There is a lot of talk these days about "alternative fuels." But just what are these alternative fuels, and why is everyone so excited about them?
In the simplest terms, an alternative fuel is any fuel other than gasoline or diesel. Since many alternative fuels are also renewable — and can be produced here in the U.S. — they could reduce our dependence on foreign oil.
Alternative fuels such as biodiesel, ethanol and methanol, have been produced and used on a small scale for decades. They are now being rediscovered due to the rising cost of oil and the instability of world politics. Here's where our oil is imported from — it may surprise you to read who the top supplier is.
Before we get to the specifics, let's clear up a related point. There is a big difference between "energy" and "fuel," even though the terms are used interchangeably. While it is often said that we are in an "energy crisis," this isn't accurate. Energy exists all around us in many different forms. The problem is that energy needs to be stored and transported as fuel. So, technically speaking, we should talk about a "fuel shortage," not an "energy crisis."
To help you better understand this developing area of technology, we've put together a list of the most commonly mentioned alternative fuels and given a brief description of each one.
Biodiesel is used to refer to renewable fuels that can be burned in a diesel engine. Biodiesel is most often made from the oil extracted from a variety of plants, such as peanuts or soybeans, although it can also be made from animal fats. Vegetable oil needs treatment before it can be burned in a diesel engine. Biodiesel can be used at 100 percent strength or blended with petroleum-based diesel fuel, and is used in diesel engines without any modification to the engine. It is both non-toxic and biodegradable. It is nearly free of sulfur and carcinogenic benzene — two of the components of petroleum diesel that the Environmental Protection Agency (EPA) and state emissions boards have issued regulations on because of environmental and health concerns. The main drawback to biodiesel is that it is not widely available yet.
Compressed Natural Gas (CNG) is widely used for heating, cooking and cooling. When it is compressed and stored in a fuel tank, it can be used as a very clean-burning fuel for cars and trucks. Gas-burning engines can easily be modified to run on CNG, but there is only one car widely available to the public that uses this fuel, the Honda Civic GX. Currently, natural gas is a cheaper form of fuel for cars than gasoline, but CNG pumps are hard to find and CNG cars don't go as far on a tank of fuel as gasoline-powered vehicles. Most CNG vehicles are part of commercial fleets (taxicabs, municipal buses, etc.) that have their own pumps on-site for convenient refueling.
Electric cars run on electrical power stored in batteries. These cars produce no emissions. However, the power plants that generate electricity are often fueled by coal, which does produce emissions that have an adverse effect on the environment. Aside from golf cartlike vehicles with top speeds of about 25 mph, the only pure electric car currently for sale is the Tesla Roadster. But some existing cars have been adapted to run on electric power. Hybrid vehicles use regenerative braking systems to charge electric batteries and, as such, are partly electric.
Ethanol is a form of alcohol often produced from corn or sugar cane, and has a higher octane rating than gasoline. Like other alcohols, ethanol can be used as a fuel in gasoline engines. Ethanol is blended with gasoline and used in cars with little or no modification of the engine. Gasohol is a mixture of about 10-percent ethanol and 90-percent gasoline and will run in an unmodified car. In fact, when you fuel up at a gas station in many U.S. states, this is exactly what you're buying. E85 is 85 percent ethanol and 15 percent gasoline and can used in a flexible fuel vehicle (FFV) — a vehicle with a motor set up to run on gasoline or blends of gasoline and ethanol. You can find a list of flexible fuel vehicles at this link. There is a heated debate about the economics of producing ethanol.
Fuel-cell cars are often found on lists of alternative-energy vehicles. These cars have been in development for years and use a sophisticated electrochemical energy conversion device similar to a battery. The power is then put to the wheels via an electric motor. The core source of energy is hydrogen, which is sometimes extracted from water. Despite the appeal of fuel-cell cars an affordable, commercially available model is still a few years away.
Methanol is another alcohol derived from a variety of sources such as oil shale, coal, natural gas or agricultural waste. Like ethanol, it is clean-burning and will blend with gasoline. For years, straight methanol has been used in racecars because it has a high octane rating, making it a good fuel for high-compression engines.
Woodgas is a less commonly known alternative fuel produced from wood or "biomass" (agricultural byproducts). Woodgas-powered vehicles operated during World War II by putting a wood burner in the trunk, or trailer, and piping the gases into the carburetor. Scientists are studying ways to run generators and even vehicles on more sophisticated "gasifiers." More information is available from the Biomass Energy Foundation (BEF).