biology Enlish(10)

corn, sugar beets, sugar cane, molasses and any sugar or starch that alcoholic beverages can be made from (like potato and fruit waste, etc.). The ethanol production methods used are enzyme digestion (to release sugars from stored starches, fermentation of the sugars, distillation and drying. The distillation process requires significant energy input for heat (often unsustainable natural gas fossil fuel, but cellulosic biomass such as bagasse, the waste left after sugar cane is pressed to extract its juice, can also be used more sustainably).

Ethanol can be used in petrol engines as a replacement for gasoline; it can be mixed with gasoline to any percentage. Most existing automobile petrol engines can run on blends of up to 15 percent bioethanol with petroleum/gasoline. Gasoline with ethanol added has higher octane, which means that your engine can typically burn hotter and more efficiently. In high altitude (thin air) locations, some states mandate a mix of gasoline and ethanol as a winter oxidizer to reduce atmospheric pollution emissions.

Ethanol fuel has less BTU energy content, which means it takes more fuel (volume and mass) to produce the same amount of work. An advantage of ethanol is that is has a higher octane rating than ethanol-free gasoline available at roadside gas stations and ethanol's higher octane rating allows an increase of an engine's compression ratio for increased thermal efficiency. Very-expensive aviation gasoline (Avgas) is 100 octane made from 100 percent petroleum with toxic tetra-ethyl lead added to raise the octane number. The high price of zero-ethanol Avgas does not include federal-and-state road-use taxes.

Ethanol is very corrosive to fuel systems, rubber hoses and gaskets, aluminum, and combustion chambers. Therefore, it is illegal to use fuels containing alcohol in aircraft (although at least one model of

ethanol-powered aircraft has been developed, the Embraer EMB 202 Ipanema). Ethanol also corrodes fiberglass fuel tanks such as used in marine engines. For higher ethanol percentage blends, and 100 percent ethanol vehicles, engine modifications are required.

It is the hygroscopic (water loving) nature of relatively polar ethanol that can promote corrosion of existing pipelines and older fuel delivery systems. To characterize ethanol itself as a corrosive chemical is somewhat misleading and the context in which it can be indirectly

corrosive is somewhat narrow (that is, limited to effects upon existing pipelines designed for petroleum transport.

Corrosive ethanol cannot be transported in petroleum pipelines, so

more-expensive over-the-road stainless-steel tank trucks increase the