The U.S. Supreme Court issued a ruling on Monday, June 23, 2014, which upheld the authority of EPA to regulate carbon dioxide under the Clean Air Act (CAA), but with limitations. The Court held that EPA may require permits and carbon control efforts for large stationary sources that emit large quantities of carbon dioxide. The emission of certain quantities of other regulated greenhouse gas (GHG) emissions -- not carbon dioxide alone -- must trigger the requirements, however. The Court held that EPA went impermissibly beyond its authority to regulate carbon dioxide under the CAA when, under its "Tailoring Rule," the Agency raised the triggering thresholds for carbon dioxide regulation.

The biomass community has been weighing in on EPA efforts to determine how to account for bioenergy emissions under its Tailoring Rule. Despite this week's Supreme Court ruling, there are ongoing efforts to urge EPA to issue in final its biogenic carbon accounting framework for those bioenergy facilities that would trigger permitting and other carbon control requirements based on the levels of emission of regulated GHG emissions other than carbon dioxide.