Even after shutdowns, coal power still a mainstay in Minnesota

  • Article by: DAVID SHAFFER , Star Tribune
  • Updated: February 10, 2013 - 1:48 PM

Despite the pending retirements of smaller power plants, coal will remain a key source of Minnesota’s electricity — and of greenhouse gas emissions.

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Xcel’s coal-fired Sherco generating station in Becker is the state’s largest emitter of greenhouse gas. Xcel is studying whether to keep two 1970s-era units there.

Photo: Glen Stubbe, Star Tribune

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The end of coal burning is coming to a dozen Minnesota electric generators. But it will hardly put a dent in the state’s greenhouse gas emissions, a Star Tribune analysis shows.

Over the past year, utilities in Minnesota have announced that 12 coal burners are being retired or switched to burn ­natural gas, mostly by 2016.

They are small, older units, some of them little used and uneconomical, and account for just 3 percent of the state’s emissions of carbon dioxide, a gas linked to global warming.

“It’s not going to be the silver bullet for addressing greenhouse gas emissions,” said David Thornton, an assistant commissioner for air policy and pollution for the Minnesota Pollution Control Agency.

Electricity generation contributes nearly a third of the state’s greenhouse gases because many power plants rely on fossil fuels, mainly coal and increasingly natural gas.

When the smaller coal plants from Hoyt Lakes to Burnsville to Rochester are gone, Minnesota electric customers still will be getting a major share of their power from a fleet of larger, newer coal plants that utilities plan to keep operating.

The remaining 12 coal generators spew nearly six times more carbon dioxide than the small units slated to go away — about 17 percent of the state’s overall greenhouse gas emissions, according to the newspaper’s analysis of state smokestack data.

Utilities across the Midwest are considering pollution-control investments to extend the life of their big coal plants.

More than 100 of them on the Midwestern power grid are planning such upgrades, according to a fourth-quarter survey by the grid operator MISO. While fewer coal plants will remain, they will be 50 percent bigger on average than those of today, the survey ­suggests.

Upgrading them would cut some smokestack emissions — reducing smog, mercury and haze — but it would have little effect on carbon dioxide, the main greenhouse gas they emit. Experts say that no economically proven technology exists to remove greenhouse gases from smokestacks.

These potential investments in coal power plants come at a time when political leaders from President Obama to Gov. Mark Dayton have advocated more action on climate change. Obama mentioned it in his inaugural address last month, leading to speculation that he will offer details Tuesday in his State of the Union address.

The U.S. Environmental Protection Agency last year proposed greenhouse gas regulations for new power plants that make it unlikely more will be built. The EPA has not proposed rules for existing power plants, although many experts, including the MPCA’s Thornton, believe they are coming.

“Within a few years we are going to see a limit on the carbon pollution from those plants,” said J. Drake Hamilton, science policy director for Fresh Energy, a St. Paul-based nonprofit that supports renewable energy. “It is not a static situation. The climate science has been clear for many years. Wise utilities are listening.”

Strategy: Diversify sources

The strategy of many utilities in Minnesota and elsewhere has been to retain some coal plants and diversify with wind power, solar and natural gas-fired generators, which emit less carbon dioxide, while promoting conservation by customers.

“If you look nationally, Minnesota is probably one of the top states in the nation as far as leading the country in change,” said Al Rudeck, vice president of strategy and planning for Minnesota Power, the Duluth-based power company serving the Iron Range and central Minnesota.

Minnesota Power, which long relied almost exclusively on coal generation, last month announced it would shutter one coal burner and convert two others to burn natural gas, and add wind power, hydro and probably a new natural gas-fired generator. Its aim eventually is to get a third of its energy from coal, a third from natural gas and a third from renewable sources.

  • Top five GHG emitters in Minnesota 2011

    Four coal-burning power plants and a major oil refinery are the largest sources of greenhouse gases in the state.

    Facility City GHG in tons

    Xcel Energy Sherco Power Plant Becker 13.1M

    Minnesota Power Boswell Energy Center Cohasset 7.5M

    Flint Hills Resources Pine Bend Refinery Rosemount 3.6M

    Xcel Energy Allen S. King Power Plant Oak Park 3.3M

    Heights

    Xcel Energy Black Dog Power Plant Burnsville 1.5M

    Source: EPA

    greenhouse gas sources in Minnesota

    Electric power and transportation account for most of the greenhouse gas emissions in Minnesota.

    (2010 data)

    Sector Percent

    Electric utility 32%

    Transportation 24%

    Agriculture 19%

    Industrial 13%

    Residential 7%

    Commercial 4%

    Waste/landfill 1%

    Source: Report to Minnesota Legislature

    Minnesota electricity sources

    Fuel Percent

    Coal 53%

    Nuclear 22%

    Wind 13%

    Natural gas 6%

    Biomass, wood 3%

    Hydroelectric 1%

    Other 1%

    Note: does not equal 100% due to rounding.

    Source: U.S. Energy Department, 2011 data.

    Coal power and GHGs

    Twelve of Minnesota’s 24 coal-fired electical generating units will stop burning coal, in most cases by 2016. The remaining 12 coal burners are larger generators responsible for a greater share of the coal-power sector’s emissions of greenhouse gases (GHG), 2010 state data show.

    Average Average GHGs* Share�

    Age megawatts� emitted

    (in years) (in tons)

    All coal plants 49 209 31.4M

    12 ending coal 54 59 4.7M 15%

    12 remaining coal 45 359 26.6M 85%

    * carbon dioxide, methane and nitrous oxide.

    � share of GHGs among 24 coal power plants only.

    �1 megawatt equals 1 million watts.

    Source: Data from Minnesota Pollution Control Agency, U.S. Environmental Protection Agency, analysis by Star Tribune.

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