Anti-wind groups are attempting to defy the laws of physics with their claims.

by Michael Goggin, American Wind Energy Association

Washington, DC, United States – Recent data and analyses have made it clear that the emissions savings from adding wind energy to the grid are even larger than had been commonly thought. In addition to each kilowatt-hour (kWh) of wind energy directly offsetting a kWh that would have been produced by a fossil-fired power plant, new analyses show that wind plants further reduce emissions by forcing the most polluting and inflexible power plants offline and causing them to be replaced by more efficient and flexible types of generation.

At the same time, and in spite of the overwhelming evidence to the contrary, the fossil fuel industry has launched an increasingly desperate misinformation campaign to convince the American public that wind energy does not actually reduce carbon dioxide emissions. As a result, we feel compelled to set the record straight on the matter, once and for all.

Fossil Fuel’s Desperate War against Facts

Not to be deterred by indisputable data, numerous refutations, or the laws of physics, the fossil fuel lobby has doubled down on their desperate effort to muddy the waters about one of the universally recognized and uncontestable benefits of wind energy: that it reduces the use of fossil fuels as well as the emissions and other environmental damage associated with producing and using these fuels.

For those who have not been following this misinformation campaign by the fossil fuel industry, here is a brief synopsis. Back in March 2010, AWEA heard public reports that the Independent Petroleum Association of Mountain States (IPAMS), a lobby group representing the oil and natural gas industry, was working on a report that would attempt to claim that adding wind energy to the grid had somehow increased power plant emissions in Colorado.

Perplexed at how anyone would attempt to make that claim, AWEA decided to take a look at the relevant data, namely the U.S. Department of Energy’s data tracking emissions from Colorado’s power plants over time. The government’s data, reproduced in the table below, show that as wind energy jumped from providing 2.5% of Colorado’s electricity in 2007 to 6.1% of the state’s electricity in 2008, carbon dioxide emissions fell by 4.4%, nitrogen oxide and sulfur dioxide emissions fell by 6%, coal use fell by 3% (571,000 tons), and electric-sector natural gas use fell by 14%. (Thorough DOE citations for each data point are listed here (PDF).) Two conclusions were apparent from looking at this data: 1. the claim the fossil fuel industry was planning to make had no basis in fact, and 2. the fossil industry was understandably frustrated that they were losing market share to wind energy.

Change in Colorado Power Plant Fossil Fuel Use and Emissions from 2007-2008, as Wind Jumped from Providing 2.5% to 6.1% of Colorado Electricity

In early April, AWEA publicly presented this government data, and when the fossil fuel lobbyists released their report later that month it was greeted with the skepticism it deserved and largely ignored. Case closed, right? We thought so, too.

After the initial release of the report fell flat, the fossil fuel industry tried again a month later. John Andrews, founder of the Independence Institute, a group that has received hundreds of thousands of dollars in funding from the fossil fuel industry, penned an opinion article in the Denver Post parroting the claims of the original report. Fortunately, Frank Prager, a vice president with Xcel Energy, the owner of the Colorado power plants in question, responded with an article entitled “Setting the record straight on wind energy” that pointed out the flaws in the fossil industry’s study and reconfirmed that wind in fact has significantly reduced fossil fuel use and emissions on their power system. Having been shot down twice, we thought that the fossil industry would surely put their report out to pasture.

Yet just a month later the report resurfaced, this time in Congressional testimony by the Institute for Energy Research, a DC-based group that receives a large amount of funding from many of the same fossil fuel companies that fund the Independence Institute. The group has continued trumpeting the report’s myths at public events around the country and on their website, and these myths are now beginning to spread through the pro-fossil fuel blogosphere. In recent days, these myths have re-appeared in columns by Robert Bryce, a senior fellow at the fossil-funded Manhattan Institute.

The fossil fuel industry’s desperate persistence and deep pockets make for a dangerous combination when it comes to distorting reality, so we’d like to once and for all clarify the facts about how wind energy reduces fossil fuel use and emissions.

