Scientific and political consensus emerging: not all biomass is "carbon neutral"

When dealing with a thorny public policy issue, it's always noteworthy when scientific and political consensus begins to emerge. Last week, a number of statements out of different parts of our government showed that our understanding of the role biomass--essentially plant material burned to produce energy--can play in climate policy is beginning to converge on the same message: not all biomass is "carbon neutral". This matters because power plants looking for alternatives to burning coal and other fossil fuels are increasingly turning to burning biomass. However, while some sources of biomass fuel could be beneficial to reducing climate emissions from power emissions, others will make our carbon problem worse.

On Tuesday, the White House released an anticipated Statement of Administration Policy, outlining their opposition to (and plans to veto) the current Interior Appropriations Bill coming out of the House of Representatives. The statement covered a wide range of issues, including numerous riders that had been attached to the bill. But on the biomass front, the Administration's comments certainly jumped out at those of us who are long-time followers of the issue:

Classification of Forest Biomass Fuels as Carbon-Neutral. The Administration objects to the bill's representation of forest biomass as categorically "carbon-neutral." This language conflicts with existing EPA policies on biogenic CO2 and interferes with the position of States that do not apply the same policies to forest biomass as other renewable fuels like solar or wind. This language stands in contradiction to a wide-ranging consensus on policies and best available science from EPA's own independent Science Advisory Board, numerous technical studies, many States, and various other stakeholders.

On Thursday, Congressional voices likewise underscored that all biomass is not carbon neutral. Speaking on the floor of the House of Representatives, Virginia Congressman Don Beyer pointed to the fact that some types of biomass can reduce carbon emissions, while others can raise them. Ignoring biomass emissions here in the U.S., he said, could lead to substantial additional demand for wood--on top of massive demand being driven today by flawed European policies that do just that.

On the other side of the Capitol, members of the US Senate have also recognized that only some forms of bioenergy are generally accepted as being carbon neutral. Even in their generally pro-biomass letter, they distinguish different types of biomass, acknowledging that only "biomass derived from residuals of forest products manufacturing and agriculture" enjoys undisputed recognition as carbon neutral.

When trees and other plant materials are burned, the carbon they have accumulated over many years is released immediately into the atmosphere, just as with coal. That means that accounting for the carbon that's emitted when large power plants burn biomass will be a key part of ensuring that these new standards really do help clean up our air and climate.

What these public statements indicate is a growing understanding that some forms of biomass fuel, for example, sawdust and chips from sawmills that would otherwise quickly decompose, have the potential to reduce carbon emissions compared to fossil fuels. These are the biomass fuels we need to focus on and we need policies that encourage the biomass industry to source them.

On the other hand, burning other biomass sources, like whole trees and other large-diameter wood, actually increases carbon emissions compared to coal and other fossil fuels. Those increases can persist for anywhere from 35 to 100 years or more, depending on regional variations in climate and forest type, and would therefore make climate change worse.

In 2011, EPA committed to a science-driven process to determine how to best account for the carbon emissions associated with different biomass fuels and empaneled a Science Advisory Board (SAB) to help them in the process. As the White House statement correctly notes, the SAB rejected the idea that biomass can automatically be treated as carbon neutral and concluded that EPA must differentiate across different types of biomass:

Carbon neutrality cannot be assumed for all biomass energy a priori. There are circumstances in which biomass is grown, harvested and combusted in a carbon neutral fashion but carbon neutrality is not an appropriate a priori assumption; it is a conclusion that should be reached only after considering a particular feedstock's production and consumption cycle. There is considerable heterogeneity in feedstock types, sources and production methods and thus net biogenic carbon emissions will vary considerably.

What we're seeing emerge is a common recognition amongst leading scientific experts, the White House, and members of Congress that categorical statements about biomass either being all good or all bad just do not match what we now know based on the best available science.

Given the need to differentiate across biomass sources and get the carbon accounting right, EPA should avoid categorical statements--whether categorically positive or negative--about the role of biomass-fueled electricity when it issues the final Clean Power Plan rule next month. Instead, the most important thing EPA can do is put in place biomass carbon accounting rules that guide the biomass energy industry towards lower-carbon biomass sources like forest manufacturing waste that can help us achieve our climate goals and away from high-carbon biomass sources that could exacerbate emissions from our power sector.