U.S. exports of methyl tert-butyl ether (MTBE), a motor gasoline additive, fell to 38,000 barrels per day in 2017, according to the U.S. Energy Information Administration. Overall, the exports account for 0.7% of U.S. petroleum product exports, and MTBE exports primarily go to Mexico, Chile and Venezuela.
In the United States, MTBE was commonly used until the late 2000s, when it was phased out as a result of water contamination concerns. Since then, fuel ethanol has replaced MTBE as a gasoline additive. MTBE boosts octane to improve combustion in gasoline engines.
In 2017, Mexico received 66% of U.S. MTBE exports. Economic instability in Venezuela has likely led to the decline in exports to that country recently. In those countries, MTBE is used as an oxygenate instead of a fuel ethanol, partly because it has lower evaporative emissions, can be shipped in pipelines along with finished petroleum products and doesn’t require ethanol-related infrastructure investments.
Nearly all U.S. MTBE exports originate from the Gulf Coast, where it’s produced. It can be blended with motor gasoline blendstock in the United States to make a finished product that’s sent to Mexico.
In 1999, the U.S. blending of MTBE into motor gasoline peaked at 260,000 barrels per day, while the volume of fuel ethanol added into motor gasoline was 38,000 barrels per day. Between 2000 and 2007, 23 states established partial or complete bans of MTBE blended into motor gasoline. The use of fuel ethanol replaced domestic MTBE consumption and has been supported by tax subsidies, including the Volumetric Ethanol Excise Tax Credit and the Renewable Fuel Standard, which mandates the use of biofuels in the U.S. transportation supply. Nearly all U.S. motor gasoline contains 10% fuel ethanol blends.