American Electric Power, one of the country’s largest coal-burning utilities, said on Thursday it plans to retire nearly one-quarter of its coal fleet and retrofit other units at a cost of as much as $8 billion to comply with proposed environmental regulations. To meet stricter pollution limits for air, water and coal waste, AEP said it will retire 6,000 megawatts of coal-fired generation in Virginia, West Virginia and Ohio in 2014. It also plans to upgrade or install new advanced emissions reduction equipment on another 10,100 MW, convert 1,070 MW of coal generation to 932 MW of natural gas capacity and build 1,220 MW of natural gas-fueled generation. The Columbus, Ohio-based company, which operates utilities in 11 states serving 5 million customers, warned that costs of the proposed regulations to customers and local economies have “been vastly underestimated,” especially in Midwestern states that rely heavily on coal to produce electricity.

Exxon Mobil Corp will pay $25 million as part of a settlement to clean up a decades-old oil release in New York City, the state’s attorney general said on Wednesday. The settlement, filed in U.S. district court in Brooklyn, requires Exxon to conduct a comprehensive cleanup of its Greenpoint facility in Brooklyn, which includes oil floating on top of the water table and contaminated groundwater and soil. “For far too long, residents of Greenpoint have been forced to live with an environmental nightmare lurking just beneath their homes, their businesses and their community,” Attorney General Andrew Cuomo said in a statement.

Efforts to permanently plug the world’s largest offshore oil spill reached a milestone when BP Plc’s crucial relief well reached its target — the blown-out Macondo well that began spewing oil almost five months ago, a U.S. official said. Now that the relief well has intersected with BP’s well, workers have an opening through which they can pump in mud and cement to kill the Macondo well for good. “The aggregate data available supports the conclusion that the two wells are joined,” retired Coast Guard Admiral Thad Allen, the top U.S. official overseeing the spill response in the Gulf of Mexico, announced late Thursday in a statement.