Report finds biomass emits significantly less CO2 than coal

By Lisa Gibson | August 15, 2011

A life-cycle assessment comparing biomass power to coal power shows biomass emits just 4 percent of the carbon dioxide coal power emits. The conclusion is one of many resulting from “Life Cycle Impacts of Forest Management and Wood Utilization on Carbon Mitigation: Knowns and Unknowns,” a recently released study by lead author Bruce Lippke, of the University of Washington’s College of Environment, as well as other contributing authors. The report also found that sustainably managed forests are better than carbon neutral, and managed forests continually accumulate carbon and maintain stable carbon stocks.

The findings are significantly different from those of the 2010 Manomet Center for Conservation Sciences study, which concluded that biomass power initially emits more carbon per unit of energy than coal, accruing a carbon debt that is paid off as the forest continues to grow and recapture carbon. Lippke’s group is not the first to offer a counter to the claims made in the Manomet study, pointing out that equating biomass carbon and fossil fuel carbon can give rise to concerns about the immediate release of carbon from burning biomass as opposed to slower releases as would occur during decomposition on the forest floor. “While much has been made about this time sensitivity—that burning wood is worse than letting it decay—the longer term benefits of sustainable wood production displacing fossil fuel emissions rotation after rotation far outweighs any short-term impact,” the report states. The view is similar to that of William Strauss, president of FutureMetrics, whose analysis found that there is no carbon debt, but instead a credit of previously-accumulated carbon.

Both conclusions tout the idea that sustainably managed forests provide the opportunity to sustain a maximum rate of carbon absorption, and are essentially carbon neutral. “The life-cycle research results accumulated over the last decade does not lead one to assume forest carbon neutrality, rather it demonstrates that the emissions from burning biomass for energy and the products produced from forest removals are being offset by the sustained growth in forest carbon removed from the atmosphere even after deducting any emissions from unused dead wood left in the forest,” according to Lippke’s study.

Natural disturbance is also a concern addressed in the report, but it states that there are higher risks of carbon loss due to natural disturbance in unmanaged forests than in managed forests. And collecting that biomass as a forest management practice requires little energy and releases little emissions, Lippke and his fellow researchers wrote.

Check out the study here.