A study commissioned by MA Department of Energy Resources and released today reaches the conclusion that burning trees to make electricity is worse for the climate than burning coal at least through 2050. In fact, the study by the Manomet Center for Conservation Science finds that between the release of carbon when trees are burned and the slow reabsorption as the trees regrow, that this source of biopower would increase emissions by 3% compared to coal power over 40 years.
This will come as a shocker to some, but it really shouldn't. Wood contains less energy per pound of carbon, and forests — especially in the northeast — grow slowly. So when we burn a tree, we're releasing more carbon and getting less energy than we would if we burned coal and then re-absorbing that carbon very slowly.
In other words, not only is biopower from trees not carbon neutral, it's worse for global warming than the worst fossil fuel. This myth of carbon neutrality has been a big part of the biomass industry's lobbying. It came up from surprising and unfortunate corners in yesterday's Senate vote to protect EPA's ability protect our air quality. Hopefully this report will put an end to the silly idea.
But in busting the myth, we have to be careful that we not ignore some of the reports conclusions or overstate them. For instance, this AP story ignores the conclusion that using trees for combined heat and power can provide a 25% reduction in GHG emission compared to oil. Furthermore the report doesn't look at carefully sourced wastes and residues or biomass grown on fallow or degraded lands.
The right lesson for policy makers to take from this study is that we have to carefully account for the carbon associated with bioenergy. I've written about the importance of getting this accounting right before and just recently 90 scientists called on Congress to get it right in climate legislation and energy policy. Efficient uses of the right sources of biomass can provide an important supply of low carbon energy, but you don't get that if you pretend that it's all the same let alone all carbon neutral.