With the focus on renewable energy, combustion of biomass is receiving increased interest as a clean fuel alternative. In theory, biomass combustion uses a renewable resource (such as wood) and is carbon neutral. However, recent permitting-related actions show that biomass combustion can be as controversial as the use of other fuels and questions are being raised about its carbon-neutrality claim.

The issue of whether biomass combustion is, in fact, carbon neutral recently arose in the recent U.S. EPA Advisory Committee addressing greenhouse-gas air permitting under the Clean Air Act. The principle of carbon neutrality is based on the notion that trees and plants remove carbon through photosynthesis, and the stored carbon is then released when biomass is combusted. Thus, no new carbon is added to the atmosphere when biomass is burned. Recent “life cycle” calculations brought forward by environmental groups question this notion of carbon neutrality, and U.S. EPA is re-evaluating whether to grant biomass combustion an automatic exemption as part of its new greenhouse-gas permitting requirements. If the automatic exemption does not apply to biomass, those facilities will have to assess best available control technology for greenhouse-gas emissions, like other combustion units, and face an uncertain and potentially difficult task.

The use of biomass as a fuel also is creating significant divides between those using biomass (such as wood) as part of the forest products industry (paper, construction materials) and utilities that combust wood for energy. The paper industry intervened in a state public utility commission proceeding in opposition to a proposed biomass utility unit in Wisconsin. While the unit was eventually approved, the proceeding demonstrates that approval of a new biomass facility requires careful consideration of the fuel source and the adverse affects combustion may have on other users of wood materials.