Meta-Issues Related to Carbon Footprint of Biomass Used for Energy Production
The burning of biomass for electricity generation could play a role in states’ Clean Power Plan (CPP) compliance, but the U.S. Environmental Protection Agency’s guidance on what constitutes “qualifying biomass” is still pending at its Scientific Advisory Board. Discussions of biomass’s carbon neutrality can be confusing, with competing, contradictory, and polarized claims that biomass is carbon-neutral versus claims that burning biomass is worse than burning coal. This paper, produced for informational purposes at the request of the Oregon Department of Environmental Quality, shows that these competing claims are largely a result of different initial assumptions on scopes and models of the carbon cycle.
The scope and scale of analysis of biomass’s carbon footprint can lead to very different analytical outputs. Time frames can be adjusted to avoid them being unrealistically short or long, or to more appropriately reflect on-the-ground realities, such as state-level or regional harvest practices for specific types of trees and specific types of forest management. Likewise, altering the spatial scope of an analysis (a single forest stand versus a larger parcel or landscape) can make a carbon impact appear more or less severe. As the paper sets forth, baseline conditions are critical to consider to get an accurate picture of carbon impacts. The CPP does not require full life-cycle carbon footprint analysis for any type of fuel, yet every form of generation has such a carbon footprint, and this paper notes that a full consideration of it would include emissions from biomass harvesting, transportation, and processing. Likewise, an accurate comparison to coal or natural gas would require the emissions from mining or well extraction of those fuels, as well as their processing and transportation.
The paper identifies other key factors for an analysis beyond temporal and special scope and baseline conditions, including:
- Efficiency of biomass in cogeneration (for all fuels);
- Emissions displaced by substitution of biomass for other fuel;
- Sequestration of wood-biomass from more valuable portions of a harvest in wood products, including building material;
- Forest management and land use change; and
- Broader sustainability concerns.
It then uses these factors to examine existing analysis of the carbon impact of biomass and a comparison to other fuels.