a spin-1 state, which gives a stronger nuclear attraction; the corresponding spin-1 state does not exist in the two-neutron or two-proton system, due to the Pauli exclusion principle which would require one or the other identical particle with the same spin to have some other different quantum number, such as orbital angular momentum. But orbital angular momentum of either particle gives a lowerbinding energy for the system, primarily due to increasing distance of the particles in the steep gradient of the nuclear force. In both cases, this causes the diproton and dineutron nucleus to be unstable.

The proton and neutron making up deuterium can be dissociated through neutral current interactions with neutrinos. The cross section for this interaction is comparatively large, and deuterium was successfully used as a neutrino target in the Sudbury Neutrino Observatory experiment.

Deuterium as an isospin singlet

Due to the similarity in mass and nuclear properties between the proton and neutron, they are sometimes considered as two symmetric types of the same object, a nucleon. While only the proton has an electric charge, this is often negligible due of the weakness of the electromagnetic interaction relative to the strong nuclear interaction. The symmetry relating the proton and neutron is known as isospin and denoted I (or sometimes T).

Isospin is an SU(2) symmetry, like ordinary spin, so is completely analogous to it. The proton and neutron form an isospin doublet, with a"down" state (↓) being a neutron, and an "up" state (↑) being a proton.

A pair of nucleons can either be in an antisymmetric state of isospin called singlet, or in a symmetric state called triplet. In terms of the "down" state and "up" state, the singlet is

This is a nucleus with one proton and one neutron, i.e. a deuterium nucleus. The triplet is

and thus consists of three types of nuclei, which are supposed to be symmetric: a deuterium nucleus (actually a highly excited state of it), a nucleus with two protons, and a nucleus with two neutrons. The latter two nuclei are not stable or nearly stable, and therefore so is this type of deuterium (meaning that it is indeed a highly excited state of deuterium).

Approximated wavefunction of the deuteron

The deuteron wavefunction must be antisymmetric if the isospin representation is used (since a proton and a neutron are not identical particles, the wavefunction need not be antisymmetric in general). Apart from their isospin, the two nucleons also have spin and spatial distributions of their wavefunction. The latter is symmetric if the deuteron is symmetric under parity (i.e. have an "even" or "positive" parity), and antisymmetric if the deuteron is antisymmetric under parity (i.e. have an "odd" or "negative" parity). The parity is fully determined by the total orbital angular momentum of the two nucleons: if it is even then the parity is even (positive), and if it is odd then the parity is odd (negative).

The deuteron, being an isospin singlet, is antisymmetric under nucleons exchange due to isospin, and therefore must be symmetric under the double exchange of their spin and location. Therefore it can be in either of the following two different states:

§ Symmetric spin and symmetric under parity. In this case, the exchange of the two nucleons will multiply the deuterium wavefunction by (-1) from isospin exchange, (+1) from spin exchange and (+1) from parity (location exchange), for a total of (-1) as needed for antisymmetry.

§ Antisymmetric spin and antisymmetric under parity. In this case, the exchange of the two nucleons will multiply the deuterium wavefunction by (-1) from isospin exchange, (-1) from spin exchange and (-1) from parity (location exchange), again for a total of (-1) as needed for antisymmetry.

In the first case the deuteron is a spin triplet, so that its total spin s is 1. It also has an even parity and therefore even orbital angular momentuml ; The lower its orbital angular momentum, the lower its energy. Therefore the lowest possible energy state has s = 1, l = 0.

In the second case the deuteron is a spin singlet, so that its total spin s is 0. It also has an odd parity and therefore odd orbital angular momentum l. Therefore the lowest possible energy state has s = 0, l = 1.

Since s = 1 gives a stronger nuclear attraction, the deuterium ground state is in the s =1, l = 0 state.

The same considerations lead to the possible states of an isospin triplet having s = 0, l = even or s = 1, l = odd. Thus the state of lowest energy has s = 1, l = 1, higher than that of the isospin singlet.

The analysis just given is in fact only approximate, both because isospin is not an exact symmetry, and more importantly because the strong nuclear interaction between the two nucleons is related to angular momentum in spin-orbit interaction that mixes different s and l states. That is, s and l are not constant in time (they do not commute with the Hamiltonian), and over time a state such as s = 1, l = 0 may become a state of s = 1, l = 2. Parity is still constant in time so these do not mix with odd l states (such as s = 0, l = 1). Therefore the quantum state of the deuterium is a superposition (a linear combination) of the s = 1, l = 0 state and the s = 1, l = 2 state, even though the first component is much bigger. Since the total angular momentum j is also a good quantum number (it is a constant in time), both components must have the same j, and therefore j = 1. This is the total spin of the deuterium nucleus.

To summarize, the deuterium nucleus is antisymmetric in terms of isospin, and has spin 1 and even (+1) parity. The relative angular momentum of its nucleons l is not well defined, and the deuteron is a superposition of mostly l = 0 with some l = 2.

Magnetic and electric multipoles

In order to find theoretically the deuterium magnetic dipole moment µ, one uses the formula for a nuclear magnetic moment

with

g^(l) and g^(s) are g-factors of the nucleons.

Since the proton and neutron have different values for g^(l) and g^(s), one must separate their contributions. Each gets half of the deuterium orbital angular momentum and spin . One arrives at

where subscripts p and n stand for the proton and neutron, and g^(l)_n = 0.

By using the same identities as here and using the value g^(l)_p = 1 μ_N, we arrive at the following result, in nuclear magneton units

For the s = 1, l = 0 state (j = 1), we obtain

For the s = 1, l = 2 state (j = 1), we obtain

The measured value of the deuterium magnetic dipole moment, is 0.857 μ_N. This suggests that the state of the deuterium is indeed only approximately s = 1, l = 0 state, and is actually a linear combination of (mostly) this state with s = 1, l = 2 state.

