Ethanol is nontoxic and biodegradable
Unlike gasoline, pure ethanol is nontoxic and biodegradable, and it quickly breaks down into harmless substances if spilled. Chemical denaturants are added to fuel ethanol (about 2% by volume), and many of the denaturants used are toxic. Similar to gasoline, ethanol is a highly flammable liquid and must be transported carefully.
Ethanol can reduce pollution
Ethanol and ethanol-gasoline mixtures burn cleaner and have higher octane levels than pure gasoline, but they also have higher evaporative emissions from fuel tanks and dispensing equipment. These evaporative emissions contribute to the formation of harmful, ground-level ozone and smog. Gasoline requires extra processing to reduce evaporative emissions before it is blended with ethanol.
Ethanol can be considered atmospheric carbon-neutral because the plants used to make fuel ethanol (such as corn and sugarcane, the two major feedstocks for fuel ethanol production) absorb carbon dioxide (CO2) as they grow and may offset the CO2 produced when ethanol is made and burned. In the United States, coal and natural gas are used as heat sources in the fermentation process to make fuel ethanol.
The impact of greater ethanol use on net CO2 emissions depends on how ethanol is made. It also depends on whether or not indirect impacts on land use are included in the calculations. Growing plants for fuel is a controversial topic because some people believe the land, fertilizers, and energy used to grow biofuel crops should be used to grow food crops instead.
The U.S. government is supporting efforts to produce ethanol with methods that use less energy than conventional fermentation, and that use cellulosic biomass, which requires less cultivation, fertilizer, and pesticides than corn and sugar cane. Cellulosic ethanol feedstock includes native prairie grasses, fast growing trees, sawdust, and even waste paper.