Ethanol Fuel (Corn, Sugarcane,

Switchgrass)

Blake Liebling

Ethanol is a form of renewable energy that can be produced from agricultural feedstocks. It can be made from common crops like corn and sugarcane.

Ethanol is most often used as a motor fuel, mainly as a biofuel additive for gasoline.

Most cars in the United States can run on blends of up to 10 percent ethanol and the use of 10 percent ethanol gasoline is mandated in some U.S. states and cities.

Background

World ethanol production for transport fuel tripled between 2000 and 2007 from 17 billion to more than 52 billion liters.

From 2007 to 2008, the share of ethanol in global gasoline type fuel use increased from 3.7% to 5.4%.

In 2010 worldwide ethanol fuel production reached 86.9 billion liters, with the United States as the top producer with 50 billion liters, accounting for 57.5 percent of global production.

Ethanol fuel has a gasoline gallon equivalency (GGE) value of 1.5 US gallons

Use of Ethanol

Switchgrass: Low-input perennial grass. Ethanol production depends on development of cellulosic technology. Breeding efforts are underway to increase yields. Higher biomass production possible with mixed species of perennial grasses.Sugar Cane:Long-season annual grass. Used as feedstock for most bioethanol produced in Brazil. Newer processing plants burn residues not used for ethanol to generate electricity. Grows only in tropical and subtropical climates.Corn:High-input annual grass. Used as feedstock for most bioethanol produced in USA. Only kernels can be processed using available technology

Different Types

The basic steps for large scale production of ethanol are: microbial (yeast) fermentation of sugars, distillation, and dehydration.

After Ethanol is fermented, it is distilled and dehydrated in order to remove excess water. This water must be removed in order to use ethanol as a fuel.

Making Ethanol

First, ethanol is a renewable, relatively safe fuel that can be used with few engine modifications.

The second benefit of ethanol is that it can improve agricultural economies by providing farmers with a stable market for certain crops, such as maize and sugar beets.

Ethanol is nontoxic and biodegradable, it quickly breaks down into harmless substances if spilled.

Because ethanol is made from crops that absorb carbon dioxide and give off oxygen it has a potential to reduce greenhouse gas emission and help maintain the balance of carbon dioxide in the atmosphere.

Advantages

Growing it takes a lot of land and energy, and most crops are sprayed with pesticides

You get 12 to 15% less fuel mileage with it you don't get as good mileage with ethanol as gasoline

It also drives up the price of our food as there isn't as much corn for the animals feed.

Ethanol corrodes iron parts slightly.

Disadvantages

Compared with conventional unleaded gasoline, ethanol is a particulate-free burning fuel source that combusts with oxygen to form carbon dioxide, water and aldehydes.

Gasoline produces 2.44 CO2 equivalent kg/l and ethanol 1.94.

However since ethanol contains 2/3 of the energy per volume as gasoline, ethanol produces 19% more CO2 than gasoline for the same energy

Large-scale farming is necessary to produce agricultural alcohol and this requires substantial amounts of cultivated land.

Impact on Environment

As ethanol yields improve or different feedstocks are introduced, ethanol production may become more economically feasible in the US.

Currently, research on improving ethanol yields from each unit of corn is underway using biotechnology. Also, as long as oil prices remain high, the economical use of other feedstocks, such as cellulose become viable.

Fast growing species like switchgrass can be grown on land not suitable for other cash crops and yield high levels of ethanol per unit area.

Looking Ahead