The use of oxygenates in gasoline has been a contentious issue for decades. One oxygenate commonly used in the United States gasoline was methyl tert-butyl ether (MTBE). However, due to concerns about its impact on the environment and human health, its use has been substantially phased out since the early 2000s.
Click here for Part 1 of The Importance of Oxygenates in Gasoline.
MTBE was used as an oxygenate in gasoline to help reduce emissions of harmful pollutants such as carbon monoxide and VOCs. Raising the level of molecular oxygen in fuels has been shown to make fewer (lower levels of) harmful emissions when burned in an engine. However, serious concerns about MTBE's impact on drinking water supplies emerged in the 1990s.
MTBE is highly soluble in water and was found to be contaminating groundwater supplies when gasoline leaked from underground storage tanks in various locales. Even tiny amounts of MTBE were enough to render the drinking water for entire communities undrinkable because of the taste. The potential health effects of exposure to MTBE also raised concerns, as it was found to be a possible carcinogen that might have been linked to other adverse health effects.
In the late 1990s, the issue of MTBE in gasoline came to a head when several states began to ban its use. California was the first state to ban MTBE in 1999, followed by New York and Connecticut in 2003. The ban on MTBE in California was partly due to the discovery of contaminated drinking water supplies in several areas of the state. Bans on MTBE in other states followed suit, with many citing concerns about the impact of the oxygenate on the environment and human health.
As MTBE founds itself prohibited in more and more states, other oxygenates, such as ethanol, began to be used instead. Ethanol is a renewable alcohol fuel that can be made from corn, sugarcane, or other crops. In the United States, corn is the most common source. Other areas of the world, like Brazil, make it primarily from sugarcane and switchgrass (and do it very well).
One of the primary benefits of using ethanol as an oxygenate is its ability to reduce harmful emissions from gasoline. Unlike MTBE, which has been linked to a range of negative health effects, including cancer, ethanol is considered much safer for human health and the environment. It is a renewable fuel source that is produced domestically, reducing our dependence on foreign oil, and it produces fewer greenhouse gas emissions than traditional gasoline.
The use of ethanol as an oxygenate in gasoline has not been without controversy, however. Critics argue that ethanol production and use in fuel is not as environmentally friendly as proponents insist, and they point out debates on whether ethanol's production is as carbon-neutral as we'd like to think. There are also concerns about the impact of increased ethanol use on food prices, as substantial portions of the corn crop in the United States are diverted to be used to produce the fuel instead of being used for food.
Despite these concerns, ethanol has become the primary oxygenate used in gasoline in the United States. It has been helped by efforts by the federal government to promote the use of biofuels in the country's fuel supplies. The Energy Policy Act of 2005 mandated using a certain amount of biofuels in gasoline and on-road diesel fuel, with increasing amounts required over time. The Renewable Fuel Standard, which was established in 2007, also requires a certain amount of biofuels to be blended into gasoline each year.
The shift away from MTBE and towards ethanol as an oxygenate in gasoline has had significant implications for the refining industry. Refiners had to make significant investments to transition from MTBE to ethanol, including building new facilities and modifying existing ones. The shift has also impacted the supply chain for gasoline, with ethanol needing to be transported and blended with gasoline before it can be sold at the pump.
In conclusion, using oxygenates in gasoline has been a contentious issue for many years. The use of MTBE as an oxygenate was once common in the United States, but concerns about its impact on the environment and human health led to its gradual phase-out over the past few decades. Ethanol has become the primary oxygenate used in gasoline in the United States, despite concerns about its impact on the environment and food prices. The federal government has also taken steps to promote the use of biofuels such as ethanol through legislation such as the Energy Policy Act of 2005 and the Renewable Fuel Standard.
As we continue to rely on biofuels to reduce our dependence on foreign oil and combat climate change, it will be important to find sustainable and equitable solutions that balance the needs of the environment, the economy, and the people who depend on them.
Learn more about fuel, fuel storage, and fuel maintenance with our Fuel Pulse Podcast Episode 024 - Oxygenates (Part 2) or you may use the player below.