The Fuels of the Future: Farming the World's Energy
Agriculture offers the first serious alternatives to fossil fuels: Diesel, natural gas, and petroleum could give way in the future to "biomass" energy. As development continues apace, so too do concerns about the farmed fuels' effectiveness.
Six years ago, Germany's Volkswagen opened Autostadt, or "Motor City," in the western city of Wolfsburg. It's the most impressive park the German automobile industry has ever created to celebrate its product.
Visitors can use a remote-controlled robot arm to sow watercress -- and pick up the results eight weeks later: a drop of diesel oil that the company's scientists produce from what other people use to garnish their salad.
A tractor can drive two meters (6.6 feet) with one such drop, VW says. It's not much for an agricultural machine -- but it represents a glimmer of hope for a highly mobile society that is eyeing the world's fuel gauge with growing concern.
Engines can handle vegetable oil just as well as gasoline, as the pioneers of machine construction already knew. "It's turned out that diesel engines can run on peanut oil without any difficulty," the ingenious inventor Rudolf Diesel explained in 1912. But Diesel's contemporaries paid little attention to such questions. It was hard for them to imagine that cars would ever be associated with anything like issues of disappearing resources.
Rapeseed and sunflower stalks
The German rapeseed oil industry has undertaken the most sustained effort yet to replace fossil fuels with a botanical product. And over the last decade, what started as an association of independent-minded small businessmen has grown into an economic sector to be taken seriously. In 2005, 1.7 million tons of rapeseed methyl ester, derived from the seeds of the yellow-flowered plant, were used to feed the engines of German cars.
Sometimes biodiesel -- as the product is officially known -- is mixed into conventional fuel; sometimes it's distributed in a pure form. Available at some 2,000 gas stations, the fuel is cheaper than regular gasoline.
Comparable amounts of biodiesel haven't been produced anywhere else in the world. In this sense, the German rapeseed experiment is also indicative of the limits to ecologically clean economic growth. About a million hectares -- roughly a tenth of Germany's agricultural terrain -- are now used to plant rapeseed. Experts believe expansion by a further 1.5 million hectares is possible.
In other words, in the best possible scenario, German soil could yield about 2 million tons of biodiesel every year. Compare that to the 130 million tons of petroleum the German population consumes every year, and it becomes clear that rapeseed will never be able to liberate an industrial society from its dependence on petroleum.
Scarcity isn't the only problem with biodiesel. Fertilizing the fields and processing the harvest is highly energy-intensive, thus eliminating much of the potential for savings.
Moreover, biodiesel's suitability for use with modern engines is limited at best. Its chemical composition complicates efforts to achieve clean combustion and filter emissions. In fact, modern diesel engines with fine-tuned fuel injectors and particle filters are generally not approved for use with rapeseed methyl ester.
Researchers at the Shell Corporation consider rapeseed diesel a "first generation" fuel -- one in which only the seeds or buds of the plant are used. "First of all, the result is not a top-quality fuel," says Wolfgang Warnecke, the man in charge of global fuel development at Shell. "Second, its production competes directly with that of foodstuffs. We're not interested in either of those two things."
Shell is therefore betting mainly on the development of second-generation fuels. These are produced from those parts of plants that were considered agricultural waste until today, such as straw from grain crops or sunflower stalks. "These production processes don't threaten to involve us in any ethical dilemmas," Warnecke says, "and the carbon dioxide balance is virtually neutral."
Driving on alcohol?
One of the first biofuels whose production process is on the verge of proceeding from the first to the second generation is a substance that human beings have used as an intoxicant for millennia -- alcohol.
American automobile pioneers Henry Ford and Charles Kettering (then General Motor's chief researcher) already saw an enormous potential in alcoholic fuel during the 1930s and wanted to power their cars with the fermented products of American farms.
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