The utility intends to install activated carbon injection and/or dry sorbent injection technology on its St. Clair, Belle River, River Rouge and Trenton plants to reduce mercury emissions. DTE has spent about $2 billion on pollution controls in recent years at it’s largest baseload coal plant, the 3,000-megawatt Monroe generating station on the western shore of Lake Erie, enabling Monroe to meet the MATS rule that took effect in mid-April.

Monroe’s four units went into commercial operation between 1971 and 1974. The plant is the largest electric generator in Michigan and one of the largest in the Midwest. It burns nearly 10 million tons of low-sulfur Powder River Basin coal annually.

To help pay for the new environmental spending, DTE self-implemented more than half of a $370 million annual electric rate increase still pending before the Michigan Public Service Commission (PSC). Under a 2008 Michigan law, utilities are permitted to self-implement rate hikes, subject to possible refund, if the commission has not acted within six months on a new rate request. The company filed its latest rate case in December 2014. A final PSC order is expected by the end of this year.

DTE is getting strong pushback from environmental groups such as the Sierra Club and Michigan Environmental Council for the new pollution controls at St. Clair, Belle River, River Rouge and Trenton, which together total more than 3,000 MW of generating capacity.