The electric dipole is zero as usual.

The measured electric quadropole of the deuterium is 0.2859 e·fm². While the order of magnitude is reasonable, since the deuterium radius is of order of 1 femtometer (see below) and its electric charge is e, the above model does not suffice for its computation. More specifically, theelectric quadrupole does not get a contribution from the l =0 state (which is the dominant one) and does get a contribution from a term mixing the l =0 and the l =2 states, because the electric quadrupole operator does not commute with angular momentum. The latter contribution is dominant in the absence of a pure l = 0 contribution, but cannot be calculated without knowing the exact spatial form of the nucleonswavefunction inside the deuterium.

Higher magnetic and electric multipole moments cannot be calculated by the above model, for similar reasons.

Deuterium radius

Further information: Nuclear size

The square root of the average squared radius of the deuterium, measured experimentally, is

Applications

Emission spectrum of an ultraviolet deuterium arc lamp.

Deuterium has a number of commercial and scientific uses. These include:

Deuterium in nuclear reactors

Deuterium is useful in nuclear fusion reactions, especially in combination with tritium, because of the large reaction rate (or nuclear cross section) and highenergy yield of the D–T reaction. There is an even higher-yield D–³He fusion reaction, though the breakeven point of D–³He is higher than that of most other fusion reactions; together with the scarcity of ³He, this makes it implausible as a practical power source until at least D–T and D–D fusion reactions have been performed on a commercial scale.

Deuterium is used in heavy water moderated fission reactors, usually as liquid D₂O, to slow neutrons without high neutron absorption of ordinary hydrogen.

Deuterium NMR spectroscopy

Deuterium NMR spectra are especially informative in the solid state because of its relatively small quadrupole moment in comparison with those of bigger quadrupolar nuclei such as chlorine-35, for example.

A stable isotope tracer

In chemistry, biochemistry and environmental sciences, deuterium is used as a non-radioactive, stable isotopic tracer. In chemical reactionsand metabolic pathways, deuterium behaves similarly to ordinary hydrogen, but it can be distinguished from ordinary hydrogen by its mass, using mass spectrometry or infrared spectrometry. Deuterium can be detected by femtosecond infrared spectroscopy, since the mass difference drastically affects the frequency of molecular vibrations; deuterium-carbon bond vibrations are found in locations free of other signals.

Measurements of small variations in the natural abundances of deuterium, along with those of the stable heavy oxygen isotopes ¹⁷O and ¹⁸O, are of importance in hydrology, to trace the geographic origin of Earth's waters. The heavy isotopes of hydrogen and oxygen in rainwater (so-called meteoric water) are enriched as a function of the environmental temperature of the region in which the precipitation falls (and thus enrichment is related to mean latitude). The relative enrichment of the heavy isotopes in rainwater (as referenced to mean ocean water), when plotted against temperature falls predictably along a line called the global meteoric water line (GMWL). This plot allows samples of precipitation-originated water to be identified along with general information about the climate in which it originated. Evaporative and other processes in bodies of water, and also ground water processes, also differentially alter the ratios of heavy hydrogen and oxygen isotopes in fresh and salt waters, in characteristic and often regionally-distinctive ways.^[11]

Neutron scattering scattering contrast properties

Neutron scattering techniques particularly profit from availability of deuterated samples: The H and D cross sections are very distinct and different in sign, which allows contrast variation in such experiments. Further, a nuisance problem of ordinary hydrogen is its large incoherent neutron cross section, which is nil for D and delivers much clearer signals in deuterated samples. Hydrogen occurs in all materials of organic chemistry and life science, but cannot be seen by X-ray diffraction methods. Hydrogen can be seen by neutron diffraction and scattering, which makes neutron scattering, together with a modern deuteration facility, indispensable for many studies of macromolecules in biology and many other areas.

Nuclear resonance spectroscopy

Deuterium is useful in hydrogen nuclear magnetic resonance spectroscopy (proton NMR). NMR ordinarily requires compounds of interest to be analyzed as dissolved in solution. Because of deuterium's nuclear spin properties which differ from the light hydrogen usually present in organic molecules, NMR spectra of hydrogen/protium are highly differentiable from that of deuterium, and in practice deuterium is not "seen" by an NMR instrument tuned to light-hydrogen. Deuterated solvents (including heavy water, but also compounds like deuterated chloroform, CDCl₃) are therefore routinely used in NMR spectroscopy, in order to allow only the light-hydrogen spectra of the compound of interest to be measured, without solvent-signal interference.

History

Lighter element isotopes suspected

The existence of nonradioactive isotopes of lighter elements had been suspected in studies of neon as early as 1913, and proven by mass spectroscopy of light elements in 1920. The prevailing theory at the time, however, was that the isotopes were due to the existence of differing numbers of "nuclear electrons" in different atoms of an element. It was expected that hydrogen, with a measured average atomic mass very close to 1 u, and a nucleus thought to be composed of a single proton (a known particle), could not contain nuclear electrons, and thus could have no heavy isotopes.