The Truth about Wind and Emissions

The electricity produced by a wind plant must be matched by an equivalent decrease in electricity production at another power plant, as the laws of physics dictate that utility system operators must balance the total supply of electricity with the total demand for electricity at all times. Adding wind energy to the grid typically displaces output from the power plant with the highest marginal operating cost that is online at that time, which is almost always a fossil-fired plant because of their high fuel costs. Wind energy is also occasionally used to reduce the output of hydroelectric dams, which can store water to be used later to replace more expensive fossil fuel generation.

Let’s call this direct reduction in fossil fuel use and emissions Factor A. Factor A is by far the largest impact of adding wind energy to the power system, and the emissions reductions associated with Factor A are indisputable because they are dictated by the laws of physics.

In some instances, there may also be two other factors at play: a smaller one that can slightly increase emissions (let’s call it Factor B), and a counteracting much larger one that, when netted with B, will further add to the emissions reductions achieved under Factor A (let’s call this third one Factor C).

Factor B was discussed at length in an AWEA fact sheet (PDF) published several years ago. This factor accounts for the fact that, in some instances, reducing the output of a fossil-powered plant to respond to the addition of wind energy to the grid can cause a very small reduction in the efficiency of that fossil-fueled power plant. It is important to note that this reduction in efficiency is on a per-unit-of-output basis, so because total output from the fossil plant has decreased the net effect is to decrease emissions.

As a conservative hypothetical example, adding 100 MW of wind energy output to the grid might cause a fossil plant to go from producing 500 MW at 1000 pounds of CO2 per megawatt-hour (MWh) (250 tons of CO2 per hour) to producing 400 MW at 1010 pounds of CO2/MWh (202 tons of CO2 per hour), so the net impact on emissions from adding 100 MW of wind would be CO2 emissions reductions of 48 tons per hour. Unfortunately, fossil-funded groups have focused nearly all of their attention on Factor B, which in this example accounts for 2 tons, while completely ignoring the 50 tons of initial emissions reductions associated with Factor A. (See Footnote 1.) A conservative estimate is that the impact of Factor B is at most a few percent of the emissions reductions achieved through factor A.

Factor C is rarely included in discussions of wind’s impact on the power system and emissions, but the impact of Factor C is far larger than that of Factor B, so that it completely negates any emissions increase associated with Factor B. Factor C is the decrease in emissions that occurs as utilities and grid operators respond to the addition of wind energy by decreasing their reliance on inflexible coal power plants and instead increase their use of more flexible – and less polluting – natural gas power plants. This occurs because coal plants are poorly suited for accommodating the incremental increase in overall power system variability associated with adding wind energy to the grid, while natural gas plants tend to be far more flexible. (Footnote 2)

To summarize, the net effect of Factors A, B, and C is to reduce emissions by even more than is directly offset from wind generation displacing fossil generation (Factor A).

Study after Study

Unsurprisingly, government studies and grid operator data show that this is exactly what has happened to the power system as wind energy has been added. A study by the National Renewable Energy Laboratory (NREL) released in January 2010 found drastic reductions in both fossil fuel use and carbon dioxide emissions as wind energy is added to the grid. The Eastern Wind Integration and Transmission Study (EWITS) used in-depth power system modeling to examine the impacts of integrating 20% or 30% wind power into the Eastern U.S. power grid.

The EWITS study found that carbon dioxide emissions would decrease by more than 25% in the 20% wind energy scenario and 37% in the 30% wind energy scenario, compared to a scenario in which our current generation mix was used to meet increasing electricity demand. The study also found that wind energy will drastically reduce coal generation, which declined by around 23% from the business-as-usual case to the 20% wind cases, and by 35% in the 30% wind case. These results were corroborated by the DOE’s 2008 technical report, “20% Wind Energy by 2030,” which also found that obtaining 20% of the nation’s electricity from wind energy would reduce carbon dioxide emissions by 25%.

The fact that this study found emissions savings to be even larger than the amount directly offset by adding wind energy is a powerful testament to the role of Factor C in producing bonus emissions savings. By running scenarios in which wind energy’s variability and uncertainty were removed, NREL’s EWITS study was able to determine that it was in fact these attributes of wind energy that were causing coal plants to be replaced by more flexible natural gas plants. (See page 174 of the study.)

