Proposed Iowa DNR plan would reduce nearly 10,000 tons of MidAmerican emissions

A proposed Iowa Department of Natural Resources revision would require MidAmerican Energy to improve equipment at select coal-fired power plants by the end of this year, which would reduce about 9,700 tons of sulfur-dioxide emissions per year and help prevent haze in natural areas.

Haze is when air pollutants absorb or scatter sunlight and obstruct visibility. Air pollutants can come from sources like power plants using fossil fuels, car exhausts and wildfires. In the Midwest, haze is primarily made from particles of sulfates, nitrates, organic carbon, soot and materials from the Earth’s crust.

The federal regional haze rule was announced in 1999 under the Clean Air Act to eliminate human-made visibility impairments in 156 national parks and wilderness areas by 2064. States are required to submit 10-year plans for restoring natural visibility conditions, along with progress reports every five years.

Iowa doesn’t contain any areas that are protected under this rule, nor is it within 186 miles of any such areas. However, based on data modeling, emissions from the state could comprise between 3 percent and 4 percent of human-made haze plaguing protected areas in Michigan, Minnesota and Missouri.

That’s why the Iowa DNR’s proposed revision to the state’s regional haze plan — now in its second 10-year period spanning 2019-28 — targets two MidAmerican coal-fired power plants: the Louisa Generating Station in Muscatine and the Walter Scott Jr. Energy Center in Council Bluffs.

The revision dictates more control of sulfur-dioxide (SO2) emissions by improving dry scrubber technology at the coal-fired power plants. Dry scrubbers are systems that can remove dangerous gases from emissions.

Since they already exist at the plants, dry scrubbers were deemed the most cost-effective option — totaling a combined $2.3 million in annual operating costs in 2019 dollars for both plants. The addition of new systems that would reduce SO2 and nitrate emissions were deemed too costly — surpassing $83 million and $56 million, respectively —and therefore unreasonable at this time.

The improvements are estimated to reduce about 3,900 tons of SO2 emissions each year from the Louisa Generating Station, which emitted 4,892 tons in 2022. About 5,800 tons per year will be reduced from a unit of the Walter Scott Jr. Energy Center, which emitted 7,236 tons in 2021.

MidAmerican fully supports the Iowa DNR’s revision, said company spokesperson Geoff Greenwood in an email.

“One of MidAmerican's core principles is environmental respect and we're fully committed to operating our facilities in a manner that meets or exceeds all regulatory requirements,” he said. “At this stage we don't intend to file formal comments regarding the draft documents, but we continue to be engaged with the DNR and other stakeholders in this process.”

If the draft is approved, operations and maintenance costs — such as those to operate emissions control equipment — would be allocated to customers following a rate case determination in front of the Iowa Utilities Board.

“MidAmerican has no plans to seek an electric rate case here in Iowa for the foreseeable future – for context, it would be at least years away,” Greenwood said. “We manage our operating and maintenance costs on behalf of our customers to keep energy bills affordable.” He added that MidAmerican’s electric rates in Iowa are currently eighth lowest in the nation.

Thus far, analyses have shown that no other sources in Iowa contribute to the majority of the sulfate and nitrate impacts in the 156 protected areas.

The Iowa DNR’s proposed draft of its regional haze plan opened for public comment Monday and will close on March 16.

Brittney J. Miller is the Energy & Environment Reporter for The Gazette and a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: (319) 398-8370; brittney.miller@thegazette.com