Deuterium predicted and finally detected

Deuterium was predicted in 1926 by Walter Russell, using his "spiral" periodic table. It was first detected spectroscopically in late 1931 byHarold Urey, a chemist at Columbia University. Urey's collaborator, Ferdinand Brickwedde, distilled five liters of cryogenically-produced liquid hydrogen to 1 mL of liquid, using the low-temperature physics laboratory that had recently been established at the National Bureau of Standards in Washington, D.C. (now the National Institute of Standards and Technology). This concentrated the fraction of the mass-2 isotope of hydrogen to a degree that made its spectroscopic identification unambiguous; Urey called the isotope "deuterium" from the Greek and Latinwords for "two". The amount inferred for normal abundance of this heavy isotope was so small (only about 1 atom in 6400 hydrogen atoms in ocean water) that it had not noticeably affected previous measurements of (average) hydrogen atomic mass. Urey was also able to concentrate water to show partial enrichment of deuterium. Gilbert Newton Lewis prepared the first samples of pure heavy water in 1933. The discovery of deuterium, coming before the discovery of the neutron in 1932, was an experimental shock to theory, and after the neutron was reported, deuterium won Urey the Nobel Prize in chemistry in 1934.

"Heavy water" experiments in World War II

Shortly before the war, Hans von Halban and Lew Kowarski moved their research on neutron moderation from France to England, smuggling the entire global supply of heavy water (which had been made in Norway) across in twenty-six steel drums.

During World War II, Nazi Germany was known to be conducting experiments using heavy water as moderator for a nuclear reactor design. (Heavy water is water in which the hydrogen is deuterium.) Such experiments were a source of concern because they might allow them to produce plutonium for an atomic bomb. Ultimately it led to the Allied operation called the "Norwegian heavy water sabotage," the purpose of which was to destroy the Vemork deuterium production/enrichment facility in Norway. At the time this was considered important to the potential progress of the war.

After World War II ended, the Allies discovered that Germany was not putting as much serious effort into the program as had been previously thought.^{[citation needed]} The Germans had completed only a small, partly-built experimental reactor (which had been hidden away). By the end of the war, the Germans did not even have a fifth of the amount of heavy water needed to run the reactor, partially due to the Norwegian heavy water sabotage operation.^{[citation needed]} However, even had the Germans succeeded in getting a reactor operational (as the U.S. did with a graphite reactor in late 1942), they would still have been at least several years away from development of an atomic bomb with maximal effort. The engineering process, even with maximal effort and funding, required about two and a half years (from first critical reactor to bomb) in both the

U.S.

and U.S.S.R, for example.

Name

Urey called the molecule "deuterium", from the Greek deuteros (second), and the nucleus to be called "deuteron" or "deuton". The molecules were traditionally given the name that its discoverer decided, but some British chemists, like Ernest Rutherford, wanted the molecule to be called "diplogen", from the Greek diploos (double), and the nucleus to be called diplon. The British magazine Nature also published a letter where only the denomination "diplogen" was used, perhaps annunciating that British could prefer that name over the name given by its discoverer. Urey and his two co-discoverers sent a letter to Nature saying that they had already considered that name and they had rejected it because "The compound NH1H2/2 would be called di-diplogen mono-hydrogen nitride", which would repeat the syllable "di." They also said that the British seemed to object on the basis that "neutron" and "deuton" could be confused with each other, and he points out that American workers were using the terms and they didn't seem to be having any such confusion.

Data

§ Density: 0.180 kg/m³ at STP (0 °C, 101.325 kPa).

§ Atomic weight: 2.01355321270 u.

§ Mean abundance in ocean water (see VSMOW) about 0.0156 % of H atoms = 1/6400 H atoms.

Data at approximately 18 K for D₂ (triple point):

§ Density:

§ Liquid: 162.4 kg/m³

§ Gas: 0.452 kg/m³

§ Viscosity: 12.6 µPa·s at 300 K (gas phase)

§ Specific heat capacity at constant pressure c_p:

§ Solid: 2,950 J/(kg·K)

§ Gas: 5,200 J/(kg·K)

Anti-deuterium:

An antideuteron is the antiparticle of the nucleus of deuterium, consisting of an antiproton and an antineutron. The antideuteron was first produced in 1965 at the Proton Synchrotron at CERN^[14] and the Alternating Gradient Synchrotron at Brookhaven National Laboratory.A complete atom, with a positron orbiting the nucleus, would be called antideuterium, but as of 2005 antideuterium has not yet been created. The proposed symbol for antideuterium is D, that is, D with an overbar.

Pycnodeuterium :

Deuterium atoms can be absorbed into a palladium (Pd) lattice. They are effectively solidified as an ultrahigh density deuterium lump (Pycnodeuterium) inside each octahedral space within the unit cell of the palladium host lattice. Some believe it may be possible to use this as a nuclear fuel in cold fusion. However, cold fusion by this mechanism has not been generally accepted by the scientific community.

Ultra-dense deuterium

The existence of ultra-dense deuterium is suggested by experimental results reported by researchers at the University of Gothenburg. If its existence is confirmed, this material would be a million times more dense than regular deuterium, denser than the core of the Sun. The researchers suggest that this ultra-dense form of deuterium will enable laser-induced fusion to occur more easily.

The researchers have reported the production of minute amounts of ultra-dense deuterium in two recent publications. Ultra-dense deuterium would be by far the most dense material ever produced by man - one cubic centimetre would have a mass of 140 kilograms.

sonoluminescence: Bubble power

When a gas bubble in a liquid is excited by ultrasonic acoustic waves, it can
emit short flashes of light suggestive of extreme temperatures inside the bubble.
These flashes of light, known as 'sonoluminescence', occur as the bubble
implodes, or cavitates. Now Didenko and Suslick show that chemical reactions
occur during cavitation of a single, isolated bubble, and they go on to determine
the yield of photons, radicals and ions formed.

Devastating Bubble Power

The effects of underwater explosions, such as that generated by torpedoes or mines, are much more devastating than a similar explosion in air. Over the last decade a numerical code on underwater explosion and bubble dynamics has been jointly developed by faculties at the Department of Mechanical Engineering, NUS, and researchers from the Institute of High Performance Computing (IHPC), to understand better the underwater explosion phenomenon and its devastating effects.

