For hundreds of millennia, humans have depended on wood as a basic but reliable source of fuel. Today efforts to grow that dependence in the face of an evolving energy landscape are widespread. But they’re also contentious.
The debate over biomass, an umbrella term that encompasses a range of organic materials used for energy, rests primarily on the question of “carbon neutrality.” It’s taking place at the federal level — the House Appropriations Committee voted during the summer to designate biomass “carbon neutral” — and across the states.
Massachusetts Gov. Charlie Baker announced in August that his administration would move to designate fuel derived from felling trees and clearing brush in forests as renewable energy. In Arizona the state’s Public Service recently ordered to research forest bioenergy as part of its power portfolio. The biomass industry’s main trade group is part of a just-hatched PR and advertising blitz planned for later in September by an umbrella renewable-energy consortium that also includes wind and solar and has dubbed itself National Clean Energy Week.
A small, 1,000-kilowatt-hour wood-pellet power plant — generally enough to power 1,000 homes — produces a total of 1,275 grams of CO2per kilowatt hour of electricity generated, according to Dr. Puneet Dwivedi, a research professor at the University of Georgia. In comparison, a 1,000-kilowatt-hour coal plant emits 1,048 grams of CO2per kilowatt hour — 227 grams less than the biomass plant.
So when it comes to emissions, burning coal is technically more carbon-efficient than burning woody biomass. But forests have the ability to act as a “carbon sink,” absorbing and storing the CO2 released from electricity generation. This lends credence to the claim that with appropriate forestry management, including the immediate replacement of trees that are cut down, biomass can be a “renewable” and a carbon-neutral source of energy.
The industry also claims that there would be no market for leftover logging residues if they were not used for biomass. When left on the forest floor, these organic scraps decay and emit methane, a greenhouse gas roughly 30 times more potent than CO2. On its website the Biomass Power Association states that “biomass power generates carbon-neutral electricity from natural organic waste, providing sustainable energy.” It does not qualify this claim with the aforementioned details about appropriate forestry management.
Today these nuances have rendered woody biomass an oddity in the realm of polarized debate about non-fossil-fuel sources of energy.