Does biomass power increase carbon emissions?

Does wind power increase carbon emissions? That was the question I asked in a recent post after seeing a analysis by Stanley Rhodes of Scientific Certification Systems, a major testing and certification agency for green building products, among other things. Stanley, who is a respected expert on life-cycle assessment, looked beyond the carbon emitted directly by wind power operations to carbon emitted as a result of having wind power in the mix.

The same type of analysis draws into question the environmental benefits of biomass power, and I recently found more information on the topic. The chart shows an Environmental Performance Declaration for the Mt. Shasta Woody Biomass Plant, a 50-megawatt plant in California. In this case, the biomass is woodchips from forests in the region.

Note the high impact levels for terrestrial habitats, wetland habitats, and key species, and the substantial impact for emissions categories including cumulative greenhouse gases, smog, and soot.

In his presentation (link to PDF) at Greenbuild 2007, Rhodes gave the following reason for why biomass power, at least in this case, has substantial and sometimes greater environmental impacts compared with the standard electrical mix, which is mostly derived from fossil fuels. To quote from his slides:

• Habitat disruption from forestry operations at least 1,000 times greater than caused by the average power mix on an equivalent power production basis.
• Smog/PM/TCDD emissions related to human health are exposing surrounding populations above threshold levels.
• Reduced carbon storage per hectare due to removal of fuel loading to control fire danger led to 30% reduction in net carbon storage.
• Wood chip piles at biomass operations were found to biodigest during storage, resulting in significant methane releases. These releases were found to cancel 40% of the total carbon neutral potential.

In fairness, the analysis shows that the biomass plan has low impacts in terms of fossil-fuel depletion, radioactive-waste generation, water consumption, and other categories.

But in general, as we look to replace fossil fuels, we need to be careful to recognize the costs of renewable sources. Let's not eat a free lunch and pass the bill to other species and future generations.

The chart, by the way, is an example of an intriguing new way of presenting environmental impacts of products in a scientifically rigorous but easily accessible format. I have more discussion of this and another example in this post.