A bubble forms at the epicentre of the explosion , which grows very rapidly to its maximum volume. It then collapses rapidly while moving towards the plate. At the same time, a high-speed jet is formed, propagating though the collapsing bubble. A very high pressure is generated on the plate as the jet impacts on the other side of the bubble, while the bubble continues to contract until it reaches its minimum volume. then bubble starts re-expanding again and the process repeats itself despite the much lower expansion and implosion energies.
A bubble forms at the epicentre of the explosion and grows very rapidly and then collapses. In the final phase of the collapse, a high-speed jet is formed, which can easily cut through the ship body.

The potential devastating effect of an underwater explosion on a ship .At the moment of explosion, a shock wave propagates through the water (in a few milliseconds). This shock wave will have a first damaging impact on the ship body.This figure also shows the creation of a bubble at the epicentre of the explosion. The high pressure gas bubble expands very rapidly. At the same time, the ship will bend upwards and its hull is weakened .After reaching its maximum volume, the bubble collapses eventually due to the effect of inertia. The pressure will now be lower than the surrounding reference pressure, causing the ship body to bend downwards .During this collapse phase the bubble is attracted to the ship body. In the final phase of the collapse, a high-speed jet is formed. This high-speed jet can easily cut through the ship body. This mechanism has been identified as being a second cause of damage (and probably even the most devastating one) that appears during an underwater explosion.After the bubble has reached its second minimum a similar cycle can begin. However, as the bubble has lost much of its energy, the following oscillations will not have as great destructive power in general.
Some small-scale experiments have been carried out and were compared successfully with the obtained numerical results like in Figure 1.The validated code can be applied to other relevant engineering problems, for example, in cavitation on ship propellers (where tiny vapour bubbles can cause a lot of damage on these propellers) or in medical applications. The method of imploding micro-bubbles with ultrasound in biological flows to remove kidney stone or growth is also based
on the same physics, but on a much smaller scale of course.

How It Works: Bubble Power

When we read that physicists were dropping speakers into water to try and kick start cold fusion reactions, which could supply endless clean energy, we thought that they must have gone barmy. That's because we'd never heard of sonoluminescence, the mysterious phenomenon where sound makes bubbles all-powerful. B. James McCullum and Stuart Smith get to grips with some weird science.

We all know the legend of the opera diva hitting a high note and shattering glass, but could she also make the glass burst into flames or even cause two hydrogen nuclei in the contents of the glass to combine, providing enough energy to power a small country? It might not be as farfetched as it sounds.

Back in the 1930's, a pair of scientists found out that sending ultrasonic waves into a liquid could expose photographic plates – sound energy was being turned into light. The phenomenon known as sonoluminescence was born.

Although no one is quite sure how sonoluminescence actually works, everyone agrees that when an ultrasonic generator (read really powerful speaker) is put in liquid, it can create tiny glowing bubbles.

Everybody also agrees that sound waves advance as patterns of positive and negative pressure. So the traditional wisdom about sonoluminescence has it that, when the negative pressure portion of a sound wave passes through a bubble in a liquid, it causes that bubble to swell in size by several orders of magnitude. When the subsequent positive pressure portion of the sound wave approaches, that large bubble is forced to shrink rapidly by a process calledacoustic cavitation. In this theory, the collapse results in all the energy that went in to the expansion of the bubble being compressed in to a very small area. In other words, a proportionately huge amount of energy gets focused into a very tiny package. As a result the small amount of gas trapped inside the bubble is heated to absurdly hot temperatures, causing it to glow.

Not all scientists buy this explanation though – some physicists who study bubbles (and yes there are such things) believe that a bubble has to remain perfectly mathematically spherical in order for acoustic cavitation to occur, and they argue that nature just doesn't work that way. One of the more prominent competing theories states that super-fast jets of liquid shoot across the bubble and actually fracture the water molecules on the other side (yes, you can break a molecule like this). The break causes a release of energy and hence light. You can witness a similar effect from breaking or even simply rubbing any number of crystals – in this case it is called triboluminescence (rubbing) orfractoluminescence (breaking). It results from charges within molecule being forced apart, and then combining back together, which ionizes the air and causes a flash.

Some researchers have even speculated that sonoluminescence may be a manifestation of the proposed infinite energy of a vacuum, commonly referred to in modern science fiction as zero point energy. If this is the case, it may be due to an exotic phenomenon called the Casimir Effect. According to this theory, substances in a vacuum moving closer together eventually get attracted to each other because there is "more of a vacuum" between them then elsewhere in the vacuum. The resulting motion may result in the change of "vacuum" or "zero point" energy to real energy and hence the spark. Since, in this scenario, you’re producing something (energy) from nothing (a vacuum), theoretically the amount of energy we could produce from a system like this is limitless.

The real reason why anybody cares about lights created from sound, however, is because some have speculated that if the acoustic cavitation mechanism holds true, then temperatures inside the bubble may reach 2 million kelvins – hot enough to produce a cold fusion reaction which could provide enough environmentally safe energy to power everything for, well, ever. Unfortunately, it appears that the real temperature may be closer to 10,000 degrees, which is only as hot as the surface of the sun. Whilst not hot enough to spark cold fusion, it would still make a hell of a grill.

So can you yell at water and make is light up? Not exactly. In fact, the authors submerged a 12 megahertz medical ultrasound probe in a coffee pot of water this morning and got nothing. It takes a bit of effort. On the other hand, fractoluminescence, which is also fairly cool, is easy to demonstrate. A Wint O Green flavor Lifesaver brand candy is the ideal equipment for this experiment, but sugar cubes or certain types of quartz will work as well. After retiring to a dark room, take a pair of pliers (or even a hammer) and crush the candy. You should see flashes of a bluish light. The benefit to the lifesaver over other crystals is that it also contains oil of wintergreen, which will fluoresce, accentuating the effect.

