Ethanol production uses plant matter to create a biofuel suitable for combustion engines, usually mixed with 85 percent to 90 percent gasoline. In America, biofuel mostly comes from excess corn, and in the years since its development, it has found widespread use across the country. While ethanol offers some advantages over fossil fuels, however, it still has a number of disadvantages that scientists need to overcome before it can become a true replacement for oil.
The chief advantage of ethanol is that it is a renewable fuel. You can make ethanol out of virtually any kind of plant matter, from corn and sugar cane to switch grass and other nonfood crops. Ethanol burns cleaner than gasoline, producing less soot and emissions. In addition, unlike fossil fuels, which release long-stored carbon from beneath the earth, the cycle of carbon in ethanol is much shorter. When farmers replant crops to grow new fuel, they help absorb some of the carbon dioxide released during production and combustion.
One of the biggest problems with ethanol in its current form is its energy return on investment, or EROI. For instance, The EROI of oil is around 11:1, which means oil provides around 11 times more energy than it costs to extract it. The EROI of ethanol is a topic of debate, with most studies suggesting an EROI of corn ethanol around 1.5:1, making it a less efficient fuel. Other forms of ethanol, however, may provide higher EROI rates, with sugar cane ethanol running at 8:1 and switch grass ethanol possibly offering a higher ratio. As oil becomes scarcer and harder to extract and advances in technology reduce the energy required to distill biofuel, ethanol may become a more attractive option.
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The expense of distilling ethanol is another substantial issue with the fuel. Corn ethanol is considerably more expensive to create than gasoline, and poor harvests and scarcity can significantly affect prices from year to year. Many states are running trials of an 85 percent ethanol blend for specially designed vehicles, and the increase in demand for E85 could put even more pressure on supplies and drive prices up. The government subsidizes ethanol production to keep it competitive as a fuel additive, but the technology has some ways to go before ethanol can compete on its own.
Another problem with ethanol is that it has the potential to damage engines in traditional cars and trucks. Ethanol is more corrosive than gasoline, and it is more prone to picking up dirt and other contaminants that can damage fuel systems. Most cars on the road can handle 10 percent ethanol blends, but states that test 15 percent blends restrict it to cars and trucks built after 2001. Older vehicles may also have problems with the difference in combustion temperature, running rougher on an ethanol blend than on pure gasoline.