Decades ago the only type of car was the internal combustion (gasoline)type. Other varieties have arrived such as Hybrid and electric. With the new choices are other decisions such as which one reduces most the carbon footprint (or is the most green)and which one is the most cost effective. No more is "the miles per gallon" a standard that can be applied across the board as a specification.

In the effort to slow the pace of global warming, researchers and policy makers are encouraging the use of lighter colors for rooftops and streets worldwide. Dark, non-reflective surfaces which are common for asphalt and asphalt shingles, absorb heat from the sun and create a "heat-island" effect, plus a greater need for air conditioning. Lighter surfaces would reflect the sun’s rays back to outer space, reducing ground-surface temperatures and overall energy requirements.

The United States and dozens of other countries have pledged hundreds of millions of dollars toward clean energy initiatives to help battle climate change, U.S. Energy Secretary Stephen Chu said on Tuesday. Meeting in Washington, D.C., for a two-day conference, delegations from 24 countries representing 80 percent of global energy consumption promised 11 initiatives that would mean building fewer power plants and using more clean energy. "We know the clean energy challenge won't wait, and we won't wait either," Chu said. With the U.S. Senate virtually gridlocked on passing an energy and climate change package this year, the Obama administration is under pressure to provide leadership in global climate talks that are making little progress.

Engineers monitoring BP Plc's damaged well in the Gulf of Mexico detected seepage on the ocean floor that could mean problems with the cap that has stopped oil from gushing into the water, the government's top oil spill official said on Sunday. Earlier on Sunday, BP officials had expressed hope that the test of the cap which began Thursday could continue until a relief well can permanently seal the leak next month. Oil gushed from the deep-sea Macondo well for nearly three months until the new cap was put in place last week. But late on Sunday, the U.S. government released a letter to BP Chief Managing Director Bob Dudley from retired Coast Guard Admiral Thad Allen that referred to an unspecified type of seepage near the mile-deep (1.6 km-deep) well along with "undetermined anomalies at the well head." "I direct you to provide me a written procedure for opening the choke valve as quickly as possible without damaging the well should hydrocarbon seepage near the well head be confirmed," Allen wrote.

BP Plc extended for another 24 hours a critical test of its blown-out Gulf of Mexico well that so far has shut off the huge oil leak, the top U.S. official overseeing the spill response said on Saturday. The British energy giant, which cut off the flow of oil from the deep-sea well on Thursday when it began the test to gauge its structural integrity, expressed growing confidence that the well was intact. Kent Wells, BP's senior vice president of exploration and production, said there was no evidence of any leaks. "We're feeling more comfortable that we have integrity" in the well, Wells added, in what would be an important step toward permanently plugging it.

Washington, D.C.- Improved drilling techniques have unlocked vast new reserves of shale gas, a resource that could be large enough to displace significant amounts of coal, and an energy source that emits less than half the carbon dioxide. But growing shale gas development has raised both environmental questions and public controversy. A new independent assessment by the Worldwatch Institute concludes that improved adherence to drilling best practice and better regulatory oversight are essential to assure environmental and public protection as shale gas production continues to expand.

WASHINGTON, DC — - Today, the Environmental Protection Agency (EPA) announced it would require the domestic use of 800 million gallons of biodiesel in 2011. This is consistent with the renewable goals established in the Energy Independence and Security Act of 2007 (EISA), which expanded the Renewable Fuels Standard (RFS2) and specifically requires a renewable component in U.S. diesel fuel.

Oil is no longer spewing into the Gulf of Mexico -- at least temporarily -- as BP Plc said it choked off the flow from its undersea well that ruptured in April and caused the worst offshore oil spill in U.S. history. BP said it stopped the leak on Thursday with the tight-sealing containment cap installed three days earlier atop its blown-out well, and awaited on Friday the results of tests on whether the well remains intact. That's a key issue as the British energy giant moves to plug the leak permanently with a relief well intended to intersect the ruptured well -- which extends 2.5 miles under the seabed -- and seal it with mud and cement next month.

Energy-efficient homes have significantly lower default and delinquency rates than typical homes, according to an internal analysis conducted for a major financial institution last year. Here's yet another reason why it makes no sense that Fannie Mae and Freddie Mac have effectively killed Property Assessed Clean Energy (PACE), a financing tool that has helped make efficiency improvements affordable for thousands of American homeowners.

Two U.S. business groups opposed on Wednesday the latest version of a climate change proposal circulating in the U.S. Senate, saying it was unfair to power companies and would hurt energy-intensive industries. Senators John Kerry, a Democrat, and Joe Lieberman, an independent, have crafted a draft bill focusing on capping greenhouse gas pollution from electric power utilities first. It scales back previous ambitions for a broad attack on emissions. The plan would launch a "cap-and-trade" market in which utilities that cut pollution could sell credits to companies that do not. It expects overall emissions limits would be achieved because the cap on all utilities toughens over time.

BP finished pumping cement into its ruptured oil well in the Gulf of Mexico on Thursday to seal off the source of the world's worst offshore spill, paving the way to permanently plug the blow-out later this month. The daylong cementing operation followed earlier injections of heavy drilling mud this week that had subdued the upward pressure of oil and gas inside the deep-sea Macondo well. The crippled wellhead was provisionally capped in mid-July. "This is not the end, but it will virtually assure us that no oil will be leaking into the environment," retired Coast Guard Admiral Thad Allen, who oversees the U.S. oil spill response operation, said at a briefing in Washington. "Monitoring of the well is under way in order to confirm the effectiveness of the procedure," BP said in a statement announcing completion of the cementing work.

