Large facilities with smokestacks, such as factories and electricity-generating units, must apply for and comply with air pollution permits issued by the MPCA. Permitted facilities still make up 21% of the total emissions in the state, but they have achieved significant reductions in the past 20 years. The Clean Air Act brought about these major emissions reductions by requiring process changes, new equipment, and pollution control devices.
Emissions trends for permitted facilities 2007-2016
Major emissions reductions from power plants
State statutes and rules, along with national standards for mercury and air toxics emissions from coal-fired utility boilers, have resulted in significant reductions in emissions of mercury and other pollutants in Minnesota. In 2006, Minnesota passed the Mercury Emissions Reduction Act (MERA), which set a schedule for the largest coal-fired utility boilers in the state to reduce mercury emissions by 90% from 2005 levels. As of 2015, all Minnesota utilities have achieved full compliance with MERA. To get there, they retrofitted some coal plants with improved pollution controls, switched some to natural gas, and shut down others. The changes these facilities made to reduce mercury emissions also brought 75-80% reductions in emissions of haze-forming pollutants as well as significant reductions in greenhouse gases. Utilities continue to shut down coal plants in Minnesota as they rely more on renewable energy and natural gas. Several of the remaining coal plants in Minnesota will close in the 2020s.
Reducing mercury pollution from coal-fired electric plants in Minnesota
Emissions reductions achieved through retrofitting and shutting down coal plants in Minnesota since the enactment of MERA. Some facilities that show reductions in earlier years appear again in the 2020s because they were first retrofitted to reduce emissions and will now be shut down.