As further evidence, four of the seven major independent grid operators in the U.S. have studied the emissions impact of adding wind energy to their power grids, and all four have found that adding wind energy drastically reduces emissions of carbon dioxide and other harmful pollutants. While the emissions savings depend somewhat on the existing share of coal-fired versus gas-fired generation in the region, as one would expect, it is impossible to dispute the findings of these four independent grid operators that adding wind energy to their grids has significantly reduced emissions. The results of these studies are summarized below.

Independent Grid Operators’ Calculations of Wind’s Emissions Savings

It is even more difficult to argue with empirical Department of Energy data showing that emissions have decreased in lockstep as various states have added wind energy to their grids. In addition and in almost perfect parallel to the Colorado data presented earlier, DOE data for the state of Texas show the same lockstep decrease when wind was added to its grid. This directly contradicts the Independent Petroleum Association of Mountain States report when it attempts to claim that wind has not in fact decreased emissions in Texas.

Specifically, DOE data show that wind and other renewables’ share of Texas’s electric mix increased from 1.3% in 2005 to 4.4% in 2008, an increase in share of 3.1 percentage points. During that period, electric sector carbon dioxide emissions declined by 3.3%, even though electricity use actually increased by 2% during that time. Because of wind energy, the state of Texas was able to turn what would have been a carbon emissions increase into a decrease of 8,690,000 metric tons per year, equal to the emissions savings of taking around 1.5 million cars off the road.

A Time for Change

The fossil fuel industry’s latest misinformation campaign is reminiscent of scenes that played out in Washington in previous decades, as tobacco company lobbyists and their paid “experts” stubbornly stood before Congress and insisted that there was no causal link between tobacco use and cancer, despite reams of government data and peer-reviewed studies to the contrary. It’s time we enacted the strong policies we need to put our country’s tremendous wind energy resources to use, creating jobs, protecting our environment, savings consumers money, and improving our energy security, even if it means leaving a few fossil fuel lobbyists behind.

Michael Goggin is electrical industry analyst at AWEA.

Footnotes:

1 Mr. Bryce’s recent Wall Street Journal article is the most creative in its effort to exaggerate Factor B and downplay factor A. In his article, Bryce exclaims about the “94,000 more pounds of carbon dioxide” that the IPAMS study claimed were emitted in Colorado due to Factor B. To be clear, 94,000 pounds is equivalent to the far less impressive-sounding 47 tons of carbon dioxide, or the amount emitted annually on average by two U.S. citizens. Yet just a few paragraphs later, Mr. Bryce speaks dismissively when noting a DOE report that found that, on net, wind energy would “only” reduce carbon dioxide by 306 million tons (enough to offset the emissions of about 15 million U.S. citizens).

2 It is important to keep in mind that the supply of and demand for electricity on the power system have always been highly variable and uncertain, and that adding wind energy only marginally adds to that variability and uncertainty. Electric demand already varies greatly according to the weather and major fluctuations in power use at factories, while electricity supply can drop by 1000 MW or more in a fraction of a second when a large coal or nuclear plant experiences a “forced outage” and goes offline unexpectedly, as they all do from time to time. In contrast, wind output changes slowly and often predictably.

[Editor's note: Footnotes 3-11 are embedded as links into the text above.]

Chart Footnotes:

12 Texas ERCOT Study (PDF)

13 Transmission Expansion Plan, Vision Exploratory Study, Midwest ISO (2006)

14 Mid-Atlantic Study (PDF)

15 New England Study (PDF)

This article first appeared in the August 2010 issue of Windletter and was republished with permission from the American Wind Energy Association (AWEA).

By Scott Rothschild of The Lawrence Journal-World

TOPEKA — A measure tucked into the state budget could prevent Kansas from implementing Environmental Protection Agency rules on greenhouse gases.

The proposal was shepherded through by Sen. Tim Huelskamp, R-Fowler, during the final days of the legislative session that ended last week.

“Instead of supporting sound science and common sense, the EPA has chosen to take the radical path of attempting to regulate carbon dioxide and methane,” said Huelskamp, who also is running for the 1st District congressional seat, currently occupied by Jerry Moran.

“I’m determined to do what is best for our Kansas economy, and that is to oppose the EPA implementation of their cap-and-trade regulatory scheme at every possible opportunity,” he said.

