Canadian Biomass Magazine

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Tool allows life-cycle carbon comparisons

May 12, 2012
By Scott Jamieson


May 12, 2012 - Finally there is an objective tool anyone can use to compare the full life-cycle of emissions for various renewable and non-renewable energy sources when it comes to electricity generation. No surprise, bioenergy does very well.

Based on over 2,000 independent and peer-reviewed studies, this simple online program allows users to choose their competing power sources, and then see graphs comparing the range of carbon emissions over the fuels' lifespan.

Produced by the the U.S. Department of Energy’s National Renewable Energy Laboratory, the tool is customizable by the user via simple toggle boxes, and allows comparison of coal, natural gas, nuclear, biomass, solar, wind, geothermal, hydro, ocean and more.

Dubbed the LCA Harmonization Project, the researchers systematically reviewed estimates of
life cycle GHG emissions from electricity generation technologies
published between 1970 and 2010. LCAs consider emissions from all stages
in the life cycle of an electricity generation technology, from
component manufacturing, to operation of the generation facility to its
decommissioning, and including acquisition, processing and transport of
any required fuels.

Lifespan emission are measured in grams of CO2 per kilowatt of electricity generated, and reported in ranges as well as medians. Recent claims aside, biomass emissions (median of 40 g/kWh) in general are vastly lower than coal (1,001) or natural gas (477). Other renewables also perform very well, with photo-voltaic (44) and geothermal (40) close to biomass, and wind (11) and hydro (7) leading the pack. Overall the tool makes a strong case for a more varied energy mix that includes a much higher share for renewables (and oddly enough, nuclear, at least as far as this one criteria goes).

Biomass sources in the studies include agricultural residues, mill
waste, harvest residues, woody crops, herbaceous crops, animal waste,
and urban waste. Technology options include co-firing, direct
combustion, and gasification.  Within the biomass category, mill and urban wastes not surprisingly have the lowest emissions, with forest residues and woody crops close behind. Animal wastes had the highest emissions, although all the biomass feedstocks are well below coal or natural gas emissions. For technology, direct combustion (35) and co-firing (48) are good options.

This application allows for customized visualization of summary
statistics and the underlying published estimates collected for each
technology, as well as companion harmonized estimates. Data selected and
their associated reference citations can be downloaded, making results more transparent.

To try out this tool yourself and see the data and studies behind it, click here.

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