An interesting quandary arises in considering biofuels.
On the one hand there is an accepted rule of thumb that biofuels are in principle carbon neutral – that the carbon released into the atmosphere came from the atmosphere in the first place.
On the other hand there is the accepted belief that forest clearing is an important contributor to greenhouse gas accumulation.
These basic ideas run into each other when there is wood burning used as a fuel for modern energy systems:
In a 2-1 decision [PDF], a U.S. Court of Appeals panel in the District of Columbia Circuit struck down a 2011 Environmental Protection Agency rule that deferred for three years regulating the greenhouse gas emissions from biomass burning in the same manner the agency regulates plants that burn fossil fuels.
Biomass power plants that burn forest products weren’t the only type of energy production at issue here, but they were a big bone of contention. Supporters of forest biomass – including leading liberals in the U.S. Senate like Oregon Democrat Jeff Merkley – argue that forest biomass can be far less harmful to the environment because carbon released in burning the material is matched by carbon pulled from the atmosphere by new-growing trees.
But the science is far from clear on that point and conservation groups – like the Center for Biological Diversity, which brought the suit against the EPA, and the Natural Resources Defense Council – argue that “emissions from power plants and other industrial facilities that burn biomass can accelerate global warming and contribute to a host of respiratory and cardiac problems.”
It’s tricky business on the carbon front alone. I think it’s clear that biofuels are carbon neutral on the time scale of biomass replacement. If forests regrow where forests are harvested, that is carbon neutral, though in many cases it can be very environmentally destructive in other ways. But regrowing a forest can take a very long time, and is contingent on a lot of things going right, often after something (a clearcut) has in an ecological sense gone very wrong.