Bubble power

Article Abstract:

By applying sound waves to a deuterium-rich liquid, pressure oscillations are created that implode tiny bubbles filled with deuterium vapor. The bubbles' violent collapse can cause some of the deuterium nuclei to undergo fusion that is known as 'Sonofusion'. It could become a new source of energy in the future.

sonofusion

Bubble fusion or sonofusion is the common name for a nuclear fusion reaction hypothesized to occur during sonoluminescence, an extreme form of acoustic cavitation; officially, this reaction is termed acoustic inertial confinement fusion (AICF) since the inertia of the collapsing bubble wall confines the energy, causing a rise in temperature. The high temperatures producible through sonoluminescence raises the possibility that it might be a means to achieve thermonuclear fusion.^[1]

[hide]

· 1 Original experiments

· 2 Oak Ridge replication

· 3 Subsequent claims of replication

· 4 Doubts prompt investigation

· 5 Nature's suggestion of misuse of funds ill-founded?

o 5.1 Ethical dimension

· 6 See also

· 7 References

· 8 External links

o 8.1 Repositories

o 8.2 News

Original experiments

The earliest reference to a sonofusion-type reaction is in US patent 4,333,796 filed by Hugh Flynn in 1978.

Rusi P. Taleyarkhan (ORNL) and colleagues reported in the March 8, 2002, issue of the peer-reviewed journal Science, that acoustic cavitation experiments conducted with deuterated acetone (Template:carbon Template:deuterium Template:oxygen) show measurements of tritium andneutron output that are consistent with fusion; in addition the neutron emission was claimed to be coincident with the sonoluminescence pulse.

Shock wave simulations seem to indicate that the temperatures inside the collapsing bubbles may reach up to 10 megakelvins — as hot as the center of the sun. None of the above measurements have been confirmed by a group outside of Taleyarkhan's and are highly debated, recalling the 1989 cold fusion controversy.However, New Energy Times has reported a replication by an unrelated group at a university in Texas. (Researcher Edward Forringer works at LeTourneau University, a small evangelical Christian school.) Although the apparatus operates in a room temperature environment, this is not cold fusion (as it is commonly termed in the popular press), as the claimed nuclear reactions would be occurring at the very high temperatures in the core of the imploding bubbles.

The researchers used a pulse of neutrons in order to nucleate (i.e., "seed") the tiny bubbles, whereas most previous experiments start with small air bubbles already in the liquid. Using this new method, the team was able to produce stable bubbles that could expand to nearly a millimeter in radius before collapsing. In this way, the researchers stated, they were able to create the conditions necessary to produce very high pressures and temperatures. The sensitivity of the fusion rate to temperature, which is in turn a function of how small the bubbles get when they collapse, in combination with the likely sensitivity of the latter to fine experimental details, may account for the fact that some research workers have claimed to see an effect, while others have not.

Taleyarkhan et al. also prepared identical experiments in non-deuterated (normal) acetone and failed to observe neutron emission or tritium production. Taleyarkhan got the idea of bubble fusion from his friend Dr. Mark Embrechts after a friendly post-dinner chat in 1995.

Oak Ridge replication

These experiments were repeated at Oak Ridge National Laboratory by D. Shapira and M. J. Saltmarsh with more sophisticated neutron detection equipment and they reported that the neutron release was consistent with random coincidence A rebuttal by Taleyarkhan and the other authors of the original report claimed that the Shapira and Saltmarsh report failed to account for significant differences in experimental setup, including over an inch of shielding between the neutron detector and the sonoluminescing acetone. Taleyarkhan et al. report that when these differences are properly accounted for, the Shapira and Saltmarsh results are consistent with fusion.^[unverified]

In addition, Galonsky has shown that by Taleyarkhan's own detector calibration the observed neutrons are too high in energy to be from a d-d fusion reaction. In a rebuttal comment, Taleyarkhan says the energy is "reasonably close" to that which is expected.

In February 2005, the BBC documentary series Horizon commissioned a collaboration between Seth Putterman and Ken Suslick (two leading sonoluminescence researchers) to reproduce Taleyarkhan's work. Using similar acoustic parameters, deuterated acetone, similar bubble nucleation, and a much more sophisticated neutron detection device, the researchers could find no evidence of a fusion reaction. This work was reviewed by a team of four scientists, including an expert in sonoluminescence and an expert in neutron detection, who also concluded that no evidence of fusion could be observed.

Subsequent claims of replication

In 2004, new claims of bubble fusion were made by the Taleyarkhan group, claiming that the results of previous experiments have been replicated under more stringent experimental conditions. These results differed from the original results in that fusion was occurring for a much longer time frame than previously reported; the original report only showed neutron emission from the initial bubble collapse after the bubble nucleation whereas this report shows neutron emission many acoustic cycles later. The data however was lacking in that too large of a window was used for determination of a coincidence between the neutron emission and sonoluminescence light emission. Also, the energy of the detected neutrons was not consistent with neutrons produced from a fusion reaction. In July 2005, two of Taleyarkhan's students at Purdue University published evidence confirming the previous result. They used the same acoustic chamber, the same deuterated acetone fluid and a similar bubble nucleation system. In this report, no neutron-sonoluminescence coincidence was attempted; also the neutron energy was again not consistent with a neutron produced from a d-d fusion reaction

A report published in the journal Physical Review Letters claims further evidence of fusion. The initial news report, however, shows that the reaction does not always work correctly, and it is not known what parameters change to cause the reaction to function properly versus not function at all.

