Yesterday’s Supreme Court decision confirming the Environmental Protection Agency (EPA) has the authority to regulate carbon dioxide emissions in motor vehicles makes it more likely the agency will set CO2 emission standards on engines to fulfill a Congressional mandate of the Clean Air Act.
The decision will have greater impact on gasoline engines, and by extension cars and light trucks, than diesel engines. This is because diesel engines emit between 10 and 20% less carbon dioxide than an equivalent gasoline counterpart, according to Dawn Fenton, manager of policy and technical programs for the Diesel Technology Forum advocacy group.
However, the Clean Air Act also gives EPA the flexibility to target stationary greenhouse gas emitters, such as power plants and manufacturing facilities.
The Court ruling has no impact on the 2007 and 2010 diesel engine emission standards EPA currently has in place. These standards reflect EPA’s aggressive policy to reign in emissions of particulate matter (PM) and nitrogen oxide (NOx)— not carbon dioxide— from diesel engines.
The trucking industry is currently undergoing a significant environmental transition as all on-highway diesel engines built in 2007 must meet more stringent PM and NOx emissions requirements. That requirement last year led refiners to switch nearly all on-highway diesel to an ultra-low sulfur blend. OEMs this year began installing costly diesel particulate filters on all vehicles with ’07 engines.
“For the first time the Supreme Court said EPA has authority to regulate CO2 emissions,” Fenton told FleetOwner. “But the 2007 and 2010 regs…[are] for PM and NOx emissions; there’s no direct relationship between that and EPA’s authority [on greenhouse gases].”
However, the Court decision will likely shape a pending lawsuit that calls into question the State of California’s authority to regulate greenhouse gases, a challenge brought fourth by automotive industry interests.
“This brings up the question, what is EPA going to do about regulating emissions and how does that factor into CARB’s (California Air Resources Board) ability to regulate CO2 emissions,” Fenton said.
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