Sunday, June 13, 2010

Forest Carbon Sequestration Is Not Recommended Yet: A Massachuestts study

A lifecycle study of woody biomass smashes another blow to biomass energy proponents.
The study, prepared for Massachusetts' Department of Energy Resources, found biomass energy from forest management cannot reduce greenhouse gas emissions compared to continued fossil fuel energy consumption.

For the report, authors introduce a concept called 'carbon debt' of biomass energy. Before the carbon sequestration occurs by forest re-growth, forest biomass emits more greenhouse gases than fossil fuels per unit of energy produced. This carbon debt will be paid off by the re-growth over time. The following table shows how long it will take for forest biomass to pay off its carbon debt to its replaced fossil fuel energy.
Fossil Fuel Technology Replaced
 Carbon Debt Payoff (yr)
Oil (#6), Thermal/CHP
Coal, Electric
Gas, Thermal
Gas, Electric

This information is very disappointing to many policy makers, most of whom set target years in 2030 or 2050. In terms of net carbon sequestration, forest biomass cannot reduce greenhouse gas emissions by 2050. Forest biomass cannot compete with natural gas electricity until 2100.
Biomass Cumulative % Reduction in Carbon Emissions (Net of Forest Carbon Sequestration)
Oil (#6) Thermal/CHP
Coal, Electric
Gas, Thermal
Gas, Electric

Source: Walker, T., Cardellichio, P., Colnes, A., Gunn, J., Kittler, B., Perschel, B., Recchia, C., & Saah, D. (2010). Biomass Sustainability and Carbon Policy Study. Brunswick, ME: Manomet Center for Conservation Sciences. [Full-text at]

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