U.S. EPA has proposed new standards for greenhouse gas (GHG) emissions from new power plants. See here (press release) and here (for more, including links to the proposed standard). According to Bloomberg: "The rules will permit emissions from new power plants at 1,000 pounds of carbon dioxide per megawatt hour, about the level for a modern natural-gas plant, the EPA said today in an e-mailed statement. The limit would effectively preclude construction of new coal-fired plants, which are struggling to compete with decade-low natural gas prices." For more, see here.
