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Climate Change, Energy

Emissions and costs of electricity from coal, natural gas, wood pellets

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Biomass — wood chips, tree parts and agricultural waste burned to generate heat and electricity — currently generates more 50% of the United States’ renewable energy production.  Because biomass is carbon neutral, it has significant advantages over fossil fuels.

Based on a case study on two coal-powered stations in Ontario, Canada, a 2009 published in Environmental Science and Technology, “Life Cycle Emissions and Cost of Producing Electricity from Coal, Natural Gas and Wood Pellets in Ontario, Canada,” looks at the potential advantages for electricity-generating companies of substituting biomass fuels for coal.

This research shows that biomass can be a cost-effective method for reducing greenhouse gas emissions. Its findings include:

  • The maximum greenhouse gas emission reduction is achieved when coal is totally replaced with wood pellets.  Emissions reduction would amount to 91% relative to using coal and 78% relative to using natural gas combined cycle (NGCC) facility.
  • The most cost-effective greenhouse gas mitigation method is either by co-firing with coal or using natural gas combined cycle (NGCC).
  • If all coal-generating stations in the United States and Canada burned 90% coal and 10% biomass, the countries’ greenhouse gas emissions would fall by about 170 million metric tons per year, accounting for about 5% emissions reduction from the countries’ electricity sectors.
  • Estimates of the cost of retrofitting a coal-fired facility to burn biomass range from $125 to $1,500 per kilowatt of capacity; a recent retrofit was completed  at a cost of $640 per kilowatt of capacity.

In conclusion, the authors write: “With biomass, as with any resource, large-scale implementation must be done cautiously. Benefits will be achieved only if policies are enacted that steer biofuels in the ‘right direction’ and if environmentally sustainable practices are employed throughout the [life cycle].”

Tags: coal, fossil fuels, carbon, greenhouse gases

    Writer: | Last updated: February 10, 2010

    Citation: Zhang, Yimin; et al, "Life Cycle Emissions and Cost of Producing Electricity from Coal, Natural Gas, and Wood Pellets in Ontario, Canada," Environmental Science & Technology, January, 2010, 44 (1), 538–544. DOI: 10.1021/es902555a

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    Analysis assignments

    Read the study titled "Life Cycle Emissions and Cost of Producing Electricity from Coal, Natural Gas and Wood Pellets in Ontario, Canada."

    1. Summarize the study in fewer than 40 words.
    2. Express the study's key term(s) in language a lay audience can understand.
    3. Evaluate the study's limitations. (For example: Do the results conflict with those of other reliable studies? Are there weaknesses in the study's data or research design?)

    Read the issue-related New York Times article titled "President Touts His Alternative Fuels Plan."

    1. If you were to rewrite the article based on knowledge of the study, what key changes would you make?

    Newswriting assignments

    1. Write a lead (or headline or nut graph) based on the study.
    2. Spend 60 minutes exploring the issue by accessing sources of information other than the study. Write a lead (or headline or nut graph) based on the study but informed by the new information. Does the new information significantly change what one would write based on the study alone?
    3. Interview two sources with a stake in or knowledge of the issue. Be prepared to provide them with a short summary of the study in order to get their response to it. Write a 400-word article about the study incorporating material from the interviews.
    4. Spend additional time exploring the issue and then write a 1,200-word background article, focusing on major aspects of the issue.