Wood Bioenergy: What is the “Biogenic Carbon Cycle”?

13 10 2011

Earlier this year, the EPA deferred a final decision on how to regulate greenhouse gas (GHG) emissions from wood-using bioenergy facilities.  Why?  EPA wants to study further the research on carbon accounting and the carbon neutrality of biomass.  (While clearly an important topic for additional study, the research posted on CNN this morning about the female orgasm looks more interesting…..I’m just saying).

The idea that forest biomass is carbon neutral when used for energy stems from its natural role in the biogenic carbon cycle.  What’s that?  In the biogenic carbon cycle, plants constantly remove carbon from the atmosphere through photosynthesis and emit carbon into the atmosphere through natural processes, including respiration and decay. In contrast, fossil fuels, such as coal, oil, and natural gas, take millions of years to form and cannot replenish themselves in this same way in short time periods.

When a wood bioenergy plant burns biomass to make electricity, it releases the carbon stored in the biomass into the atmosphere. Proponents of the carbon neutrality of forest biomass and bioenergy argue that the same carbon that was removed from the atmosphere by the tree’s growth is being released as the biomass burns. Because the carbon removed by the living tree is the same as the carbon released by burning the biomass from the tree, forest biomass and bioenergy is said to be “carbon neutral.”

What are the implications?  If, ultimately, the EPA decides that biomass energy is not inherently carbon-neutral, then biomass power could struggle to grow as an energy source. If biomass is not deemed carbon neutral, then perhaps one could question its renewability.  If biomass is no longer considered renewable and cannot be used to meet renewable portfolio standards, then few incentives exist for producers to generate biomass for power.  Regardless, further study of this, can, as a former professor of my Dad’s said, “titillate our lascivious desires creating a symbiosis of emotion.”  Or not.

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