In November 2006, Edward R. "Ted" Forringer, Ph.D. and undergraduates David Robbins and Jonathan Martin of LeTourneau Universitypresented two papers at the American Nuclear Society Winter Meeting, claiming replication of neutron emission during a visit to the meta-stable fluids research lab at Purdue University. Their experimental setup was similar to the others, using a mixture of deuterated acetone,deuterated benzene, tetrachloroethylene and uranyl nitrate and, notably, operating without an external neutron source and using two types ofneutron detectors. They measured neutron levels at 8 standard deviations above the background level with a liquid scintillation detector, and 3.8 standard deviations above the background with plastic detectors. Measurements were within one standard deviation for the same experiment with a non-deuterated control liquid, demonstrating neutron production only during cavitation of the deuterated liquid.After this report, Purdue's investigation cleared Taleyarkhan of the charges, stating that they "determined that the evidence does not support the allegations of research misconduct and that no further investigation of the allegations is warranted."

Doubts prompt investigation

A claim as spectacular as the present one naturally arouses a lot of doubt. This culminated in a "special report" published in March 2006 byNature, that calls into question the validity of the results of the Purdue experiments. They quote Brian Naranjo of the University of California, Los Angeles with the claim that the measured spectrum is consistent with radioactive decay of the lab equipment and hence does not necessarily prove the presence of nuclear reactions. The response of Taleyarkhan et al. published in Physical Review Letters attempts to refute Naranjo's hypothesis as to the cause of the neutrons detected.

Doubts about the truthfulness of claims of positive observations have arisen within the Nuclear Engineering faculty of Purdue University. Because of these concerns, Purdue has initiated a review of the research, to be conducted by Purdue's Office of the Vice President for Research. In a March 9, 2006 article headed "Evidence for bubble fusion called into question", Nature reported that it had interviewed several of Taleyarkhan's colleagues who suspect something is amiss. On February 7, 2007, the Purdue University committee determined that "the evidence does not support the allegations of research misconduct and that no further investigation of the allegations is warranted", and that "vigorous, open debate of the scientific merits of this new technology is the most appropriate focus going forward."^]In order to verify that the investigation was properly conducted, House Representative Brad Miller requested full copies of its documents and reports by March 30,2007. A new review at Purdue has been initiated because the only papers supporting Taleyarkhan's work are those done at Taleyarkhan's lab.

Nature's suggestion of misuse of funds ill-founded?

In July 2006, Nature publicized a claim of Seth Putterman, denied by Taleyarkhan, to the effect that DARPA funds were used to support an experiment reported in Physical Review Letters without the source being acknowledged. This may seem a matter of minor importance. Dr. Brian Josephson raised questions as to Nature's motives by pointing out that, in the article, a conspicuous display of Putterman's arguments headed "where did the money go?" is immediately followed by a paragraph devoted to "misuse of federal dollars". Since Putterman does not himself consider funds were misused, it is unclear why such a paragraph should have been included if there were no intent at all to make the reader think this might have been the case.

Another problem with Nature's stance (the journal has stated "[we] believe that we have nothing to apologise for, and nothing to correct")^[unverified] is that the accounting details obtained by Putterman do not appear necessarily to support his conclusions. Despite the damaging effects that the publication of a flawed allegation is likely to have had, the journal is still at this time refusing to publish a clarification.

Ethical dimension

The ethical aspect of Nature's coverage of bubble fusion is complementary to that addressed in the above, and has equally been a cause of concern. Taking the Society of Professional Journalists' Code of Ethics as the norm, one may note the following in relation to the article concerned:

1. According to the code, journalists should "test the accuracy of information from all sources and exercise care to avoid inadvertent error". As noted above, the accounting details listed in the article do not appear to support Putterman's possibly damaging conclusions: however, they are presented in the article in a way that suggests that they do.

2. Journalists should also "make certain that headlines ... do not misrepresent. They should not oversimplify or highlight incidents out of context." Merely posing the question "Where did the money go?", which appears very conspicuously in the article, raises in the reader's mind the idea of fraud, a suggestion that the article itself does not in any way support.

New Energy Times writer Steven Krivit poses some questions about Nature's coverage in his piece "On Science, Journalism, and Nature".

INTRODUCTION TO SONOFUSION

Sonofusion is a developing alternate energy technology that has the potential to replace polluting hydrocarbons which include fossil fuels. The economics for sonofusion appear feasible now with its application to heating large structures. Control of the environment where people shop and work could use sonofusion for space heating where more than 30% of our available grid energy in the

is used. The future of sonofusion has the potential for the complete replacement of CO2 producing fuels. This would have world changing economic, political, and environmental consequences.

