Some of the
newest fuel options intended to make road travel nearly pollution free seem almost like alchemy – turning lead into gold.
Scientists are now taking materials that have traditionally been discarded, from grass clippings and chips to used vegetable oil, and creating clean, green fuels. Other researchers are looking at ways to turn energy from the sun into horsepower, giving a whole new meaning to the term sunroof.
Biofuels, one of the biggest groups of new fuels, include alcohols, ethers, esters, and other chemicals made from plants, agricultural and forestry leftovers, and a large portion of municipal solid and industrial waste.
Biofuels used for transportation include bioethanol, biodiesel, biomethanol, and pyrolysis oils.
Unlike petroleum based fuels, biofuels are rapidly biodegradable. An accidental biofuel spill would have minimal impacts on wildlife and the environment, advocates say. They also argue that biofuels burn more cleanly and completely, resulting in less pollution since fewer petroleum pollutants are released into the air and water.
Additionally, environmentalists maintain that biofuels provide roughly the same efficiency as petroleum-based fuels. Whether true or not, an increasing number of government and company fleet cars are using biofueling stations.
But there aren’t many biofuel stations out there for the average consumer.
In the United States, the two most common types of biofuels are bioethanol and biodiesel. Aside from being cleaner, they may also prove cheaper, especially since they can be home-grown, decreasing dependence on foreign oil imports.
Ethanol is the most widely used biofuel today. More than 1.5 billion gallons are added to gasoline in the United States each year to improve vehicle performance and reduce air pollution.
Ethanol is an alcohol, and most of it is made using a process similar to brewing beer. Startch crops, like corn, are converted into sugars, which in turn are fermented into ethanol and distilled into its final form. Ethanol made from waste materials instead of specially grown crops is called bioethanol.
As a gasoline additive, ethanol is used to increase the octane, or energy content, and reduce harmful emissions. But it can also be used alone as a fuel, either burned in an engine directly, or used to create hydrogen to power a fuel cell.
Both Ford and Chrysler sell flexible fuel vehicles, which can run either on gasoline or a blend of 85 percent ethanol and 15 percent gasoline.
This fuel can be made from using edible oils, such a french-fry grease, conjuring images of turning fast-food restaurants into combined food and fuel depots. In reality, making biodiesel is not as simple as pouring fry oil into your gas tank.
For years, scientists have been producing and testing biodiesel fuel, made by converting vegetable oils or animal fats into diesel fuel, as an alternative to petroleum based diesel fuel, or “petrodiesel.”
US production of biodiesel is about 30 million gallons per year and growing. Biodiesel is used in some federal, state, and transit fleets, at marinas, and in tourist boats and launches. There is a growing interest in using biodiesel where workers are exposed to diesel exhaust, in aircraft to lessen local pollution near airports, and in locomotives that face restricted use unless emissions can be reduced.
Traditionally, biodiesel is made by mixing used oil and an alcohol such as ethanol with a base liquid. Over several hours, a chemical reaction turns the mixture into biodiesel and glycerol. The products must be allowed to sit for several more hours or days so that they separate into easily retrievable fuels.
A new process, announced in March, was developed at the Department of Energy’s Idaho National Engineering and Environmental Laboratory. Researchers Bob Fox and Dan Ginosar found that used french-fry oil can be converted into an environmentally friendly diesel fuel faster and less expensively than current processes while producing an even higher grade fuel.
Fox and Ginosar accomplished this by developing a system using a catalyst fixed in the solution. The solvent is constantly recycled, in the processing solution, leaving it out of the finished product. The result is a better separation of biodiesel and glycerol, and a cleaner, higher grade of both substances.
When the new biodiesel is burned, it smells a lot like fried chicken, so much so that when the National Park Service began considering using biodiesel fuel for its tour buses, it worried that bears would chase the vehicles, thinking they were chasing finger licking good meals on wheels.
“We told the Park Service that bears don’t often eat at Kentucky Fried Chicken,” Fox said.
Other alternatives exist to biofuels.
Researchers at Penn State University are working on a way to run vehicles with clean burning dimethyl ether, or DME, the chemical that replaced fluoro-chloro carbons in spray cans. In a study of the emissions produced when burning DME as a substitute for butane or propane, the researchers found that DME had lower carbon monoxide emissions and the same or lower nitric oxide emissions than either commercially available fuel.
DME is normally produced from methanol, but DME production from natural gas and coal-derived syngas may open up this clean fuel for broader use, the researchers said.
Andre Boehman, director of the Penn State Combustion Laboratory, is planning to test DME-blend fuel in a school bus that normally uses petrodiesel fuel.
Using solar panels to convert energy from the sun directly into power to run a vehicle creates perhaps the cleanest cars ever.
Incoming solar radiation light from the sun is captured by the photovoltaic panels on top of the car. They make electricity, which is then stored in batteries. The electric motor draws energy from the batteries to move the car.
There are drawbacks, however.
These cars need sunlight to run, and most cannot store enough energy to keep going overnight, or even on a cloudy day. In addition, most solar vehicles must make a tradeoff between the distance they can travel and the top speed they can reach. Solar cars can either travel all day, slowly, or run at higher speeds over shorter distances.
Still, competitions are held worldwide every year to develop a prototype solar vehicle. One such event, the World Solar Challenge, is a road race that promotes research and development into practical ways of harnessing solar energy for transportation. Held every three years since 1987, the race covers a 3,010 kilometer (1,870 mile) course between Darwin and Adelaide, Australia.
The current edition of the race begins 17 October.
Copyright Environment News Service (ENS) 1999
This is is a syndicated post. Read the original at www.wired.com