An environmental group has served notice that it intends to sue northeastern Minnesota's biggest utility company, alleging violations of air pollution standards.
The Sierra Club maintains Minnesota Power has violated clean air standards more than 12,000 times over the last five years at its three coal-burning power plants, the Associated Press reports.
The Sierra Club's claims are based on opacity, which measures the thickness of emissions from a smoke stack by how much light passes through it, the AP says. Minnesota Power disputes the contentions in the Sierra Club's intent-to-sue notice. Officials with the utility tell the AP opacity can be caused by factors other than pollutants, citing water vapor as an example.
Northland's News Center reports the Sierra Club says data from 2012 suggest Minnesota Power's plants in Boswell, Taconite Harbor, and Laskin contribute to more than 300 asthma attacks and three dozen heart attacks per year.
The intent-to-sue filing triggers a 60-day notice period during which the two sides can try to come to a resolution, Northland's News Center says. A Sierra Club representative tells the station she hopes Minnesota Power puts its coal plants on a path to cleaner energy.
The company, though, says it has already done so. A Minnesota Power executive cites the utility's Energy Forward plan. Last year the company says it generated 80 percent of the power it sold by burning coal. Under the Energy Forward plan coal, natural gas, and renewable sources would each comprise one-third of the utility's power.
The Sierra Club has also been calling for Xcel Energy to stop burning coal at its Sherco plant near Becker. In December the Public Utilities Commission ordered Xcel to study retiring the two oldest units at that plant.
The burning of coal has been tied to greenhouse gases that scientists say contribute to climate change.