The amendment to the appropriations bill would prohibit any state agency from spending state funds “to plan, draft, propose, promulgate, finalize or implement any rules and regulations pursuant to the Clean Air Act involving the greenhouse gases identified” in the EPA’s endangerment finding.

EPA has declared that climate-changing greenhouse gases endanger human health and welfare and need to be regulated. Those gases include carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride.

The Kansas Department of Health and Environment, which enforces environmental rules, is the target of the amendment, and a major issue before KDHE is a pending permit for an 895-megawatt coal-fired electric power plant in southwest Kansas, known as the Sunflower Electric Power Project.

In 2007, KDHE Secretary Roderick Bremby denied the permit for the project, citing the effects of the proposal’s potential carbon dioxide emissions on health and environment.

In 2008 and 2009, Sunflower Electric and Colorado-based Tri-State Generation and Transmission Association, which would own most of the power from the project, pushed through legislation to overturn Bremby’s decision. Then-Gov. Kathleen Sebelius vetoed that legislation several times.

When Mark Parkinson became governor in 2009, after Sebelius’ departure to join President Barack Obama’s Cabinet, Parkinson made a deal with Sunflower and Tri-State to build a smaller project.

The amendment to the budget bill is now in the hands of Parkinson, who can let it become law or apply a line-item veto to it. Parkinson’s office said the governor has not yet received the appropriations bill but that once he does he will thoroughly consider every proviso before taking any action.

Environmentalists are unhappy with the amendment but, ironically, they are not asking for Parkinson to veto it.

Given Parkinson’s deal-making with Sunflower on the coal plant, they don’t see much help coming from the Statehouse.

“At this point, we’re not inclined to use the legislative process to combat these special interests anymore,” said Stephanie Cole, a spokeswoman for the Kansas chapter of the Sierra Club. “The legislative process is being abused. We will focus on the Sunflower project in the courts.”

Scott Allegrucci, director of the Great Plains Alliance for Clean Energy, said the provision wouldn’t stand up in court and probably would invite more scrutiny from the EPA on Kansas environmental regulation.

“We might consider more direct oversight by EPA a much more responsible and dependable pathway to regulatory certainty in Kansas,” Allegrucci said.

EPA’s Regional Administrator Karl Brooks has already written a letter to Parkinson and Bremby expressing concerns about any provision that would block federal rules.

In that letter, Brooks warns that if a state doesn’t follow federal pollution laws, the EPA will exercise its authority to make sure that projects seeking permits adhere to federal requirements.

By Steve Hargreaves of CNNMoney.com

The world seems awash in natural gas.

In the United States, new production from once hard-to-tap shale rock is booming in places like Texas, Louisiana and the Northeast. There are also plans to construct a mammoth gas pipeline through Canada to bring Alaskan North Slope gas to market.

In Australia and Qatar, liquefied natural gas terminals have started supplying fast-growing Asian countries, and more are under construction.

In Africa, rich natural gas deposits off the coast of Angola are slated for both the domestic market and export to Europe, which still gets a big part of its supply from Russia’s huge reserves. Plans are also underway to supply both Europe and Asia with the sizable gas reserves in Iran and Iraq.

Forecasting agencies, long known to play it safe before touting new trends, are only predicting a modest increase in gas’ share of the world’s overall energy mix by 2030.

But some analysts are saying it could be much higher, with big implications for the electricity markets – and coal-fired power plants in particular.

How much do we have?

In the United States, it’s this shale natural gas that’s got everyone so excited.

This gas has been known about for some time, but new drilling and extraction technology has now made it commercially viable. There are some concerns over the environmental impact of this drilling, especially water pollution, but the sheer amount of new gas is getting major attention.

“We’ve basically won the lottery,” Michael Ming, president of Research Partnership to Secure Energy for America, an organization that studies new natural gas developments, said during a recent Time Inc. conference on energy technologies.

The amount of gas reserves in these new shales could double the nation’s known stockpile of natural gas, according to U.S. Geological Survey estimates.

