Ethanol and Smog
Ironically, this meant that the ethanol that was meant to be a cleaner gasoline alternative would actually lead to higher emissions from evaporation, and hence to greater smog formation. The flip side is that certain tailpipe emissions are lower when ethanol blends are used, and that helps offset the higher emissions from evaporation.
The potential for higher smog levels is behind the EPA’s concerns about allowing year-round sales of 15% ethanol blends (E15) nationwide. The ethanol industry would love to allow consumers across the country to buy E15 year-round, because it would increase their potential U.S. market by 50%.
President Trump has advocated for such a move. But there is debate over whether this change can be enacted by the EPA, or whether it will require new legislation to enact the changes Trump seeks.
Many conservationists who are already concerned about the environmental impacts of ethanol are staunchly opposed to this move. They fear not just the potential for greater smog formation, but other environmental impacts like greater fertilizer runoff into the watershed as corn production is expanded. The oil industry is also opposed to such a move, as it fears that what is permitted today will be mandated tomorrow. (See U.S. Ethanol Policy Under Siege).
But there is enough support among farm state legislators that President Trump will likely get his wish. Expect to see E15 at more gas stations in the near future. Whether that increases or reduces smog remains to be seen.
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