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Blended Fuels

Blended fuel usually refers to a mixture composed of automotive gasoline and another liquid, other than a minimal amount of a product such as carburetor detergent or oxidation inhibitor, which can be used as a fuel in a motor vehicle.

Typically, in the current sense of the term, a blended fuel is a mixture of traditional fuels (such as gasoline or diesel fuel) and alternative fuels (such as ethanol or biodiesel, respectively) in varying percentages. The lowest-percentage blends are being marketed and introduced to work with current technologies while paving the way for future integration. For example, B5 and B20 (diesel fuel blended with 5% or a 20%, receptively of a biofuel) can be pumped directly into the tank of any diesel-fueled vehicle. Ethanol is also blended (approximately 10% v/v) into much of the gasoline dispensed in many countries, especially in metropolitan areas, to reduce emissions.

The use of blended fuels is part of the transition to using more alternative fuels. Although the pure alcohol (methanol or ethanol) will burn independently, cold weather starting can be a problem. An engine has to be designed exclusively for a particular fuel to take advantage of all the characteristics of that fuel. Without the infrastructure in place to support pure alcohol fuels, flex-fuel vehicles (FFVs) have been designed to run on both alcohol and gasoline. The flex-fuel vehicles join the best characteristics of both methanol and gasoline (or ethanol and gasoline) and make it possible to utilize higher blend percentages such as E85 (ethanol) and M85 (methanol). Examples of blended fuels are presented below.

E10

E10 is a low-level blend composed of 10% ethanol and 90% gasoline that has been approved by the United States Environmental Protection Agency (EPA) for use in any conventional, gasoline-powered vehicle. The use of E10 was spurred by the Clean Air Act Amendment of 1990 (and subsequent laws), which mandated the sale of oxygenated fuels in areas with unhealthy levels of carbon monoxide. Currently, the E10 fuel is sold in every state.

E15

E15 is a low-level blend composed of 10.5 to 15% v/v ethanol and gasoline and is approved for use in newer light-duty conventional vehicles. Stations must adhere to several EPA requirements and regulations when selling E15.

E85

E85 (or flex fuel) is an ethanol-gasoline blend containing 51 to 83% v/v ethanol, depending on geography and season that qualifies as an alternative that can be used in flexible fuel vehicles (FFVs), which have an internal combustion engine and are designed to run on E85, gasoline, or any blend of gasoline and ethanol up to 83% v/v.