Sonofusion energy is harvested from many billions of TCBs, transient cavitation bubbles, produced/sec in 1 cc of D2O, the volume of the device that experimentally produces around 40 watts of sonofusion heat. There is a big advantage using small devices as large sonofusion devices at 20 and 40 KHz (thousand Hertz) that I initially used were expensive and inefficient by comparison. Also the number of bubbles produced per acoustic cycle per second is greatly increased at the higher frequencies. In all devices the TCBs are formed by ultrasound. The small device is driven by a 1.6 MHz (million Hertz) piezo with D2O circulating through its operating system. As the D2O passes through the device, it carries Qx produced by sonofusion and Qa from the acoustic ultrasound input and (if the oscillator is in the D2O flow its heat is also included). So all the heat input Qi plus Qx can be used for heating. The D2O circulation keeps the device from overheating.
To help with the monitoring of the device and its D2O environment the SL, sonoluminescence, photon emission was measured using a photomultiplier. SL is always associated with TCB production and has been studied throughout the world for years, but is still not understood. This puzzle has support from a varied spread of theories. The advantage of SL measurements provides direct knowledge of the device's TCB plasma condition as photons are emitted relate to the dissociation of D2O into deuterons, D+.
Power is generated from TCBs produced in D2O. D2O fuel is found in ordinary water to the extent of one part in 6000 and is potentially a million years of the world's energy supply. The amount of energy that can be extracted from D2O is 1 million times that of gasoline. The cost of very high grade D2O is 50 cents a gram and this one gram is more than enough to power a car for its lifetime (Einstein's mc2). The car will wear out before running out of its fifty grams of fuel. The reaction product of this fuel is helium with no long range radiation by-products as measured in the Los Alamos National Laboratory and my twenty years of experience working with this cavitation process. Like the puzzle of SL, the lack of radiation products in the sonofusion phenomenon is explained by several published theories and is still controversial.
The experimental apparatus, data collected and its graphical representation are presented on page 2 and needs more explanation. The sonofusion device is very small and at this point is the size of a wristwatch weighing 20 grams, producing 40 watts, and using 1 gm of D2O. These small devices can be ganged together to form a battery like device of any size with a high energy density. To avoid overheating it is important to remove the heat quickly.

1.6 MHz device sonofusion device (Series A)

Experimental

Data Plot

Watts Excess Qx	Watts in (wall) Qi	K counts/ sec PMT SL
14.5	29.0	2.7
18.3	29.4	4.2
16.4	29.4	4.4
28.6	43.4	7.5
34.3	50.4	10.5
38.2	50.4	10.5
7.5	17.0	1.1
4.0	9.4	0.7
1.3	4.2	0.1
0.6	2.0	0.0

Experiemental. The 1.6 MHz piezo oscillator device, orange, drives the sonofusion device as the D2O, blue, is circulated through it by the pump. The D2O is saturated with Ar in the bubbler. In the circulation line are the pump, heat-exchanger, filter, sonofusion device, flow-meter, and bubbler. The heat-exchanger's H2O, light-blue, removes heat from D2O maintaining a constant temperature to the sonofusion device. The PMT, photomultiplier device, measures the level of SL photons that indicate the condition of the plasma in the final stage of the TCB collapse. These experiments require complete darkness
Data Plot. Graph I shows the resultant, purple , of three parameters (Qx, Qi, and SL) measured during the initial experiments of Series A with the low mass 1.6 MHz sonofusion device. SL, sonoluminescence, indicates the presence of the high density partial plasma from the collapse of TCBs in D2O. The TCB collapse process produces jets during the last stage of the bubble collapse. These jets contain D+ and e- plasma that are accelerated into a metal target where sonofusion takes place producing Qx, excess heat. Qi is the 60 cycle input from the wall which is related to Qa, driving the 1.6 MHz acoustic power oscillator. The acoustic input to the sonofusion device Qa equals 0.33 of Qi.

Low Mass 1.6 MHz Sonofusion Reactor

ABSTRACT
We are using one of the most remarkable pulsing systems that nature offers for producing
transient high energy densities and I have been fortunate enough to be involved with it for over
20 years. Over time we have increased the frequency of our piezo cavitation drivers and are now
at 1.6 MHz and find that our results are the same. Even better, the Qx /(reactor gm), the energy
density, is drastically increased when compared to our 40 and 20 KHz piezo systems [1,2,3]. The
cost is decreased by at least an order of magnitude and the durability is greatly increased. All Q
values in this paper are dQ/dt Joules/sec. or watts. The systems differ in several ways because of
the 40 times increase in frequency. These 1.6 MHz systems produce more sonoluminescence,
SL, and more but smaller bubbles and an energy density in the collapsing bubble system that is
the same magnitude as the 40KHz systems [4,5]. In one cycle those small bubbles, initially a
few hundred nm in diameter, that are resonance size for the 1.6 MHz input will grow
isothermally. After the acoustic wave passes into its positive pressure phase the bubbles collapse
violently keeping a portion of their energy. In the final stage of collapse the energy densities are
literally astronomical. The collapse process produces from the bubble a jet that implants
deuterons into a target foil. The time frame for this 1.6 MHz system is 40 times faster than for
the 40 KHz system. The number of deuterons (protons) in the jet drops from 109 to 105 but the deuteron high density remains the same. The 1.6 MHz low mass, LM, device (weighing 20 gm) produces the same excess heat, Qx, as the 40 KHz system (weighing 3 Kgm). The calorimetry is a D2O or H2O flow-through system measuring its T in and T out with a DT value probably a little lower than the true value. The flow of D2O is measured at 60 ml/min. or 1 ml/sec. The total errors in the Qx measurements are in the order of 2 watts. These values range up to 40 watts depending on acoustic input, temperature, pressure, cavitating liquid and target.

INTRODUCTION

Over 15 years ago in 1989 I heard about the experimental work by Fleischmann and Pons at the University of Utah and within a few days I was using cavitating D2O with a Pd foil target. I saw evidence of foil melting and possible excess heat generation. Three years later after filing patents, the initial three individuals, Dick Raymond, Larry Klein, and myself invited Russ George and Steve Wolff with help from Tom Benson and together started EQuest Sciences. After a year

or so we produced helium four, tritium, and Qx. In 1998 EQuest was dissolved and transformed
into First Gate Energies with Dick Raymond still president. We were producing excess heat
using a 40 KHz system in amounts very similar to what we are producing today with our LM 1.6
MHz device.[1]

