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Biomass Among Best Options for Reducing GHG Emissions

A paper published in Environmental Science and Technology by researchers at the Goddard Institute for Space Studies & Columbia University Earth Institute and the National Renewable Energy Laboratory compared life cycle greenhouse gas (GHG) emissions of both fossil and renewable sources of electricity. Their purpose: to vet the options available for phasing out CO2 emissions from the use of coal in the United States. Their conclusions: “geothermal and biomass energy could displace much of the baseload electric power now provided by coal in the near term.”1

The paper, which I will refer to as the Kharecha paper (after its lead author), aggregates multiple life cycle greenhouse gas assessments covering all major electricity sources—both fossil and renewable—thereby allowing us to look at each source’s GHG impact in relation to the others. The following figure from the Kharecha study2,3 summarizes the results.(Click on image to enlarge; hit back button to return to post.)

Biomass makes the final list of reommendations in the paper because compared to other sources, it meets and exceeds several requirements. It is renewable. It is an on-demand source and therefore capable of supplying base load power. And as the above figure shows, electricity generated from tree plantation biomass has a GHG emission profile over its life-cycle that compares favorably to all fossil fuels and is similar to those of other renewables. It has additional benefits that no other source offers as well. According to Kharecha, biomass is unlike other renewable sources because it incorporates carbon capture and storage (CCS): “biomass power, properly designed to account for full life-cycle impacts, has special attraction because, combined with CSS, it has the potential to draw down atmospheric CO2.”

1 Pushkar A. Karecha, Charles F. Kutscher, James E. Hansen, and Edward Mazria, “Options for Near-Term Phaseout of CO2 Emissions from Coal Use in the United States,” Environmental Science and Technology 2010, Volume 44, pages 4050-4062. Copyright 2010. American Chemical Society. Available at the ACS website.

2 Figure reprinted with permission from: Pushkar A. Karecha, Charles F. Kutscher, James E. Hansen, and Edward Mazria, “Options for Near-Term Phaseout of CO2 Emissions from Coal Use in the United States,” Environmental Science and Technology 2010, Volume 44, pages 4050-4062. Copyright 2010. American Chemical Society. Available at the ACS website.

3“Life-cycle GHG emissions from fossil and alternative sources of electricity. Values based on refs 18-20, 47, 59, and 92-96. Error bar for natural gas denotes liquified natural gas plants (95); emissions from plants using syngas (produced from coal gasification) can range from about 950-2300 tCO2-eq/GWh (95). Error bar on CSP denotes hybrid plants employing cofiring with natural gas (47). High-end geothermal value denotes an approximately global average for lithospheric CO2 emissions from direct steam and flash steam plants (19). Improperly designed biomass-based approaches could result in much higher emissions than shown here (34, 35).”


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