It’s expensive to upgrade coal-burning power plants to control smokestack emissions of mercury and other pollutants. The new technology doesn’t reduce greenhouse gases.


Plant Owner Location Output* Startup Retrofit Cost Completion

Big Stone Otter Tail Power† Big Stone City, S.D. 475MW 1975 $405M 2015

Boswell 4 Minnesota Power† Cohasset, Minn. 585MW 1980 $431M 2015

Boswell 3 Minnesota Power Cohasset, Minn. 350MW 1973 $240M 2009

Genoa 3 Dairyland Power‡ Genoa, Wis. 379MW 1969 $136M 2015

Madgett Dairyland Power‡ Alma, Wis. 400MW 1979 $179M 2016

Sherco 1-2 Xcel Energy§ Becker, Minn. 1,500MW 1976-77 $45M 2014


* one megawatt (MW) equals 1 million watts. † majority owner and sole operator; Big Stone owned by three utilities; Boswell 4 owned by two utilities.

‡ La Crosse, Wis., cooperative supplies power to Minnesota municipal utilities and co-ops, including Great River Energy, which contracts for 50% of Genoa plant’s output.

§ No decision on other upgrades estimated to cost $340 million Source: Individual utilities