For four decades, ethanol has been successfully used to reduce harmful tailpipe emissions from motor vehicles. By displacing hydrocarbon substances like aromatics in gasoline, ethanol helps reduce emissions of air toxics, along with particulate matter, carbon monoxide, nitrogen oxides and exhaust hydrocarbons. These pollutants cause smog and ground-level ozone and adversely affect human health.
Since the Clean Air Act Amendments were adopted in 1990, ethanol has helped reduce the concentration of carbon monoxide in our air by 77%, nitrogen oxides by 50%, fine particulate matter by 41%, and low-level ozone by 22%. Cutting these emissions results in lower incidence of respiratory illness and asthma, heart disease, lung disease and cancer – and ultimately fewer premature deaths.
But ethanol does more than reduce tailpipe pollution that causes smog and illnesses. It also significantly reduces greenhouse gas emissions linked to climate change.
Plants that are ultimately made into renewable fuels absorb carbon dioxide—the most abundant greenhouse gas—from the atmosphere as they grow, and that same amount of carbon dioxide is re-released when the renewable fuel is produced and combusted in an engine. In this way, renewable fuels like ethanol simply recycle atmospheric carbon—unlike fossil fuels that remove carbon that had been sequestered underground for millions of years and vent it into the atmosphere.
According to recent studies and modeling by the U.S. Departments of Energy and Agriculture, corn ethanol from a typical dry mill reduces GHG emissions by 40-45% compared to gasoline. These estimates include emissions from hypothetical “land use changes,” even though EPA estimates that agricultural land use in the United States has declined since the Renewable Fuel Standard was expanded in 2007.
In fact, ethanol is responsible for roughly half of the GHG reductions achieved under California’s Low Carbon Fuel Standard and almost 60% of the GHG reductions achieved under Oregon’s Clean Fuels Program.
Nationwide, the use of ethanol in gasoline in 2018 reduced GHG emissions from the transportation sector by 55.1 million metric tons. That’s equivalent to removing 11.7 million cars from the road for an entire year or eliminating the annual emissions for 13 coal-fired power plants.
[Source: RFA analysis using U.S. Dept. of Energy GREET model]