At the dawn of the automobile age, gasoline was the up-and-coming "alternative fuel" -- vying with electric batteries and steam power. Gas ultimately won out, of course. But now that we're running out of distilled dinosaur juice -- or at the very least, getting sick of being at the mercy of OPEC -- a variety of 21st century alternatives to gasoline are entering the pipeline (so to speak).
Essentially, alcohol created from vegetable matter and mixed with gasoline or used undiluted and "straight up." E85 is the commercial name for the mix that is currently available at a growing number of gas stations around the country. It is 85 percent ethanol and 15 percent gasoline. GM and Ford both offer E85 compatible new cars and trucks designed to safely use this fuel (they can also run on regular gas).
The advantages of ethanol/E85 include lower emissions of unburned hydrocarbons (which form the precursors of smog) and the potential for a significant reduction in U.S. dependence on non-renewable, petroleum-based fuels. Also, most vehicles can be set up to operate on E85/ethanol at relatively low cost and there is no loss of performance or power. Ethanol fuel also degrades quickly in water and therefore presents a much lower risk to the environment than an oil or gasoline spill. (See http://www.e85fuel.com/index.php to learn more about E85 and ethanol fuels.)
Vegetable oil can cook your fries as well as power the vehicle that gets you to the drive-thru. An interesting historical fact is that diesel engines were originally designed to run on vegetable oil, not petroleum-based diesel fuel. Engines can still run on vegetable oil and help keep the air cleaner and reduce our country's dependence on the oil cartels by doing so.
Biodiesel is not the same as raw vegetable oil (though that can be run in diesel engines, too). It is, however, made from raw vegetable oil. Its chief advantage over raw vegetable oil is that it can be used in any compression-ignition (diesel) engine with little or no modification necessary. The use of raw vegetable oil in diesels requires pre-heaters and other fuel system upgrades. Biodiesel is also less toxic than table salt -- and degrades as fast as sugar. (See www.biodiesel.org for more information about biodiesel fuels.)
Electric cars have been offered to the public as recently as the mid-1990s, when GM's EV-1 went on sale in California and a few other states. The idea of eliminating combustion engines entirely has always had tremendous appeal. However, engineers have not yet overcome the problems of limited range (typically less than 100 miles per charge), lengthy recharge times (several hours/overnight) and relatively poor performance compared with gas-powered (or diesel) vehicles.
There are also environmental concerns, including the storage/recycling of hundreds of pounds of lead-acid battery packs (per car) and the source of the electricity used to charge those battery packs. In the U.S., a large portion of the electrical energy we use is generated by coal-fired utility plants. They produce millions of tons of carbon dioxide, a known greenhouse gas, each and every year. Until the environmental issues are resolved, it's not likely we'll see mass produced electric cars. Solar-powered vehicles are also in their developmental infancy and unlikely to see production anytime soon.
This technology uses a fuel cell to generate electricity, with liquid hydrogen as the "fuel." The electricity produced by the catalytic reaction in the fuel cell can then be used to run electric motors which propel the car. Unlike current electric cars, which have to be plugged in to recharge their batteries, a fuel cell vehicle creates its own electricity.
Hydrogen is the most abundant element and the energy is produced by a fuel cell free of harmful byproducts (water is the primary "emission"). However, practical problems remain: the economical mass production of pure hydrogen and the infrastructure (pipelines, refueling facilities, etc.) necessary to get the hydrogen to end users safely and efficiently. But several automakers -- including General Motors and Honda -- have prototype fuel cell vehicles under development and we may see a breakthrough sometime during the next five to 10 years. (See http://www.eere.energy.gov/hydrogenandfuelcells/fuelcells/basics.html for more information about fuel cells.)
Compressed Natural Gas
Like hybrid gas-electric vehicles, the use of compressed natural gas (CNG) is seen as a workable intermediate step between conventional gas-burning cars and a future form of propulsion which doesn't use gasoline. The U.S. has large reserves of clean-burning CNG and it is relatively easy to modify a conventional car engine to operate on this fuel. In addition, because CNG has long been used in the home, some of the necessary infrastructure to get CNG to end users is already in place. GM, Ford and Chrysler have been building CNG-capable cars and trucks for several years -- and offering them for sale to both private individuals and municipal fleets. The cost per car is roughly $1,500 to $4,000 more than a gas-only version of the same vehicle.
While development of these future fuels continues, the automakers are also devoting much effort to continuous refinement of the century-old internal combustion engine. Today's gas engines run cleaner and more efficiently than ever before -- with no loss of power or performance. Technologies being used today to maximize each and every drop of gasoline include:
Variable displacement/displacement on demand
This system, which is used in several new GM and Chrysler vehicles, allows for some of the engine's cylinders to be shut down when they're not needed. Chrysler's 5.7 liter Hemi V-8, for example, can operate in four-cylinder mode under light load conditions -- automatically reverting to all eight cylinders when the driver needs the power. This improves fuel economy by 10 percent or more and substantially lowers emissions of both smog-forming compounds and greenhouse gasses.
Variable cam/valve timing
Similar in concept to displacement on demand, this technology gives an engine two distinct personalities. At low speed/light throttle, the engine is quiet, docile and highly efficient. But as the driver demands more power, the cam/valve timing becomes more aggressive -- delivering max power for as long as the driver wants it. Honda pioneered this technology with its VTEC system, which first appeared in the Acura NSX more than 15 years ago. Today, almost every major automaker uses some form of variable valve/cam timing to maximize efficiency and power without compromising either.
Catalytic converters are chemical exhaust scrubbers which convert harmful exhaust byproducts into harmless compounds such as water vapor. They've been in use since 1975 and have helped to dramatically lower the emissions output of the typical car or truck (the average new car produces a mere fraction of the harmful emissions of a pre-controlled car). However, to work at peak efficiency, a catalytic converter must be heated to very high temperatures, very quickly. During the first few minutes of "cold start" operation a converter isn't especially efficient. The solution has been to place the converter on today's cars as close to the engine as possible. The result is faster "light off" for the converter and lower overall emissions.