Substituting trees for coal in power plants would take us backwards in the fight against climate change

Last week, President Obama gave a historic speech in which he laid out his second term plan for tackling the urgent threat of climate change. Delivered from the steps of Old North at Georgetown University (making this alum very proud), I was struck by the powerful emphasis on science, speed, and investment in the clean, modern energy resources that will fuel our future.

First, in his methodic review of the data showing a rapidly warming planet, the President made clear that science, not ideology or willful ignorance must guide our policies:

"Nobody has a monopoly on what is a very hard problem, but I don’t have much patience for anyone who denies that this challenge is real. We don’t have time for a meeting of the Flat Earth Society. Sticking your head in the sand might make you feel safer, but it’s not going to protect you from the coming storm. And ultimately, we will be judged as a people, and as a society, and as a country on where we go from here."

Second, Obama underscored the need to move swiftly to address this challenge. Indeed the very title of the speech was “We Need to Act”.

Third, he linked his blueprint for curbing emissions from dirty energy sources like coal-fired power plants directly with an ambitious plan for investing in energy efficiency and the clean energy resources that will fuel our future:

"This plan begins with cutting carbon pollution by changing the way we use energy -- using less dirty energy, using more clean energy, wasting less energy throughout our economy."

Power plants are America’s biggest global warming polluters. The centerpiece of President Obama’s plan is a directive to the EPA to finalize carbon emissions standards for new power plants under the Clean Air Act and issue standards for 1,500 already operating fossil fuel plants that are currently allowed to dump unlimited amounts of carbon dioxide into our atmosphere.

An issue critical to the success of this effort is how biomass is ultimately treated under EPA's rules.

Until recently, burning biomass—essentially plant material—for energy was considered renewable. The idea was to make energy out of unused wood scrap and residues that would otherwise go to waste, and in doing so avoid burning fossil fuels.

On a small scale, this can be done responsibly. However, facing pressure to find alternatives to fossil fuels like coal, large utility-scale power plants are increasingly turning to burning biomass. Because there isn’t nearly enough wood scrap to meet the demand, whole trees are being harvested, made into wood pellets, and burned in power plants both here and abroad.

In Europe and many U.S. states, biomass is considered a “green” form of energy, with little differentiation between biomass types. As a result, power companies are being encouraged—and often subsidized—to burn even unsustainable types of biomass like whole trees, all under the guise of being “carbon neutral” and good for the planet.

Multiple landmark studies have shown that far from being "carbon neutral", whole tree biomass-fired power generation increases carbon emissions for decades when compared with fossil fuels. Here at NRDC, we’ve created this interactive graphic to help explain why:

For years, the biomass energy industry has argued that cutting and burning trees for energy reduces carbon emissions compared to fossil fuels since forests can re-grow. By substituting in trees, biomass-burning plants can avoid fossil carbon emissions. But just like coal or any other fossil fuel, when trees are burned in power plants, the carbon they have accumulated over long periods of time is released. The difference is that trees are half water by weight, which means there’s less potential energy per unit of carbon emissions in biomass energy than in fossil fuels like coal. This makes biomass facilities far less efficient than fossil fuel plants. To get the same amount of energy, you have to burn a lot more trees, emitting about 40% more carbon into the atmosphere per unit of energy generated. 

At the same time, when we harvest our forests for biomass, we destroy one of our best weapons in the fight against climate change.

Today the United States is the second largest emitter of greenhouse gases, accounting for roughly 1/5th of the world’s fossil carbon emissions. As the President made clear, there’s a lot of work to be done in bringing those emissions down. But our forests are doing a lot of heavy lifting for us on that front. 

According to EPA’s annual greenhouse gas inventory, U.S. forests generated enough net carbon sequestration in 2011 to offset roughly 13% of total U.S. carbon dioxide emissions each year—a massive carbon sink that we need to protect and expand if we are to achieve our emissions reduction goals. 

So using trees for utility-scale power generation not only releases more carbon at the smokestack, but also degrades our carbon sinks. Despite some regional variations in climate and forest type, study after study has shown that burning trees in power plants increases emissions relative to fossil fuels for anywhere from 50 to 100 years or more. And according to a new study by Dartmouth College, which I discussed here, harvesting trees disturbs carbon in the soil, releasing even greater quantities of carbon dioxide into the atmosphere than previously thought.

President Obama said we have to act now. And he was right. We don’t have decades to wait to start seeing carbon benefits.

The EPA is currently determining how to regulate biomass-burning facilities, what limits to place on its use, and how to account for biomass carbon emissions. In that process, there is no scientific justification for ignoring the carbon emissions that come from biomass-burning power plants. This is carbon that was isolated from the atmosphere before being burned for energy and its emission has the same global warming impact as the fossil carbon released when we burn coal.

As we account for our national emissions—and track our progress in meeting our emissions reduction targets—that carbon loss must either be counted when the tree is harvested or it must be counted when it goes up the smokestack. Ignoring these biomass carbon emissions risks compromising the very goals the President set forth. In could mean we clamp down on carbon pollution from burning coal, but end up increasing carbon emissions and destroying fragile ecosystems that are part of our natural heritage.

Following the President's speech, the American Forest & Paper Association weighed in on EPA's process:

"EPA’s upcoming framework and regulations on biogenic carbon will provide an excellent opportunity for the agency to recognize the positive contributions of paper and wood products manufacturers to sustainability."

The fact is, the very best thing the agency can do is recognize that our forests are one step ahead of us. They are already answering the President's call to act now, doing their part every day to help us fight climate change just by being forests: giant, super effective carbon sucking machines. And any alternative climate mitigation purpose the biomass energy industry would like to put them towards has to be compared to what would happen if we simply let them be. 

Our forests aren't fuel. In 2013, we can do better than burning trees for energy. We need to replace our coal fired power plants with energy efficiency and clean power, not dirty biomass. Electricity generation fueled by short-rotation crops, wood waste and reclaimed wood, and timber harvest residues (tops and branches) can reduce carbon emissions and represents an appropriate alternative fuel source. Together with investments in real clean energy like solar, wind and geothermal, these resources will form the 21st century energy system we need to bring down carbon emissions to levels that avoid the worst consequences of climate change. 

About the Authors

Sasha Stashwick

Senior Advocate, Energy & Transportation and Food & Agriculture programs

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