Small units that purify household sewage could provide a source of electricity for urban and remote communities in the developing world, according to researchers. The units would be populated with Shewanella oneidensis, one of several types of bacteria that can break down organic matter in sewage, producing electrons and protons. If the sewage is placed between electrodes with the bacteria present, this process can be harnessed to generate an electrical current.

BP Plc on Tuesday delayed a critical test that will determine if it can close a cap atop its ruptured Macondo well that has leaked oil into the Gulf of Mexico for the last 12 weeks. The British energy giant and U.S. authorities said they were postponing the test that had been scheduled for Tuesday to establish whether the well can withstand the pressure caused by closing the cap at the wellhead. "We decided that the process may benefit from additional analysis that will be performed tonight and tomorrow," retired Coast Guard Admiral Thad Allen, who is overseeing the U.S. response to the spill, said in a statement. The tests, due to last between six and 48 hours, had been scheduled for late Tuesday on BP's newly installed "capping stack," which has a better seal than the last cap placed on the well and aims to stop oil from spewing out of the failed blowout preventer.

BP prepared on Tuesday to try sealing off its runaway well with a new cap that it says could for the first time in 12 weeks finally arrest the flow of oil spewing from the floor of the Gulf of Mexico. The British energy giant has suffered numerous setbacks in its struggle to control the 85-day-old gusher that stands as the worst offshore oil spill in U.S. history. And BP cautioned that tests of its latest containment system were not sure to succeed.

Renewable energy is energy which comes from natural resources such as sunlight, wind, rain, tides, and geothermal heat, which are renewable as opposed to fossil fuels for example which once gone are gone. In 2008, about 19% of global final energy consumption came from renewables, with 13% coming from traditional biomass, which is mainly used for heating, and 3.2% from hydroelectricity. The EPA has just named the 50 green power partners (individual purchasing sources or companies) using the most renewable electricity. The Green Power Partnership’s top purchasers use more than 12 billion kilowatt-hours (kWh) of green power annually, equivalent to the annual carbon dioxide (CO2) emissions from the electricity use of more than 1 million average American homes. Green Power users pollute less and do not use up non-renewable sources.

BP Plc said on Friday it could seal its ruptured Gulf of Mexico oil well by next week as the House of Representatives voted to toughen regulation of offshore energy drilling. Incoming BP Chief Executive Bob Dudley said the British energy giant would attempt a "static kill" operation on Tuesday to try to plug the blown-out deep-sea well that caused the worst offshore oil spill in U.S. history. This marks a slight delay. The U.S. official overseeing the spill response, retired Coast Guard Admiral Thad Allen, had said on Thursday he hoped the operation to pump mud and cement into the well could be performed as early as this weekend. As BP moved ahead with its plans, U.S. government scientists said South Florida, the Florida Keys and the U.S. East Coast likely will be spared from oil pollution from the spill despite earlier dire warnings.

Solar power is the generation of electricity from sunlight. This can be direct as with photovoltaics, or indirect as with concentrating the sun's rays to boil water which is then used to provide power. Solar energy can be obtained in a variety of different ways. Passive solar occurs when you build your house in a manner that takes advantage of the low angle winter sun and/or when the mass of your house is used to absorb the sun’s heat in winter. In addition, passive solar also refers to keeping your house cooler in the winter months by making adjustments that include placing trees and awnings along the south side of a house.

BP Plc removed a containment cap from its stricken Gulf of Mexico oil well on Saturday in the first step toward installing a bigger cap to contain all the crude gushing into the sea and fouling the coast. The maneuver released a torrent of oil that will spew unrestrained into the Gulf for four to seven days -- the time BP says it will take to put in place a bigger cap and seal. Officials say the new cap would capture all the oil leaking from the well and funnel it 1 mile upward to vessels on the water's surface. The new solution, 82 days into the worst oil spill in U.S. history, would not allow crude to billow out the bottom and the top, as the current cap does, said Kent Wells, senior vice president of exploration and production for BP. "The difference is one completely seals and the other didn't," Wells said.

A giant glider-like aircraft has completed the first night flight propelled only by solar energy, organizers said on Thursday. Solar Impulse, whose wingspan is the same as an Airbus A340, flew 26 hours and 9 minutes, powered only by solar energy stored during the day. It was also the longest and highest flight in the history of solar aviation, organizers said. Bertrand Piccard, the Swiss president of the project, best known for completing the first round-the-world flight in a hot air balloon in 1999, said the success of the flight showed the potential of renewable energies and clean technology. "We are on the verge of the perpetual flight," he said.

Upper atmospheric lightning or upper atmospheric discharge are terms sometimes used by researchers to refer to a family of electrical breakdown phenomena that occur well above the altitudes of normal lightning. The preferred current usage is transient luminous events (TLEs) to refer to the various types of electrical discharge phenomena in the upper atmosphere, because they lack several characteristics of the more familiar lower atmospheric lightning. TLEs include red sprites, sprite halos, blue jets, gigantic jets, and elves.