Constellation Energy Group will proceed with plans to sell a stake in its nuclear power business to Electricite de France SA, accepting conditions put on the merger by Maryland regulators.

The Maryland Public Service Commission last week approved Constellation’s $4.5 billion sale, which will give EDF just under 50 percent ownership of its nuclear power business, with conditions that require Constellation to give its customers a total of $110 million in rebates by next March. It also includes financial conditions that require Constellation to infuse its Baltimore Gas & Electric utility with $250 million.

The industry estimates that the basin has 100-150 more years’ worth of production, based on today’s technology. Though most mines are much smaller, there are more than 1,000 of them in the US. The government estimates there are several hundred years’ worth of coal to be recovered in the US - the Saudi Arabia of coal, with 27 per cent of the world’s known coal reserves. It would take a massive effort to replace coal production. Peabody Energy, which owns North Antelope and is the world’s largest private sector coal company, says replacing coal would be a gargantuan task. It would require 2,400 times more solar generation,40 times more wind power, 250 new nuclear plants, almost double the US production of natural gas, 500 hydro plants the size of the Hoover Dam or halving electricity consumption. Even then, the US would have to find a way to meet new demand, given growth forecasts.

Victor Der, principal deputy assistant secretary for fossil energy in the Obama administration, says: “It would be very difficult to move away from it. We believe coal will continue to be in the energy mix.”

Yet coal-fired electricity is responsible for enormous carbon dioxide emissions. Coal is the most carbon- intensive of all fossil fuels and the most widely used to generate electricity in the US. Generating electricity is the country’s largest source of CO 2 emissions - 41 per cent of the total.

As the Senate prepares to tackle global warming, the nation’s energy producers, once united, are battling one another over policy decisions worth hundreds of billions of dollars in coming decades.

Producers of natural gas are battling their erstwhile allies, the oil companies. Electrical utilities are fighting among themselves over the use of coal versus wind power or other renewable energy. Coal companies are battling natural gas firms over which should be used to produce electricity. And the renewable power industry is elbowing for advantage against all of them.

Some supporters of global warming legislation believe that the division in the once-monolithic oil and gas industry, as well as other splits among energy producers, could improve the prospects for the legislation.

Renewable energy threatens the planet. Who knew?

“Our nation runs the risk of damaging the environment, in the name of saving the environment.

“There are negative consequences from producing energy from the sun, the wind and the earth.”

So, at least, said Lamar Alexander, the Republican senator from Tennessee and a long-time conservationist, during a speech Monday at Resources for the Future.

A proposed federal rule is aimed at limiting carbon dioxide and other greenhouse gas emissions from the biggest U.S. sources, federal regulators said Wednesday.

Lisa P. Jackson, administrator of the Environmental Protection Agency, said the regulations would apply to power plants and other industrial facilities that emit at least 25,000 tons of greenhouse gases a year, The New York Times reported. She said most of the 14,000 facilities that would be covered are already required to get permits because of other emissions regulated by the Clean Air Act.

The 25,000-ton threshold is far higher than that applying to sulfur dioxide and other pollutants with more immediate health effects. The high threshold protects small businesses and other emitters like apartment buildings.

Government bodies and utility providers are in the early stages of this multibillion-dollar upgrade to transform the existing grid into a two-way network where power and information flow in both directions between the utility and the customer, not just from the provider to the user.

Done right, the revamp will cut bills, reduce consumption, give users more say in the kinds of energy they use, and even let customers produce their own energy and sell it back to power providers.

Here is an inconvenient truth about renewable energy: It can sometimes demand a huge amount of water. Many of the proposed solutions to the nation’s energy problems, from certain types of solar farms to biofuel refineries to cleaner coal plants, could consume billions of gallons of water every year.

“When push comes to shove, water could become the real throttle on renewable energy,” said Michael E. Webber, an assistant professor at the University of Texas in Austin who studies the relationship between energy and water.

Conflicts over water could shape the future of many energy technologies. The most water-efficient renewable technologies are not necessarily the most economical, but water shortages could give them a competitive edge.

Two of the nation’s largest power generators said Thursday that they plan to begin switching their company cars and trucks to plug-in hybrid vehicles or all-electric vehicles starting Jan. 1 to help cut greenhouse gas emissions.

The commitment by Charlotte, N.C.-based Duke Energy and Juno Beach, Fla.-based FPL Group Inc. represents more than 10,000 vehicles and potential revenue of $600 million or more for manufacturers.

The goal is that by 2020, 100 percent of all new fleet vehicles will be plug-in electric vehicles or plug-in hybrid vehicles.

A two-judge panel of a federal appeals court has ruled that big power companies can be sued by states and land trusts for emitting carbon dioxide. The decision, issued Monday, overturns a 2005 District Court decision that the question was political, not judicial.

A panel of the United States Court of Appeals for the Second Circuit, in New York, ruled that eight states — California, Connecticut, Iowa, New Jersey, New York, Rhode Island, Vermont and Wisconsin — as well as New York City and three land trusts could proceed with a suit against American Electric Power, Southern Corporation, the Tennessee Valley Authority, Xcel Energy and Cinergy Corporation, all large coal-burning utilities.