* To stop burning coal at some plants by 2016
* May convert in some cases to natural gas
* Sierra Club threatened suit last July
Jan 22 (Reuters) - Utility company MidAmerican Energy Co said it has reached a settlement with the Sierra Club over power plant emissions, which includes a pledge to stop burning coal at certain plants over the next few years.
MidAmerican, a unit of Warren Buffett's Berkshire Hathaway , said in a statement on Tuesday the deal was in response to a July 2012 notice from the environmental group. The Sierra Club said at the time it intended to sue over purported violations of the Clean Air Act.
Under a consent decree filed with a federal court in Iowa, the utility said it would stop burning coal by mid-April 2016 at Neal Energy Center Boilers 1 and 2 and at the Walter Scott Jr. Energy Center Boilers 1 and 2.
Those units produced just over 536 megawatts of electricity, the utility said, adding that it would consider keeping them open with the use of other fuels.
MidAmerican also said it would also stop burning coal at the 137.4-megawatt Riverside Generating Station and would convert it to natural gas instead.
"MidAmerican Energy has been and remains in compliance with the law," the company said, adding that Iowa authorities had not pursued any enforcement actions against any of its plants.
"MidAmerican Energy entered into settlement discussions as a means to avoid costs to its customers, unnecessary delays, and ongoing uncertainty associated with litigation," it said.
The utility serves more than 700,000 customers in Iowa, Illinois, Nebraska and South Dakota.
The Sierra Club said the settlement would improve air quality in Iowa but was only one step in its broader effort to reduce coal emissions.
"Today's settlement marks an important national milestone to end the scourge of coal, as well as an important milestone in our ongoing discussion with the Warren Buffett family of companies about combating climate disruption," said Bruce Nilles, senior director of the Sierra Club's "Beyond Coal" campaign, in a statement.
Niles said the campaign, which wants to eliminate coal burning in the United States by 2030, intends to push Buffett's utility Pacificorp and his railroad BNSF to end their coal-burning and -hauling operations as well.