Reuters: U.S. environmental regulators said on Tuesday the climate and energy bill in the Senate would only add slightly to average household costs, but the finding was not expected to boost chances for the legislation that would cap greenhouse gas emissions. The climate bill unveiled last month by Senators John Kerry, a Democrat, and Joseph Lieberman, an independent, would cost households an average of $79 to $146 per year through 2050, the Environmental Protection Agency said in an economic …