Yet the U.S. Energy Information Administration is only forecasting a rise in natural gas production of under 20% by 2030. And as our overall energy use is expected to rise as well, natural gas’ share of our overall energy mix will be little changed. EIA’s estimates are in-line with other private forecasts.

Ming is among those who believe estimates for natural gas use are too small. He pointed to estimates from 10 years ago that said just 1 trillion cubic feet of natural gas was likely in Texas’ Barnett Shale. That estimate is now 50 trillion cubic feet.

“There’s a lot of conservatism right now,” he said in an interview with CNNMoney. “We’re just at the very tip of this pyramid.”

What We Use it For

Natural gas can be used for many things – to power cars, heat homes, cook, or generate electricity.

It’s this last use that will likely represent the biggest opportunity for gas in the next couple of decades.

For the last several years utilities have scrapped plans to build coal-fired power plants in favor of natural gas plants, which emit about half the carbon dioxide, a major greenhouse gas. This move has become known in the power industry as the “dash to gas.”

But that dash has been only half-hearted, said Peter Tertzakian, chief energy economist at ARC Financial, a Calgary-based private equity firm.

Over a decade ago utility execs were promised natural gas would be abundant and cheap. But the production didn’t pan out as planned, and gas prices spiked even before oil prices did earlier this decade.

Prices have since dropped significantly, partially due to all the new shale gas, but utility execs are still leery this resource is for real.

‘It’s a question of believing,” said Tertzakian, who also thinks the estimates for future natural gas use are low. “Once they believe the trend, gas demand is more likely to gain momentum.”

One company that seems to believe is Exxon Mobil.

Late last year, Exxon (XOM, Fortune 500), the world’s largest publicly traded oil company, paid $41 billion for XTO (XTO, Fortune 500), a natural gas company that primarily operates in the Untied States and is big player in the shale area.

Many analysts took Exxon’s entry into this space as a sign that the shale gas boom is here to stay.

“They don’t move fast and they aren’t leading edge, but they don’t make a lot of big mistakes,” said Tommy Mann, global head of natural gas at the consulting firm Accenture. “If Exxon is looking at it, there must be something there.”

What it Changes

If natural gas use spreads substantially, its growth will likely be in the power sector.

While it can be used in cars, most analysts say that beyond use in busses or fleet vehicles that have set routes, the infrastructure really isn’t there to support widespread use in cars. And the heating market is fairly well tapped.

But in making electricity, it could have real benefits. Ming, from Secure Energy, said that used in the most efficient power plants, natural gas is actually 70% cleaner than coal.

He is promoting an effort to replace the oldest, dirtiest 30% of the country’s coal- fired power plants with natural gas, a move he says would shave almost 10% off the country’s total greenhosue gas emissions.

Coal power plants will still exists, but impacts from cheap, widespread natural gas are clear.

“The real loser is coal,” said Noel Tomny, head of global gas at the energy consultants Wood Mackenzie.

As for the environment, many say a move to natural gas is a good thing but doesn’t replace the need to build more renewables and ultimately get fossil fuels out of the electricity generation business all together.

“Gas doesn’t get us there,” said Dave Hamilton, director for global warming and energy projects at the Sierra Club, referring to the 80% drop in emissions most scientists say are needed by 2050 to avoid the worst effects of global warming.

It may not get us there. But without huge advances in renewable energy, removing all fossil fuels from the electricity market will be a tough proposition. Gas may be the next best thing.

By Karl Mortished in The Times

Carbon dioxide is dangerous, says Lisa Jackson, administrator of the US Environmental Protection Agency (EPA). It is dangerous, like the growling exhaust pipe of a 25-year-old Chevy Corvette or the sulphurous plume from a coal-fired power station. Overnight, America has decided: carbon-dioxide pollution is a public health hazard and emitters will be shunned like cigarette smokers.

The EPA’s decision on Monday to treat CO2 as if it were a noxious poison was craved and dreaded in equal measure by climate activists and industrialists. It is a bombshell, more than just a public relations ploy to make President Obama look cool at the Copenhagen summit. It unleashes one of the toughest US regulators and gives it a mandate to go after heavy industry with compliance orders and fines. Power generators, oil refiners, chemical manufacturers and cement makers have been warned: the bloodhounds of the EPA will hunt you down and curb your emissions.

