All Biofuels Are Not Equal
In Washington, 90 U.S. scientists wrote to House Speaker Nancy Pelosi and Senate Majority leader Harry Reid to fix accounting standards for greenhouse gas emissions associated with bioenergy projects.
The scientists said they wanted to correct a perception that “all biofuels and bioenergy are equally good for the environment and are all lower in carbon emissions than fossil fuels.”
Signatory William Schlesinger, president of the Cary Institute of Ecosystem Studies, said, “If our laws and regulations treat high-carbon-impact bioenergy sources, like today’s corn ethanol, as if they are low-carbon, we’re fooling ourselves and undercutting the purpose of those same laws and regulations.”
The letter appears to be directly aimed at amending what the scientists perceive to be loopholes in the American Power Act, introduced in the Senate by John Kerry of Massachusetts and Joe Lieberman of Connecticut.
The scientists wrote: “Bioenergy can reduce atmospheric carbon dioxide if land and plants are managed to take up additional carbon dioxide beyond what they would absorb without bioenergy. Alternatively, bioenergy can use some vegetative residues that would otherwise decompose and release carbon to the atmosphere rapidly.
Whether land and plants sequester additional carbon to offset emissions from burning the biomass depends on changes both in the rates of plant growth and in the carbon storage in plants and soils. For example, planting fast- growing energy crops on otherwise unproductive land leads to additional carbon absorption by plants that offsets emissions from their use for energy without displacing carbon storage in plants and soils.
On the other hand, clearing or cutting forests for energy, either to burn trees directly in power plants or to replace forests with bioenergy crops, has the net effect of releasing otherwise sequestered carbon into the atmosphere, just like the extraction and burning of fossil fuels. That creates a carbon debt, may reduce ongoing carbon uptake by the forest, and as a result may increase net greenhouse gas emissions for an extended time period and thereby undercut greenhouse gas reductions needed over the next several decades.”
Citing Land Clearing and the Biofuel Carbon Debt, as published in Science in 2008, the group said “any legal measure to reduce greenhouse gas emissions must include a system to differentiate emissions from bioenergy based on the source of the biomass. The National Academy of Sciences has estimated significant potential energy production from the right sources of biomass4. Proper accounting will provide incentives for these sources of bioenergy.”
Reaction from the Natural Resources Defense Council
Nathanael Greene, of the Natural Resources Defense Council, commented: “Today a group of leading scientists from across the country sent a letter to congressional leaders and Obama officials urging them to carefully count the carbon from biomass burned for energy as part of a comprehensive climate bill or any other legislation or regulation.
The American Power Act (APA) proposed by Senators Kerry and Lieberman provides a solid framework for reducing our global warming pollution and investing in a cleaner economy. Unfortunately, as proposed, the bill would turn a blind eye towards emissions from biomass combustion, threatening to significantly undermine the bills carbon reduction goals. (For some basic thoughts on how the bill should be amended see this fact sheet put out by NRDC and other groups after the House climate bill passed.)
I did a little video late last year explaining the fundamental flaw in the approach that the APA would take. The letter from the scientists puts it clearly: Replacement of fossil fuels with bioenergy does not directly stop carbon dioxide emissions from tailpipes or smokestacks. Although fossil fuel emissions are reduced or eliminated, the combustion of biomass replaces fossil emissions with its own emissions (which may even be higher per unit of energy because of the lower energy to carbon ratio of biomass).
Bioenergy can reduce atmospheric carbon dioxide if land and plants are managed to take up additional carbon dioxide beyond what they would absorb without bioenergy. On the other hand, clearing or cutting forests for energy, either to burn trees directly in power plants or to replace forests with bioenergy crops, has the net effect of releasing otherwise sequestered carbon into the atmosphere, just like the extraction and burning of fossil fuels. That creates a carbon debt, may reduce ongoing carbon uptake by the forest, and as a result may increase net greenhouse gas emissions for an extended time period and thereby undercut greenhouse gas reductions needed over the next several decades.
Out Take: ”Round up the Usual Suspects.”
The letter was signed by seven members of the National Academy of Sciences and a Nobel Peace Prize co-laureate. and should be taken seriously as a point of view in science, and certainly as a political act.
This letter represents scientists, but does it represent science? Imagine what a country the United States would have turned out to be if every U.S. state ratified a different Constitution.
It was primarily signed by biologists and ecologists and did not include leading scientists noted in the development of bioenergy technologies — such as George Church, Chris Somerville, Bruce Dale, Lee Lynd, or Charles Wyman to cite a few examples. A letter signed by a more inclusive group of scientists would have done more to dispel the sense that this letter represents a narrowly-held view within the scientific community, rather than consensus, and consensus must be the basis of any renewable energy policy which would provide any of the benefits of policy stability that renewables as a sector unequivocally require.
Give me Liberty or Give me Death: Give Us Unity or We’ll Face Dearth
The Digest urgently calls on its friends in the scientific community, through the National Academy of Sciences, or other appropriate vehicles, to develop a point of view which can be generally said to be representative of a broad scientific consensus. We have seen what a lack of consensus can do to side-track the discussion of climate change.
Whatever the consensus is, let the chips fall where they may.
Renewable energy needs stability, not a series of partisan letters from open side of the table that can be expected to be answered with a parallel set of letters from the other. That’s ping-pong, not policy, and the time for games has long since passed.
A copy of the letter is available here.