LNG can be used as car fuel, as well as CNG (compressed natural gas) can. Both these fuels have significant advantages over gasoline and diesel fuel.

Because of the liquid state, LNG is more than twice as dense as CNG. It needs to be stored in insulated tanks because of the low temperature, but under pretty low pressures, as compared to compressed natural gas. The latter requires over 200 times atmospheric pressure (3,000-3,600 psi, or 21 to 25 MPa), while LNG requires only 70-150 psi (0,5-1,0 MPa, 5-10 times the atmospheric pressure). LNG is supplied to the engine in liquid state and then vaporised, similarly to LPG (liquefied petroleum gas, propane-butane mix, also known as autogas). 

Liquefied Natural Gas in car engines

LNG can be used in spark ignition (gasoline-powered) engines, that can be modified to run as dedicated for natural gas, or bi-fuel. In some cases it is possible to convert the engine to tri-fuel capacity (for CNG/LNG, LPG and gasoline), but this is mostly used in generator engines, and not in cars.

Compression ignition (diesel) engines can run on LNG as well, but only to a certain point. LNG cannot be ignited by compressing it in the engine, so a small dose of diesel fuel (pilot dose) must be maintained in order for the engine to work. On the other hand, the engine can be retrofitted with spark ignition system.

LNG vs gasoline, diesel and LPG

LNG seems to wear out the engine parts slower than gasoline does.

Emissions from natural gas are cleaner, as this fuel consists mainly of methane (CH4), very simple hydrocarbon, easy tu burn clean and efficiently. Natural gas engines produce much less particulate emissions, unburnt carbon (soot) and carbon monoxide.

LPG has different chemical composition (mainly propane C3H8 and butane C4H10), is much denser as a liquid and can be a liquid in room temperatures under pretty low pressures. Because of that it’s much easier to liquify autogas than natural gas (it requires much less energy). And this means it’s significantly cheaper. For example for the CNG the cost of compression is 20% of total fuel cost!

On the other hand, LPG is heavier than air (methane is lighter), and this causes it to collect in low spots, making it more hazardous to use.

Liquefied natural gas distribution

Natural gas is distributed under pressure via natural gas lines. In theory, filling stations for LNG cars could be located anywhere, as long as there is the natural gas supply. In practice, liquification plants require enormous investments and because of that are built on large scale.

Because of that it is assumed that LNG will be distributed using tankers, and not produced locally.

LNG conversion kits

It’s possible to get conversion kit to LNG for gasoline or diesel engines in many countries, and to get a vehicle converted by a qualified professional.

It doesn’t surprise that the best feedstock for ethanol production is the wheat, along with other grains, like corn and buckwheat. Raisins and prunes work great as they’re dried, and thus contain a lot of sugar per unit mass.

But I was surprised to learn that you can make more ethanol from onions or garlic, than from potatoes. If you have access to significant amounts of garlic or onion waste, you can produce a lot of alcohol fuel from it!

This table was taken from the book “Alcohol can be a gas!” by David Blume, the best alcohol fuel encyclopedia ever!I suggest getting one, though I don’t think that ethanol produced on a large scale can be considered a petroleum alternative.

Therefore, although it is safe to invest money in established alternate energy solutions, especially solar panels, because the government is spending billions to foster their development, one should be careful before spending money and thought on miraculous alternate energy solutions like ethanol. A common notion that has been slowly gaining ground is that biofuels like ethanol can offer a long term solution to America’s fuel crisis and provide substantial returns to investors. This notion, although technically true, yet has several real life obstacles facing it before it turns into a successful alternative to gasoline.

These pumps provide both E85 and E30 ethanol fuels. Photo: ethanolpics.

First, and most important of all, the ethanol produced from corn actually costs more to produce than gasoline. Although, the federal government is presently providing tax cuts to encourage ethanol production and supply, yet there is no guarantee that the tax cuts will be continued in the future. The upswing in the use of ethanol as fuel to be produced from corn has already generated significant impact on the corn farmlands, thereby pushing up the cost of cattle feed and also the price of other animal products.

Although the ethanol manufacturers are making huge profits and ethanol investment is hot on wall street, yet the truth is that ethanol is an extremely costly fuel and even with the tax cuts it actually costs more to produce one gallon of ethanol than one gallon of gasoline. Moreover, transportation and storage of ethanol is also a significant issue. It can not be transported by pipelines as it binds with water. Because of that, storage is also a problem.

Last, but not least — in most cases, EROEI of ethanol production is very close to unity. It means that if you invest some energy in production of ethanol, you will get only about as much energy in ethanol, as you invested.

I believe not. I think that it’s better to use straight or waste vegetable oil, and not biodiesel.

Biodiesel is a fuel manufactured from vegetable oils or animal fats and methanol. You might say that this fuel is fully renewable, as both vegetable oils and methanol can be produced from plants: oils from soya, canola (rapeseed) or sunflower (or a lot of different plants) while methanol is a product of wood pyrolysis. The necessity of using sodium or potassium hydroxide as catalyst doesn’t change much.

