Skip to main content
Categorized under: Bioenergy, Policy

Render Unto Science: Biomass Carbon Emissions Should Be Determined by Science, Not Congressional Fiat

The Senate Appropriations Committee’s vote to disavow the seemingly indisputable fact that forest biomass-based energy generation emits carbon dioxide is a short-sighted attempt to legislate science. The bill would openly set aside scientific consensus in favor of an edict that the industrial-scale combustion of trees and other biomass is essentially “carbon neutral” and thus “do not require regulation, control, or action.”

The Interior, Environment, and Related Agencies spending bill that passed out of committee on June 16, 2016, requires the US Environmental Protection Agency to actively ignore research showing that biomass combustion typically causes a net increase in atmospheric carbon dioxide levels for decades (even when any subsequent regrowth of harvested forestland is taken into account).

Biomass power plant photo: Paul Glazzard,

Determining the particular lifecycle impact of different forms of bioenergy on climate change can be complicated. But scientists have repeatedly told Congress and other policymakers that there’s no scientific basis for broadly assuming that biomass combustion is “carbon neutral.” In June 2014, 91 scientists told EPA:

[T]he carbon dioxide (CO2) emitted by biomass-fired stationary sources has often been ignored in regulatory contexts, usually on the assumption that biomass regrowth would quickly reabsorb the CO2 emitted by the facilities. As the EPA has itself determined, that assumption is misguided.

In February 2016, 65 scientists reiterated that message to the Senate:

Mandating that there are no carbon dioxide emissions from burning wood from forests to produce energy does not make it so in fact … Legislating scientific facts is never a good idea, but is especially bad when the ‘facts’ are incorrect.

Earlier this month, Professors Mark Harmon and Bev Law of Oregon State University wrote:

The [carbon neutrality] bills’ assumption that emissions do not increase atmospheric concentrations when forest carbon stocks are stable or increasing is clearly not true scientifically. It ignores the cause and effect basis of modern science. Even if forest carbon stocks are increasing, the use of forest biomass energy can reduce the rate at which forest carbon is increasing. Conservation of mass, a law of physics, means that atmospheric carbon would have to become higher as a result of this action than would have occurred otherwise. One cannot legislate that the laws of physics cease to exist, as this legislation suggests.

A panel of experts convened by EPA under the auspices of its Science Advisory Board has repeatedly reminded the Agency that “carbon neutrality is not an appropriate a priori assumption,” but rather “a conclusion that should be reached only after considering a particular feedstock’s production and consumption cycle.”

Fortunately, the Obama Administration understands that complex carbon accounting issues should be addressed with science, not by fiat. Faced with similar “carbon neutrality” language in last year’s House Appropriations bill, the White House objected that the bill’s treatment of forest biomass as “categorically ‘carbon-neutral’

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.”

Rather than continue to indulge misguided attempts to “legislate that the laws of physics do not exist,” members of Congress should abandon broad “carbon neutrality” legislation and instead work with EPA, states, industry, and environmental stakeholders to ensure that the Clean Power Plan and other federal policies apply a scientifically-defensible approach for determining the actual amount of CO2 emitted by biomass-burning facilities.

Any legislative proposals that emerge should be taken up in committees of jurisdiction—not in Appropriations—so that the merits of different approaches can be considered at open hearings with help from expert witnesses. The experts are likely to explain that burning forest biomass emits “substantially more carbon dioxide per unit of electricity” than burning coal or natural gas; that those additional CO2 emissions will result in higher levels of atmospheric CO2 “for many decades to a century;” and that cutting down forests to supply bioenergy facilities could cause “a significant depletion” of our national forest carbon sink, one of the best tools the United States has for limiting CO2 buildup.

The experts might also discuss scientific studies that identify biomass-based power systems that may offer climate benefits within a relatively short period, such as co-generation plants that combust certain “residues from ongoing harvest operations for traditional wood products (lumber and pulp) and application of intensive silviculture to regeneration of harvested stands.” The process of identifying comparatively helpful types of bioenergy requires careful analysis.

Which brings us back to the larger point: we can’t address climate change by ignoring science. CATF and dozens of other public interest groups urged Senate appropriators to exclude “any anti-environmental riders in this year’s appropriations bill that threaten our air, land, water and wildlife, including riders that would fail to account for the carbon pollution emitted by biomass power facilities.” We appreciate the efforts by Senator Tom Udall and others to strike the riders from the bill, and we renew our appeal to the rest of Congress and to the Obama Administration to block this attempt to legislate science.