Oregon has been having a robust debate over the appropriate date for closing the state’s lone coal power plant. The Boardman plant could theoretically operate until 2040, but its owners have proposed an earlier closure to avoid investing in expensive pollution controls.

wind turbine poster-flickr-CERTsThere’s been a lot of discussion about whether the plant should close in 2015 or 2020 (and how much its owners must spend in the meantime.) But that disagreement has become so central to the discussion that it’s overshadowed what may be a much more important question: What happens after the coal plant closes?

Will Portland General Electric adopt another outdated fossil fuel strategy, building natural gas plants that will continue to release greenhouse gas emissions for decades to come? Or will the utility think creatively to pursue low-carbon options that reduce demand in the first place and then fill it with clean wind, solar or geothermal energy? If your chief concern is addressing Oregon’s largest single source of greenhouse gas emissions, the replacement strategy matters. While burning natural gas is less polluting than coal, that process can still release roughly half the carbon emissions. A significant amount. And if a utility invests millions of dollars to build a new gas plant, they’ll want to run it for a long time.

Here’s some rough math to illustrate the point that long-term thinking should matter most.

  • On average, Boardman releases roughly 4 million tons of CO2 each year. If the coal plant keeps running from 2015 to 2040, it would release 100 million tons of CO2 during that time period.
  • If you close the coal plant in 2015 and replace its power with a new natural gas plant that releases about half the pollution, you’d emit 50 million tons of CO2 over that same period. Sounds better!
  • But say you keep the coal plant running until 2020, at which point you replace the coal power with completely clean energy sources. In that scenario you’d emit just 20 million tons of CO2 over the period from 2015 to 2040.

I’m not suggesting that we shouldn’t try to move our region off of the dirtiest, most polluting power source as soon as possible. But I am suggesting that it’s equally—if not more—important to focus on what happens next. Saving 30 million tons of CO2 — the potential difference between replacing Boardman with a gas plant or clean renewables—would be like taking every car in the state of Oregon off the road. And leaving them parked for two years.

I bring this up now because a compromise agreement reached last week between Portland General Electric and a consortium of ratepayer and environmental advocates finally begins to address the replacement question. (Here’s coverage of the deal in The Oregonian and the Portland Tribune.)

  • The groups, which include the Oregon Environmental Council, the Citizens’ Utility Board, Renewable Northwest Project, and the NW Energy Coalition, have agreed to support a closure date no later than 2020 in exchange for some guarantees from PGE, including:

    • Looking for low-carbon and renewable replacement options
    • Taking the 2040 closure date off the table
    • Meeting Clean Air Act standards until the plant closes

    Not everyone will agree on the wisdom of endorsing a 2020 date, and some will continue to push for the coal plant to close sooner. But this agreement appears to give the parties a stronger voice in deciding how we replace Boardman’s electricity. And I’m glad to see people focusing on that piece of the puzzle, since those decisions will be with us for much longer.

    Update: The parties to the agreement outline the thinking that informed their decisions in today’s Oregonian.

    Wind turbine image courtesy of flickr user CERTs via a Creative Commons license.

    Note on methodology: Annual C02 emissions for Boardman come from the EPA Clean Air Markets Data and Maps. Based on operating data submitted to the Northwest Power Planning and Conservation Council, Boardman’s emissions rate in 2007 was 2,200 lbs of CO2 per megawatt hour. The emissions rate for a combined cycle natural gas plant is 1,100 lbs of CO2 per megawatt hour, based on states’ emissions performance standards.

    If Boardman continued burning coal at the same rate from 2015 to 2040, it would release about 100 million tons of CO2. (4 million tons per year for 25 years.) Shutting the coal plant down in 2015 and switching to a new natural gas plant would release 50 million tons of CO2 (2 million tons per year for 25 years.) Shutting the coal plant down in 2020 and switching to carbon-free sources of energy would release only 20 million tons of CO2 (4 million tons in each of the years between 2015 and 2020 but none after that.)

    The car comparison assumes that the 3.2 million passenger cars registered in the state of Oregon drive 10,000 miles per year and get 20 miles per gallon and that there are 19.6 pounds of CO2 in each gallon of gas.