This is politics, of course. A lot must happen before the EPA begins to slap fines on recalcitrant power companies. The agency needs to draw up regulations that work — a monumental task. It needs to decide which CO2 abatement technologies are effective and affordable — at present, there are no commercial carbon-capture technologies, only government-subsidised pilot projects.

But make no mistake: this is the beginning of America’s puritanical crackdown on carbon. If you are surprised that the atmospheric gas that feeds the roses in your garden is being labelled a dangerous poison, remember that America doesn’t regulate its citizens with the gentle persuading hand of the Queen; it does so with the passion of the religious convert. If the EPA is unchallenged, carbon will be hunted down, in the tailpipes of cars in Los Angeles and in the stacks of power plants in Virginia.

America’s electricity industry has reacted with alarm to Ms Jackson’s decision. The US is mostly powered by coal, a fossil fuel that accounts for 80 per cent of America’s abundant greenhouse gas emissions. America has enormous coal reserves — indeed Warren Buffett has just made a big bet on the coal industry, buying a controlling interest in Burlington Northern Santa Fe, a railroad group that trucks coal from mines in Wyoming to Texas and southern California.

There is an alternative to the EPA’s bloodhounds: two climate change Bills making their way through the US Congress would create cap-and-trade systems to offer incentives to industry to curb emissions. The two Bills are similar and both give huge exemptions to power companies in the form of free emission allowances. The American legislation is, in microcosm, what a new Copenhagen climate treaty might look like: a hotchpotch of complex regulation, extravagant concessions, get-out clauses and bribes to politically sensitive groups.

On the one hand, America has the hydroelectric-powered Washington State, where Democratic Senator Maria Cantwell waves the climate-change hockey stick. At the other end of the country, you have coal-fuelled states, such as Georgia, where a federal tax on top of the monthly utility bill spells political death. So, inequality in the carbon burden means taxing Pacific Coast liberals in order to subsidise coalmining rednecks.

It begs the question whether a climate change Bill is possible. That is where the threat of the EPA looms. In a landmark case in 2007, the Supreme Court found that CO2 was an air pollutant within the meaning of the America’s Clean Air act, opening the door for Monday’s statement by Ms Jackson. Climate activists have been waiting for this moment, when the EPA would aim its guns at Big Oil and Big Coal.

Mr Obama is probably not keen to let the EPA do its job. It would be a blunt instrument and politically dangerous, for the important reason that the EPA would be “fair”. Unlike a congressional Bill, with its tweaks, trade-offs and bungs, the EPA would regulate carbon, everywhere. There would be no concessions: every tonne, whether emitted by car, cow or chemical plant, would have to be measured and fined.

The impact on US industry would be harsh and investment would flee from energy-intensive industries. Carbon leakage to Asia would become a flood and, quickly, a hue and cry would build for stringent US tariffs on Chinese goods.

There would be another important consequence of an EPA audit of US industry and that would be a huge rush to natural gas. Coal has secured a get-out for the time being in the congressional Bills. Without special treatment, however, the only quick lower-carbon solution available to US power utilities is huge investment in efficient gas-fired generation plant. Gas produces a third of the CO2 emissions of coal and, after new discoveries, gas in the US is extremely cheap. If Ms Jackson has her way, this could be America’s big dash for gas.

carl.mortished@thetimes.co.uk

By Kate Galbraith and Felicity Barringer for the New York Times

The Environmental Protection Agency, about to declare heat-trapping gases to be dangerous pollutants, has embarked on one of the most ambitious regulatory challenges in history.

The move is likely to have a profound effect across the economic spectrum, affecting transportation, power plants, oil refineries, cement plants and other manufacturers.

It sets the agency on a collision course with carmakers, coal plants and other businesses that rely on fossil fuels, which fear that the finding will impose complex and costly rules.

But it may also help the Obama administration’s efforts to push through a federal law to curb carbon dioxide emissions by drawing industry support for legislation, which many companies see as less restrictive and more flexible than being monitored by a regulatory agency. And it will lay a basis for the United States in the negotiations leading up to a global climate treaty to be signed in Copenhagen in December.

