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New study investigates metal deterioration from ethanol-blended gasoline
Due to the spiraling crude oil prices, refining companies along with federal governments are seriously considering alternative fuel strategies. These efforts involve blending alternate fuels, such as ethanol and biodiesel, into gasoline and diesel, respectively. For example, 5% blending of ethanol into gasoline is mandatory in several Indian states. In addition, the Indian government is proposing to increase the ethanol content to 10% in gasoline blends.
Ethanol-blended gasoline will aid in reducing particulate emissions for compression-ignition engines due to more efficient combustion. Conversely, ethanol-blended gasoline can accelerate corrosion for susceptible metals used in the fuel infrastructure such as pipelines, storage tanks, car-fueling systems, etc. Ethanol's hygroscopic nature fosters the corrosion processes.
Gasohol
Ethanol-blended gasoline is commonly known as gasohol. Gasohol refers to ethanol's greater affinity to water; ethanol-blended gasoline can absorb significant amounts of water (0.3 vol%/vol% to 0.5 vol%/vol%) without phase separation. The soluble water in the ethanol attacks metal and thus causes corrosion. Accordingly, corrosion inhibitors are added to ethanol-gasoline blends to reduce corrosion processes. The following examples report the effects of gasohol on corrosion rates for different construction materials, including carbon steel (CS), brass and copper.
Energy-security options
The global energy/fuel crisis has triggered the awareness among many nations to develop energy-security and alternative-fuel programs. When ethanol is added to gasoline, it modifies the fuel properties, and it does affect exhaust and emissions from vehicles. In India, a 5% ethanol-fuel blend is referred to as E5, and E5 transportation fuel is mandatory for consumers. There are discussions to increase the ethanol concentration to 10% or E10. In European countries, ethanol blending in gasoline ranges from 20% to 85% ethanol. Brazil uses 100% ethanol as a transportation fuel.
Ethanol and gasoline have different physical properties such as octane number, vapor pressure, etc. Ethanol-blended gasoline has a higher vapor pressure and a better octane number than the individual components. The important property changes are higher vapor pressure and octane number of the blended compounds to the base gasoline. They are enhancements to the air-to-fuel ratio and dilution effect of gasoline. 1
Distribution issues
Ethanol is not easily transported via pipelines because it has a tremendous affinity to absorb water. Water accumulation in pipelines is a...