Pros and Cons of Ethanol

Pros

Because ethanol can be made from so many different substances, it can be made nearly anywhere from nearly any raw material. Most ethanol is made from corn and sugarcane, though other sorts of biomass may be used. Cellulose from grass or hay, cardboard, paper, farm wastes, and other waste products could potentially produce much more energy per source than is currently possible, with the side benefit of using up organic waste matter that would otherwise be thrown into landfills.

Ethanol does not emit the same greenhouse gases that gasoline does. When it burns, it emits only carbon monoxide and water. Air quality improves quickly when ethanol replaces gasoline.
Ethanol is less flammable than gasoline and thus may be less of a fire hazard. When it does catch on fire, however, its flame and smoke are very hard to see, which presents another set of risks. Ethanol and other alcohol fuels dissolve in water, so water will put out alcohol fires, unlike gasoline fires, which require special fire extinguishers.

Ethanol will dissolve rubber and plastic, so pure ethanol cannot be used in unmodified gasoline engines. Corrosive ethanol cannot be transported in petroleum pipelines, so more-expensive over-the-road stainless-steel tank trucks increase the cost and energy consumption required to deliver ethanol to the customer at the pump.

Ethanol's octane rating is higher than gasoline, which can require modifications to spark timing, carburetor jets, and starting systems. Gasohol does not present the same problems and can be used in ordinary vehicles without modification.

Ethanol has the potential to reduce garbage in landfills. If ethanol can be made from waste paper or wood, that would supply a use for what has historically been a big source of trash. On the other hand, the process of creating ethanol from waste cellulose itself creates waste products that cannot be used.

Cons

Unfortunately ethanol production comes with a substantial environmental dilemma. Ethanol made from corn is actually worse for the environment than fossil fuels because it takes more energy to raise the corn and make ethanol than the resulting ethanol can itself provide. Commercial farms use vast amounts of fossil fuels in planting, harvesting, and fertilizing their crops, making the ethanol and transporting it. In the US the corn ethanol industry has been heavily subsidized by the government, which makes it seem inexpensive to manufacture. If, however, the industry uses more energy to make ethanol than ethanol can provide, then ethanol is in fact not a sustainable alternative to gasoline.

In areas where it is easy to make ethanol, such as Brazil, with its ample water and warm climate that makes it easy to grow sugarcane, ethanol is an entirely viable fuel. Brazil powers its ethanol plants by burning bagasse, the sugarcane solids, which can generate enough power to have some left over. Hydroelectric power is also a good way of making ethanol without using fossil fuels.