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 in fuel ethanol make up about 2% of fuel ethanol by volume, and many of the denaturants 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 blending with ethanol.
Producing and burning ethanol results in emissions of carbon dioxide (CO2), a greenhouse gas. However, ethanol is considered atmospheric carbon-neutral because corn and sugarcane, the two major feedstocks for fuel ethanol production, absorb CO2 as they grow and may offset the CO2 produced when ethanol is made and burned. Some ethanol producers burn coal and natural gas for heat sources in the fermentation process to make fuel ethanol, while some burn corn stocks or sugar cane stocks.
The effect that increased ethanol use has on net CO2 emissions depends on how ethanol is made and 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 or sugar cane. Cellulosic ethanol feedstock includes native prairie grasses, fast growing trees, sawdust, and even waste paper.