Once made final, the agency’s finding will pave the way for federal regulation of carbon dioxide, methane and other heat-trapping gases linked to global warming.

In practical terms, the finding would allow quick federal regulation of motor vehicle emissions of heat-trapping gases and, if further actions are taken by the E.P.A., it could open the doors for regulatory controls on power plants, oil refineries, cement plants and other factories.

On Friday, the E.P.A. sent its finding to the Office of Management and Budget for review, according to a Web site that lists pending federal rules. Once the budget office clears the finding, it can be signed by the E.P.A.’s administrator, Lisa P. Jackson. There is also likely to be a public comment period on the proposed finding, but there is wide expectation that it will be put in place.

Some policy makers greeted the agency’s action as the first step in a new approach to climate change.

“This finding will officially end the era of denial on global warming,” Representative Edward J. Markey, a Massachusetts Democrat who leads a select committee on global warming, said in a statement.

But Bill Kovacs, a specialist on global warming issues with the United States Chamber of Commerce, said that an endangerment finding would automatically provoke a tangle of regulatory requirements for businesses large and small.

If finalized, the finding by the agency could lead to a vast extension of its reach. Much is unknown about the details of what the E.P.A. is proposing, including how stringently the agency would regulate the emissions and how it would go about doing so.

But in February, Ms. Jackson indicated she was aware the agency could be stepping into a minefield by issuing such a finding. “We are poised to be specific on what we regulate and on what schedule,” she said at the time. “We don’t want people to spin that into a doomsday scenario.”

Experts said Monday that the E.P.A.’s action would put pressure on Congress to pass federal legislation that could supplant the agency’s plan or guide how it was carried out. A federal bill is preferred by many environmentalists and policy makers, as well as by industry.

John D. Walke, a senior lawyer at the Natural Resources Defense Council, said he welcomed the agency’s decision but hoped it would ultimately lead to federal legislation.

“For some period we may have parallel efforts of Environmental Protection Agency pursuing or even adopting regulation while the eventual main show will be in Congress,” Mr. Walke said.

Still, many doubt that legislation to cap emissions can pass this year, in the midst of a recession and at a time when carbon dioxide emissions are down because production is lower.

The E.P.A.’s move is the latest in a flurry of proposals that signal its determination to break from the Bush administration, which infuriated environmentalists by sidestepping the issue of regulating heat-trapping gases.

Earlier this month, the agency proposed creating a greenhouse-gas emissions registry, which would require industries — including oil refineries and cement makers, as well as utilities and pulp and paper manufacturers — to report how much pollution they were emitting.

The endangerment proposal is another step. In 2007, the Supreme Court ordered the E.P.A. to determine whether carbon dioxide and other heat-trapping gases qualified as pollutants under the Clean Air Act. Ms. Jackson, the agency’s administrator, suggested to The New York Times in February that she hoped to act on emissions of heat-trapping gases by early April, before the second anniversary of the court’s ruling.

The Bush administration had stalled in complying with the court order, opting for more study of the issue, although there was wide consensus among E.P.A. experts that a determination that carbon dioxide was a danger to the public was supported by scientific research.

Asked about the E.P.A.’s move, the White House press secretary, Robert Gibbs, emphasized the importance of going through Congress. “The way to deal with greenhouse gases,” Mr. Gibbs said, “is to work with Congress in order to put together a plan that deals with this and creates a market for renewable energy.”

There are several reasons that there is a widespread preference for a legislative “cap-and-trade” approach to regulating carbon dioxide emissions, as opposed to E.P.A. regulation.

A central reason, said Paul Bledsoe of the National Commission on Energy Policy, is that Congressional action is less subject to litigation and could not be easily overturned by a new administration.

But a deeper concern among the industry is that regulation by the E.P.A. is a blunt tool. The agency’s regulatory powers have previously been applied mainly to pollutants that do damage on a regional level, like nitrogen oxide and hydrocarbons.

By contrast, carbon dioxide, methane and other heat-trapping gases that the E.P.A. proposes to regulate do harm on a global scale.

“The act does not deal well with an emission that’s virtually ubiquitous and travels through the atmosphere,” said Carol Raulston, a spokesman for the National Mining Association, a coal industry group.