Rocky Mountain Power is proposing a unique strategy to lower emissions at the coal-fired Jim Bridger power plant near Rock Springs: reduce its capacity. The utility is required under federal law and within Wyoming's state implementation plan to reduce certain emissions before 2022. Enacted in 1999, the regional haze rule, is meant to limit pollutants that disrupt visibility like nitrogen oxide and sulfur dioxide.
Rocky Mountain Power has been planning to install selective catalytic reduction (SCR) technology by the end of 2021, which would convert toxic emissions into harmless ones. In February, the utility submitted a reassessment after finding a significantly cheaper strategy to reach the same result.
Dave Eskelsen, a spokesman for Rocky Mountain Power, said SCR technology would have cost hundreds of millions of dollars and that would have to be passed onto ratepayers.
"Our reasoning is that if you can do something else [like] operational constraints-basically emission limits-on all four units and achieve the same progress or better progress in this case to regional haze visibility at a much lower cost, that's a preferred option," Eskelsen explained.
He said lowering generation capacity would not only reduce cost, but would more comprehensively reduce environmental impacts. The utility submitted its application to the state Department of Environmental Quality back in February. In its letter to the Air Quality Division administrator, Nancy Vehr, Pacificorp's Director of Environmental Services James Owen explains the benefits.
"The Regional Haze Reassessment that PacifiCorp has completed and is proposing as part of this application is more cost effective, results in less overall environmental impacts, and leads to better modeled visibility than SCR installation on Units 1 and 2," Owen writes.
Rocky Mountain Power's parent company has found several Wyoming coal plants are more expensive to run than alternatives and could be in for early retirement. Jim Bridger was one of them. Eskelsen said the plan to lower capacity isn't connected to that analysis, but that it does come down to the same issue: cost.
"It does play into a factor. I mean, one of our reasons for proposing this reassessment on regional haze compliance is because installation of selective catalytic reduction is so expensive," Eskelsen said.
The Department of Environmental Quality is still considering the utility's application and does not have a timeline for a response.