Last summer, EPA temporarily exempted the carbon emitted from burning biomass from pollution standards under the Clean Air Act and convened a panel of scientific experts to advise it on crafting rules for the treatment of biomass.
Last week, that Science Advisory Board released its long-awaited draft evaluation of EPA’s proposed Accounting Framework for Biogenic CO2 Emissions from Stationary Sources. [Note, this report is not final and meant only as a deliberative draft.] Here’s our first read:
In its report, the SAB determines several scientific principles to guide EPA, which we believe will be critical to biomass regulations going forward.
First, it issues a clear and unequivocal rejection of the idea that biomass can automatically be treated as carbon neutral. As we discuss here, the lifecycle carbon emissions of some forms of biomass are neutral or close to neutral over a reasonable period of time—meaning that they completely balance the production and use of carbon, resulting in zero net emissions. Feedstocks like landfill gas, forest and crop residues that would otherwise be burned, and annual crop residues not needed to preserve soil carbon stocks, have low net emissions within very short periods of time and can reasonably be considered potential low-carbon alternatives to fossil fuels like coal. On the other hand, net carbon emissions from harvesting and burning whole trees and other similar forms of biomass will result in as much if not more carbon emissions than burning coal for decades.
The SAB appropriately concludes that:
“Only when bioenergy results in additional carbon being sequestered above and beyond the anticipated baseline (the “business as usual” trajectory) can there be a justification for concluding that such energy use results in little or no increase in carbon emissions.”
What that means is that only biomass that is carefully chosen, grown responsibly, and efficiently converted into energy can reduce carbon pollution and other emissions compared to fossil fuels.
Second, the SAB offers a blunt critique of EPA’s regional approach to assessing the carbon impacts of bioenergy, concluding that it is scientifically unjustified. In its draft Accounting Framework, the EPA proposes to adjust the carbon emissions of large, biomass-burning facilities by a regional “Biomass Adjustment Factor” based on an assessment of forest stocks in the region where the facility is located. This approach, according to the SAB, is a “central weakness of the Framework” and “leads to the nonsensical conclusion that a ton of carbon emitted in one part of the country may be treated differently from a ton of carbon emitted elsewhere.”
If applied, this type of regional approach would mean that a power plant burning whole trees from a given region would have zero “net biogenic emissions” as long as total tree harvesting in that region doesn’t exceed annual forest growth. Yet, from the perspective of the atmosphere, eliminating a carbon sink has the same impact as creating an equivalent-sized smokestack. So plants burning biomass cannot be given credit for forest growth and carbon sequestration that would be happening anyway without increasing net carbon emissions to the atmosphere. Not only would this approach create perverse incentives for investors and land-owners, but it ignores the actual ways in which bioenergy producers can affect carbon emissions: by choosing low-carbon feedstocks from lands that are sustainably managed and using efficient conversion technologies to turn that biomass into electricity.
Third, the SAB recommends that EPA apply points EPA towards a “categorical inclusion” approach for power plants burning whole trees and other long carbon recovery feedstocks. Under such a system, 100% of the carbon emitted at biomass burning facilities would be counted, with the burden of proof resting with power plants to demonstrate any additional carbon sequestration they wish to be credited for. This reaffirms the principle of starting with full carbon accounting for the vast majority of biomass and resists the notion that we should be giving large biomass-burning facilities carbon credit “on spec” for biomass regrowth they claim will happen in the future.
Asked by EPA, “Is [the draft Framework] scientifically rigorous?”, the SAB’s response could not be clearer: “The SAB did not find the Framework to be scientifically rigorous.”
As we here at NRDC have done, the SAB calls on EPA to abandon the Framework in favor of an accounting system that would be simpler to implement and could accurately assess the climate impact of burning biomass. It suggests that EPA give credit to facilities burning biomass that falls into short recovery feedstocks—things like agricultural residues, perennial herbaceous crops, mill wood wastes, and other wastes where carbon recovery and “anyway” emissions are within one to a few years—but require that emissions from all other types of biomass be fully counted at the smokestack. Facilities wishing to claim carbon credit for burning biomass would then have to demonstrate that the biomass they’ve sourced has actually resulted in a reduction in carbon emissions to the atmosphere.
The SAB offers two options for doing so: sustainable certification and carbon offsets. On its own, sustainable certification does not tell us about the carbon impacts of any source of biomass. And for its part, crediting carbon for completely unrelated projects meant to offset emissions from the smokestack would only add an additional layer of complexity and uncertainty into the system, given the challenges of ensuring that offset credits represent real, additional, and verifiable carbon sequestration.
However, certification coupled with rigorous carbon sequestration accounting could be used to assess the carbon impacts of specific biomass feedstocks sourced from specific landscapes. Critically, this would mean a system that credits only sequestration above and beyond what would have happened anyway on the landscape from which the facility is sourcing biomass—for example, through management changes that result in greater biomass growth or new tree plantings where trees otherwise would not be growing—and has mechanisms in place to account for emissions leakage to other landscapes, as well as the risk of reversal.
We need a regulatory system that links emitter behavior directly to what’s happening on the landscape, putting in place the necessary market incentives to encourage bioenergy facilities to source low-carbon biomass and burn it efficiently. The SAB’s draft report is correct in concluding that EPA’s Framework fails to offer a scientifically rigorous and workable approach to regulating biogenic carbon. NRDC applauds the SAB’s work to date in reinforcing key scientific principles in biomass carbon accounting and urges it to further elaborate effective approaches for implementing these principles.