OREANDA-NEWS. President Barack Obama has vetoed a pair of congressional resolutions to overturn CO2 emissions regulations for power plants.

The resolutions the president vetoed would have nullified the US Environmental Protection Agency's (EPA) Clean Power Plan for existing power plants and its CO2 emissions limits for new generating units, the White House said on 19 December.

"The Clean Power Plan is essential in addressing the largest source of greenhouse gas pollution in our country. It is past time to act to mitigate climate impacts on American communities," Obama said in a memorandum dated 18 December that accompanied his veto of SJ Res 24, which would have overturned the existing unit standards.

Obama used what is known as a pocket veto to prevent the resolutions from taking effect. A pocket veto is when a president declines to take action on a bill after Congress adjourns. Such vetoes cannot be overridden. Congress adjourned for the year on 18 December. The president also took the unusual step of returning SJ Res 24 and its companion, SJ Res 23, which would have overturned the new-unit emissions limits, to Congress without his signature in order "to leave no doubt" they are being vetoed, the White House said.

The vetoes effectively mean any hopes that opponents have of overturning the regulations lay with litigation that has been filed in the DC Circuit Court of Appeals. The fiscal year 2016 budget deal Congress approved last week, and which Obama signed into law, did not contain language to restrict the ability of EPA to implement the rules in the coming year. The initial state implementation plans for meeting the Clean Power plan are due to EPA by early September 2016, just before the end of the fiscal year.

The House voted 242-180 and 235-188 to approve the two resolutions on 1 December, about two weeks after the Senate approved them by identical votes of 52-46. The votes were all well short of the two-thirds majority needed in each chamber to override a conventional veto of the resolutions.

The Clean Power Plan requires each state's power sector to meet a CO2 target by 2030, with interim goals for 2022-2029. EPA is encouraging the use of emissions trading to meet the targets, but says states can use a wide range of other measures, including energy efficiency and building more renewable energy generation. The new-unit limits require new coal-fired power plants to emit no more than 1,400lb CO2/MWh.