But in my opinion it is better to use vegetable oil directly in the diesel engine, instead of producing biodiesel. Its production requires some energy input so that the oil can be transesterified into biodiesel. This makes the EROEI a bit smaller.

Of course to use the vegetable oil in engine you need some changes to the engine itself. This fuel has noticeably higher viscosity so that it is not easily sprayed by injection nozzles. Because of that, vegetable oil needs to be heated before it can be supplied to the injection pump.

Vegetable oil use in winter is very difficult, but biodiesel also gels in cold temperatures. Both those fuels are not suitable for colder climates and colder seasons.

When it comes to producing biofuels, or any fuels in general (even the ones derived from the petroleum), you use a similar factor, called EROEI. It is an abbreviation of Energy Return On Energy Invested. For a specific fuel it shows how much energy you obtain from this fuel when compared to the energy used to producing it.

For example, for the first generation biofuels (derived from corn, vegetable oil, etc.), the formula is the following:

The EROEI of bioethanol equals the amount of energy stored in the fuel (heating value) derived by energy used for production: farming and harvesting of the feedstock (corn), sending it to the biofuel factory, and the biofuel production (drying, fermentation, distillation). To the energy used for farming the corn you need to add the energy used to produce fertilizers, that are mostly produced with use of natural gas (that could be burned elsewhere).

EROEI for bioethanol is close to unity, so it means that from burning the ethanol we get as much energy as we use to produce it. You can increase this factor by using less energy for production (for example to use renewable energy like solar power to distill the ethanol) or decrease it (e.g. when you haul the corn for long distances).

EROEI for fuels like biogas or biodiesel is noticeably greater. You need far less energy to produce those fuels. Biogas doesn’t need the energy-thirsty distillation but only cleaning and compressing. Biodiesel also does not need distilattion, only the transesterification (the scientific name for the most important part of biodiesel production), that requires much less energy.

EROEI smaller than 1?

One might think that it is not reasonable to produce any fuel with EROEI smaller than one. It means that you get less energy from the fuel than you used to produce it. Wouldn’t it be better if we used the energy directly instead of the fuel, and not waste it to produce that fuel?

In some cases it will surely happen. For example, when you use some low quality energy or fuel to produce better quality fuel. Like coal, that is not a good fuel for cars can be used to produce gasoline alternatives in a group of processes called CtL (Coal to Liquid, like Fischer-Tropsch process).

In power and fuel sector noone really cares about indicators like EROEI, because not the energy balance but the money is the most important factor.

To make the formula I used cliparts downloaded from www.clker.com.

There is no simple answer to that question. Those engines differ a lot in power/torque and efficiency/MPG, the fuels cost is also different. There are many additional questions you might ask to help you make a decision, e.g. do you want to spend more on the engine that will be more efficient and use cheaper fuel?

So let’s take a look at this question only from one point of view: the ability to use alternative fuels if standard fuels become very expensive or even unobtainable.

There are many different alternative car fuels, biodiesel, ethanol, methanol, compressed natural gas, hydrogen, liquefied petroleum gas (propane) and many more. Are those fuels suitable for both diesel and gasoline engines?

Well, many are suitable. For example, wood gas, CNG and LPG may be used in both diesel and spark ignition engines. If you don’t want to make serious adjustments to your engine, than the gasoline engine would be better, as the compression ignition engine needs some source of ignition — a small pilot dose of diesel fuel. If there’s no diesel, you won’t run your compression ignition on any alternative gaseous fuel without installing an entire ignition system: coil, spark plugs, controller, etc.

Think about all the alternative fuels you can make on your own, that is:

• vegetable oil / biodiesel,
• alcohol – ethanol,
• wood gas,
• biogas.

Only two of those fuels will work well in a standard diesel engine, the vegetable oil and biodiesel. The rest require some extra diesel (biodiesel) fuel for the pilot injection.

You should also take into account the amount of work and energy to produce your alternative fuel. The ethanol can be made of any sugar-containing biomass, from rotten fruits to garlic… The wood gas can be made of almost any hardwood, preferably dry one. Biogas can be produced from virtually any biomass, including human and animal waste. Yet the biodiesel can be made only from vegetable oils or animal fats, and it narrows your feedstock a lot.

So if you only think about producing your fuel in the uncertain future, choose spark ignition engine. You will be able to use a variety of alternative fuels, and not be limited to one.

Biogas production, also known as anaerobic digestion, is a process in which a biodigestible matter (biomass) is transformed by bacteria to biogas. It is done in reactors called biodigesters, which you feed with all the waste biomass (cut grass, waste water — especially blackwater, . The remaining digestate is very nutrient-rich and can be used as a fertilizer. Because of that, I believe that anaerobic digestion is a better way to utilize waste biomass than composting, as the latter only produces fertilizer. Anaerobic digestion produces both fertilizer and biogas.

I posted here two years ago a short video on how to make small amounts of biogas, but today I will show you much better ways to make this fuel.