We moved our laboratory from Mountain View, CA to Kilauea, Kauai, HI in 2002. Most of our
efforts here have been directed to the LM 1.6 MHz sonofusion device. We have limited
resources so have lowered our goals to cutting costs and doing calorimetry experiments with the
measurement of Qx production. At this time we cannot afford to look for the products of Qx
production - the expensive analysis of helium and associated products. These products have been
found in the past [2,3] in our lower frequency reactors. The investigation was undertaken to
advance sonofusion technology and to find better and more compelling data showing Q

Bubble bursts for ‘sono-fusion’

Jul 24, 2002

A new study has cast further doubt on controversial claims made earlier this year that nuclear fusion was achieved in a bench-top ‘sonoluminescence’ experiment. In the first measurements of their kind, Yuri Didenko and Kenneth Suslick of the University of Illinois in the

tracked the processes that occurred in a single bubble in water when it was compressed by pulses of sound. They conclude that endothermic chemical reactions would make it “exceedingly difficult” to reach the high temperatures needed to spark nuclear fusion in such bubbles (Y Didenko and K Suslick 2002 Nature 418 394).

Bubble bath

Bubbles trapped in a liquid can be forced to expand and contract by firing acoustic pulses into the liquid. When a bubble expands, molecules from the surrounding liquid evaporate into it. This vapour is then compressed when the bubble contracts, and can reach temperatures and pressures that are high enough to kick-start chemical reactions and spark the emission of light – a phenomenon known as sonoluminescence.

In March, physicists in the

caused a stir when they claimed to have seen deuterium nuclei fuse in bubbles in ‘deuterated’ acetone. The team led by Rusi Taleyarkhan of Oak Ridge National Laboratory calculated that the temperature inside the bubbles must have reached tens of millions of degrees for the reaction to proceed. But many researchers working in the field dismissed these claims.

Now Didenko and Suslick have shed some light on the controversy by studying how the acoustic energy is distributed between chemical reactions, light emission and bubble collapse during sonoluminescence. To do this, they created a bubble – which was 30 µm across – in a water-filled cell, and made it oscillate using an acoustic signal with a frequency of 52 kHz.

To monitor the production of hydroxyl ions, nitrous oxide ions and photons in the bubble – which contained air and water vapour – the pair used fluorescence techniques and spectroscopy. Measurements were made at both 3 and 22 °C.

At its largest, the bubble had a potential energy of several MeV, and the researchers found that most of this energy is dissipated as shock waves and motion in the surrounding liquid. They also discovered that less than a millionth of this energy is converted into light, but about a thousandth of the energy is used to ionize the molecules of water vapour in the bubble.

According to Didenko and Suslick, this suggests that chemical reactions would soak up too much of the energy for nuclear fusion to take place, especially for bubbles in volatile liquids like acetone. The molecules of vapour in such bubbles are complex, and would absorb much more energy than the water vapour that they studied. But Suslick does concede that “the possibility of fusion occurring in low-volatility fluids – such as liquid metals and molten salts – cannot be ruled out at this time.”

There have been previous studies of the chemical reactions and light production associated with sonoluminescence, but these have focused on clouds of bubbles rather than single ones. These experiments have been difficult to interpret because it is hard to tell how many of the bubbles in the cloud are active at any one time.

THUS CONCLUDED AS
"Sonoluminescence arises from acoustic cavitation -- the formation, growth and implosion of small gas bubbles in a liquid blasted with sound waves above 18,000 cycles per second. The collapse of these bubbles generates intense local heating."

NOTE: The informations framed are from various internet resources.so there may be some errors and mistakes. mail me your views and queries .

Thanks for visiting

Bubble power

HVDC

High-voltage direct current

Introduction:

Contents

//<![CDATA[ if (window.showTocToggle) { var tocShowText = "show"; var tocHideText = "hide"; showTocToggle(); } //]]> High voltage transmission:

History of HVDC transmission

Advantages of HVDC over AC transmission

Disadvantages

Costs of high voltage DC transmission

Rectifying and inverting

Ø Components

Ø Rectifying and inverting systems

Ø Configurations

Ø Monopole and earth return

Bipolar

Back to back

Systems with transmission lines

Tripole: current-modulating control

Corona discharge

Applications

Ø Overview

Ø AC network interconnections

Ø Renewable electricity superhighways

Ø Smaller scale use

2. INTRODUCTION

3. AN IDEA OF SONOFUSION

6. FUSION REACTIONS TO PRODUCE ELECTRICITY

7. WHEN THE DREAM BECOMES REAL

8. CONCLUSION

INTRODUCTION

AN IDEA OF SONOFUSION

FORMATION OF BUBBLES

FUSION REACTIONS TO PRODUCE ELECTRICITY

WHEN THE DREAM BECOMES REAL!!!

CONCLUSION

Contents

Differences between deuterium and common hydrogen (protium)

Chemical symbol

Natural abundance

Physical properties

Quantum properties

Nuclear properties

Deuterium as an isospin singlet

Approximated wavefunction of the deuteron

Magnetic and electric multipoles

Deuterium radius

Applications

Deuterium in nuclear reactors

Deuterium NMR spectroscopy

A stable isotope tracer

Neutron scattering scattering contrast properties

Nuclear resonance spectroscopy

History

Lighter element isotopes suspected

Deuterium predicted and finally detected

"Heavy water" experiments in World War II

Name

Data

See also

BUBBLE POWER

sonoluminescence: Bubble power

How It Works: Bubble Power

Bubble power

sonofusion

Contents

Original experiments

Oak Ridge replication

Subsequent claims of replication

Doubts prompt investigation

Nature's suggestion of misuse of funds ill-founded?

Ethical dimension

INTRODUCTION TO SONOFUSION

1.6 MHz device sonofusion device (Series A)

THUS CONCLUDED AS

High voltage transmission: