Ethanolblended

Ethanolblended fuels are gasoline products in which ethanol is mixed with hydrocarbon gasoline. The term commonly refers to blends such as E10, E15, and E85, where ethanol comprises around 10%, 15%, or up to 85% of the blend by volume. Ethanolblended fuels are used to reduce fossil fuel use, improve octane, and lower certain greenhouse gas emissions on a life-cycle basis, although the overall environmental impact depends on feedstock and production methods.

Most ethanol is produced from renewable biomass, including corn in the United States and sugarcane in Brazil. Blends are distributed through conventional gasoline networks and sold at many retail stations. E10 is the most widely available form; E85 is designed for flex-fuel vehicles capable of operating on high-ethanol blends.

Advantages include higher octane rating and potential reductions in some air pollutants and greenhouse gas emissions. Economic benefits include support for agriculture and rural economies, and energy security considerations.

Limitations include ethanol's lower energy density, which reduces fuel economy relative to pure gasoline. Ethanol can attract moisture, causing phase separation in some storage conditions, and can be more corrosive to certain materials. High-ethanol blends may require engine management or fueling-system compatibility considerations, and cold-weather starting can be affected.

Regulation and policy frameworks include the Renewable Fuel Standard in the United States, which sets blending volumes, and similar programs in the European Union and Brazil. These regimes influence feedstock choices, infrastructure investment, and market dynamics.

Environmental impacts vary with feedstock and farming practices. Life-cycle analyses can show greenhouse gas reductions relative to gasoline, but results depend on land-use change, water use, and fertilizer inputs. Ethanolblended fuels remain a subject of ongoing assessment in energy and environmental policy.