Many people think that it is difficult to produce biogas, but they’re wrong. If it was difficult, than China wouldn’t have more than 5 milions (!!) working and effective, yet very simple biodigesters. In China biogas plants are very popular way to utilize human, animal and plant waste. And are very easy to build.

Underground biogas plant

The first biodigester design I wanted to show you, is the underground pit with three openings. One to feed the waste biomas, second to remove the digestate. The third is used to supply the biogas to your house. The produced biogas is stored inside the pit, in the large chamber, above the surface of biodigestible material, and supplied from there when needed.

Simple chinese biogas plant.

The image above was taken from a great book “A Chinese Biogas Manual” by Ariane van Buuren, published by Knowledge Publications as the third volume of the Biogas series. The book shows a bit of introduction to the idea of biogas production in China and describes in detail building of such simple biogas pit. Many different designs are shown, based on different materials available to use: stone slabs, hewn stone, brick or concrete.

For example, to build a biogas pit of 10 cubic meters  (353 cu.ft.) capacity you need:

• 1,250 – 1,500 kg (2,755-3,306 lbs) of lime,
• 200 kg (441 lbs) of cement,
• 2 cubic meters (71 cu.ft) of sand,
• 6 cubic meters (212 cu.ft) of large and small stones.

This book not only describes in detail how to build a simple biogas plant, but also how to utilize the produced fuel. You’ll find there a couple of burner designs (single tube burner, smoker’s pipe burner, spiral burner, long arm burner, showerhead burner, drum burner, revolving burner and several other designs), biogas stoves and even biogas lamps!

Of course the book contains a lot of important stuff about safety measures in both biogas production and use. You can buy it at Amazon.com for less than $20.

Drum-and-inner-tube-type

If you’d like to start with something easier to build in your backyard, you should consider another design, that utilizes one steel drum and one or more rubber inner tubes. The biodigestible matter is supplied to the drum and the biogas is stored in the inner tube(s). This design is not suitable for continuous use, after one batch of waste biomass is digested you have to empty the drum and fill it again with fresh feedstock.

Even simpler biogas plant, very easy to do it yourself from scratch.

This design is shown in full-detail in the second book I wanted to recommend, also published by Knowledge Publications, as the vols. 1&2 of Biogas series: “Biogas — what it is, how it is made, how to use it” and “Biogas 2 — building a better biogas unit”. Both books were prepared by FAO as a part of Better Farming Series and are fit inside one cover. If you ever read any book by FAO than you probably know how detailed those books are and how simply they’re written. No wonder, as they were written to be used all over the worlds, even in the smallest communities.

The design shown in the picture above was taken from the second book. As biogas is produced best in temperatures above the typical ambient temperature for Europe, Asia or North America, the book also describes good ways to insulate the biodigester. Two designs are shown, the better with drum and inner tube and the easier consisting of two drums of different size (one smaller put inside the second, larger). The simpler desing is a bit worse as some biogas is lost during operation.

The book can be purchased at Amazon.com for about $15.

Why produce biogas?

With one cubic meter (35 cu.ft.) of biogas you can:

• produce 1.25 kWh of electricity,
• substitute 0.7 kg of petrol,
• cook 3 meals for a family of 5-6,
• run 1 HP motor for 2 hours.

Is it really feasible not to use biogas, especially in off-grid locations? So when are you going to start making biogas?

Below you will find an exact copy of the Wiki’s article on anaerobic digestion. It’ll be used as a reference in my future articles.

~GetWIKI(Anaerobic_digestion)~

Or the opposite question: is it possible to pour heating oil into your diesel truck fuel tank?

Let’s find out…

Diesel fuel, or diesel oil, is a hydrocarbon fuel derived from petroleum / crude oil. Because of that, it is often called petrodiesel, to distinguish it from biodiesel, that is made of biomass. It consists of heavier hydrocarbons than petrol / gasoline, and is used to fuel diesel engines (compression ignition engines).

Heating oil is almost exactly the same as diesel oil. The chemical composition is almost entirely the same in both fuels. There may be only small differences:

• heating oil and diesel fuel are often taxed differently, to subsidise the use of heating oil in central heating,
• heating oil is often coloured (mixed with a dye) so that it can be easily distinguished from diesel fuel (and to make it easier to penalize the drivers who pour heating oil in their car fuel tanks),
• some heating oil and diesel fuel brands are said to have lower sulphur content — this lower sulphur content makes the fuel a bit more “dry” and reduces the lubricity.

In one sentence:

You can replace diesel fuel with heating oil and vice versa!

Replacing heating oil with diesel fuel is relatively easy. Your oil boiler or oil furnace doesn’t have any moving parts that need lubricant.

Using heating oil  as diesel fuel is a bit more risky, because of the possible lubricity difference. Using it for long time may reduce your engine lifespan.

The contents of the article below are automatically updated, so you can say it’s up to date.

~GetWIKI(Diesel_fuel)~