Ethanol and Air Quality – Separating Fact from Fiction

Source: By Jessie Stolark, EESI • Posted: Monday, October 15, 2018

On October 9, President Trump announced that he was directing EPA to allow year-round sales of E15 (15 percent ethanol, 85 percent gasoline), and it is expected that the EPA will release a Notice of Proposed Rulemaking in the coming weeks to allow the sale of higher blends of ethanol.  After Tuesday’s announcement, the oil industry and some environmental groups were quick to claim that increasing the volume of ethanol in the fuel supply would worsen air quality. However, the evidence suggests otherwise.

An obscure piece of air quality regulation—Reid Vapor Pressure (RVP) standards—inadvertently blocks the year-round sale of E15, with the result that the fuel is able to be sold only 8 months of the year, causing many fuel retailers to consider the fuel more of a nuisance than a selling point for their stations, despite the lower price of E15 relative to other fuel offerings.

Currently, 1,400 stations in 29 states offer E15, but it’s thought that many more would offer the fuel if they could sell it year-round. Therefore, the ethanol industry and supporters in Congress have made allowing year-round sales of E15 a major focus, either through administrative action, or through a Congressionally-mandated waiver to the Clean Air Act, such as found in the Consumer and Retailer Fuel Choice Act (S.517, H.R. 1311).

When considering the air quality impacts of increasing the ethanol content of gasoline, both the evaporative emissions and tailpipe emissions must be considered. In general, the existing scientific literature supports the conclusion that increasing ethanol content from E10 to E15 reduces harmful volatile organic compound (VOC) emissions, displaces cancer-causing emissions, and reduces smog-forming potential, as well as cuts greenhouse gas emissions. Ethanol blends above E15 further dilute the presence of these harmful compounds in gasoline.

Additionally, newer research on “splash blending” (simply adding ethanol to finished gasoline) expected to be published later this year has found that increasing the volume of ethanol in the fuel supply to 30 percent (E30) has the greatest positive impact on tailpipe emissions of toxins out of any commercially available fuel. This included significant reductions in ultrafine particulates and carbon monoxide. Additionally, this newer research finds that E30 did not contribute to smog formation (a mixture of nitrous oxides and carbon monoxide).

While more research to validate these findings on ethanol’s positive impact to air quality will be useful, the news that E15 could be sold year round should be seen as a positive step for air quality.

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