Two plants are cleaner than one
Several people have asked me why the Big Stone II participants selected the Big Stone site for the new plant. Why not somewhere in the North Dakota coal fields?
The short answer is we selected the Big Stone site because it has good rail access for coal deliveries; we can use common coal handling facilities; the location is strategic for regional transmission stability; and we have a plentiful water supply and pumping capacity for both plants.
Those are all very compelling reasons. And they will allow the Big Stone II participants to build and operate a plant at costs lower than other locations. But, cost saving isn't the only plus . . . our choice will be good for the environment as well. Here's why.
The addition of Big Stone II will more than double the amount of power produced at the Big Stone site. However, the amount of emissions will not increase at all. In fact, the two plants combined will emit the same amount or less sulfur dioxide (SO2), nitrogen oxides (NOX) and mercury than the existing Big Stone plant.
How is that possible? We have selected a single, highly advanced wet scrubber to serve both plants, which will reduce SO2 emissions from both plants to approximately one-seventh of the current levels from Big Stone I.
A combination of low NOX burners and selective catalytic reduction will provide superior control of NOX emissions, plus changes on Unit 1 which will allow the combined emissions to be equal to or a little less than 2004 levels.
A fabric filter baghouse will provide superior particulate (ash) emission control and will also help remove mercury. And, speaking of mercury, the Big Stone II project will allow us to cap mercury emissions at 189 pounds per year - equal to the level reported in 2004 by Big Stone I alone.
We've planned well to control carbon emissions too. The new plant will use a supercritical pulverized coal boiler. This technology will allow us to produce electricity using 20 percent less fuel than a comparable coal-fired plant using traditional boiler technology.
Selecting the current Big Stone site for the new plant was the result of thoughtful consideration for both cost and environmental stewardship. We believe Big Stone II meets both those objectives.
Mark Rolfes
Big Stone II Project Manager
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