Ethanol Blends Adding to State’s Air Pollution

By Published On: January 22, 2007

As California increases its production and consumption of ethanol as a transportation fuel, smog is worsening in the short run. However, state air-quality regulators say that the increase in unhealthful smog-forming emissions from ethanol will decline over time as new cars and gas station pumps replace older models. “SCAQMD does have concerns about increased emissions from low-level blends of E85 due to permeability,” said Sam Atwood, South Coast Air Quality Management District spokesperson. While increased use of alternative fuels in the name of energy security and reducing greenhouse gas emissions is becoming a state policy goal, the air district thinks that introduction of ethanol into the state’s gasoline as an additive has increased summer ozone levels since the additive methyl tertiary-butyl ether, commonly known as MTBE, was banned in 2004. The state nixed MTBE as an additive because it easily contaminated drinking water. Additives are used to help motor fuel burn more completely and thereby minimize carbon monoxide emissions. The recent summer ozone spike, the district believes, is due to increased hydrocarbon emissions that result when ethanol is mixed with gasoline. After years of declining summer ozone levels, the lung-burning pollutant started to increase in 2003. Studies show that ethanol at low levels increases a process called permeation, in which fuel gradually seeps into the air through rubber fittings and other seals in automotive fuel supply systems. “It’s probably a real concern in the short term,” said Jerry Martin, spokesperson for the California Air Resources Board. However, he said that new cars and gas pumps are designed to prevent increased permeation from occurring when ethanol is blended at low levels into gasoline. So as the automotive fleet “turns over,” emissions from permeation will decrease, Martin explained. Air board data show that it can take as long as 12 to 15 years for half of the state’s passenger car fleet to turn over, though old cars tend to be driven less. Meanwhile, use of ethanol will climb. Currently, California gasoline contains about 6 percent ethanol. That amount is expected to grow to up to 10 percent as new production plants open and as the state seeks to reduce greenhouse gas emissions from transportation fuel. CARB regulations allow blends of up to 10 percent ethanol. If the heightened emissions continue, it will make it more difficult for the region to meet federal health standards for ozone, a respiratory irritant, and fine particulate, which causes a variety of respiratory and heart ailments associated with premature death, according to a paper by Joe Cassmassi, SCAQMD planning and rules manager. Studies by the California Air Resources Board show that smog-forming hydrocarbon emissions may increase by 118 tons on hot summer days statewide because of increased permeation with ethanol in fuel. In the South Coast Air Basin, ethanol-driven permeation increases hydrocarbon emissions by 42 tons per day during summer – more than 4 percent. Total hydrocarbon emissions in the region, which includes smoggy Los Angeles, are 975 tons/day. Emissions of toxic pollutants, including cancer-causing benzene, from vehicles also increase under some weather conditions, the study found. Increasing ethanol use is creating another air pollution problem too, one that has yet to be solved. That is, low-level blends of ethanol also create a “nitrogen oxide penalty,” explained Martin. Emissions studies of ethanol show that it increases nitrogen oxide emissions statewide by as much as 21 tons/day and in the Los Angeles area by 8 tons/day, or less than 1 percent. Total nitrogen oxide emissions in greater Los Angeles are 1,104 tons/day. ” We prefer E85,” said Martin, a fuel that contains 85 percent ethanol and 15 percent gasoline. E85 eliminates increases of emissions of both nitrogen oxides and hydrocarbons, he explained. California has about 260,000 flexible-fuel vehicles that can burn E85, but because of a lack of E85 pumps, they burn gasoline right now, Martin explained. Until more flex-fuel vehicles are sold, it will be difficult for fuel suppliers to justify opening E85 pumps because the cars are so widely dispersed, representing only about 1 percent of California’s 26 million cars. Automakers have pledged to make more of the cars by 2012 (Circuit, Jan. 12, 2007). Meanwhile, extra emissions from ethanol will work against the state’s efforts to reduce unhealthful levels of ozone and fine particulate pollution.

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