First, ethyl alcohol or ethanol is a bio-based fuel produced from the fermentation of plant matter. Early humans knew about ethanol thousands of years ago. More recently, we’ve used it as fuel. In fact, some of the first internal combustion engines used ethanol — long before gasoline.
Unlike petroleum fuels, bio-based fuels such as ethanol reduce lifecycle carbon emissions. The plants from which biofuels are made take up carbon dioxide as they grow. Using fossil fuels like gasoline derived from crude oil unleashes “fossil” carbon that’s been locked up underground in rock for millions of years.
What is E10?
E10 is a biofuel blend comprised of 90% regular unleaded gasoline and 10% ethanol. About 98% of all gasoline sold in the U.S. today is E10.
Biofuel blends like E10 were used on and off in the early years of the American automobile. In the Midwest, where farmland was plentiful and crop prices were often abysmal, E10 became known as “gasohol,” or “the farmers’ fuel,” during the Great Depression.
The use of E10 became more widespread nationwide following the passage of amendments to the Clean Air Act in 1990. The amended law required the use of oxygenated (meaning oxygen-added) gasoline in metropolitan areas with high air pollution levels. Oxygen aids fuel combustion, allowing it to burn more cleanly, and the ethanol molecule is 35% oxygen. An E10 blend contains 3.5% oxygen, which led to it quickly becoming the oxygenated gasoline of choice — helping to solve urban air quality problems such as those experienced in Minneapolis-Saint Paul, Duluth, and St. Cloud of the 1970s to 1990s.
Ethanol also boosts octane, which translates to higher engine horsepower and performance. As automakers seek ways to improve fuel economy, they’ve moved to smaller, higher-compression engines that are optimized to higher octane fuels. Adding 10% ethanol increases a base fuel’s octane rating by about three points. That ethanol is also safer, cleaner-burning, and less expensive than toxic petroleum-based octane options.
Today, E10 is sold in every state, and it’s been Minnesota’s fuel of choice for more than 30 years. The Renewable Fuel Standard (and high oil prices) have helped ethanol and other biofuels gain access to the fuel marketplace, though it’s still dominated by petroleum.
Is E10 compatible with all vehicles?
Absolutely. E10 is approved for all motor vehicles and small engines sold in the United States in the last 35 years. While all gasoline vehicles can use E10, some special models may use even higher ethanol blends known as flex fuels, the most common of which is E85. More than 20 million E85-capable flex fuel vehicles are on American roads.
In summary, E10 is the gasoline-biofuel blend we’ve all been using for decades. It’s been a hedge against oil price shocks, helped reduce air pollution and overseas oil imports, and boosted octane. In Minnesota where we have no oil resources of our own, renewable ethanol has been a closer-to-home solution for urban centers that need cleaner fuel and the rural agriculture economy that can supply it.
How does E10 compare to regular unleaded gasoline?
Will you notice a fuel economy difference when using E10 versus a non-ethanol gasoline? Unlikely. The energy density of the fuels are within a couple of percent of each other, and modern engines adjust to both. Remember: road conditions, weather such as temperature and wind, your speed and driving habits, and carrying extra weight in the trunk (e.g., golf clubs or hockey equipment) can reduce your vehicle’s fuel economy by 10% to 20%.