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.
The temple of car worship offers its visitors cinemas, museums and educational installations. But the most interesting exhibition piece is probably also the most significant for the automobile's future. It's a transparent plastic case. Inside the case is a vegetable garden.
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.
Roughly 100 years later, though, there are half as many cars in the world as there were human beings alive back then. Some 800 million motor vehicles make up a vast army of gas-guzzlers. Every day motor vehicles consume about 10 million tons of oil -- more than half of what is produced worldwide -- on a daily basis. Finding a way to power these vehicles on a renewable fuel will be one of the Herculean tasks of the new millennium. Peanut oil simply won't be enough.
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.
Around 1860, Nikolaus August Otto created a prototype of an engine fueled with different types of spirits available for consumer purchase. One was ethyl alcohol, then widely used as lamp fuel.
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.
Part II: Prophets of oil addiction
Francis Garvan, president of the Chemical Foundation at the time, wrote a fierce appeal for alcoholic fuel instead of oil from abroad: "They say we have foreign oil," Garvan explained during a conference in Ford's hometown of Dearborn near Detroit in 1936. "It is in Venezuela ... It is out in the East, in Persia and it is in Russia. Do you think that is much defense for your children?"
But the alcohol lobby failed to prevail. New oil fields were discovered too quickly -- especially in Arab lands. Fossil fuels turned out to be the cheaper option -- and Western industrial nations marched steadfastly into total dependence on imports.
Only one country followed a path of its own and opted for alcohol: Brazil. Today the South American country covers about 40 percent of its fuel needs with bioethanol, a form of alcohol.
The tropical climate in Brazil allows for growing vast amounts of sugar cane -- a raw material used in the production of ethanol. Yet what may sound like a blessing isn't necessarily one for the local environment -- millions of hectares of rainforest have been cleared for car fuel plantations.
In Europe and North America, ethanol is obtained mainly from cereals such as wheat, rye or corn. In Germany, companies such as Südzucker have started running alcohol refineries. All of these companies are still working with first-generation production methods. Their output would never be sufficient to adequately replace gasoline. Researchers have only been working on efficient methods for converting straw and wood to ethanol for a few years.
Factories where these methods can be put into practice are still in the research stage and are being developed partly with the support of the large oil corporations. Shell has invested in the Canadian ethanol producer Iogen, one of the pioneers of this young business sector.
Politicians and engineers from all industrial nations are now equally intoxicated by the idea of powering cars with alcohol that is mainly produced from waste products. In fact, Sweden even sees bioethanol as the key to its efforts to completely liberate itself from petroleum dependence by 2020.
The US government also considers bioethanol to be one of the fuels of the future, one that will allow for the definitive transition to energy autonomy. President George W. Bush recently announced: "We want people to drive with fuel that grows in America."
One of the great advantages of alcohol is its similarity to gasoline. Conventional fuel can contain up to 5 percent alcohol without creating a need to modify engines.
In Europe, mixtures of alcohol and conventional fuel are available with an alcohol content of up to 85 percent. Ford and the Swedish car manufacturers Volvo and Saab are already offering vehicles whose engines run on the new fuel, known as E85. The changes made to the engine control system are minimal; the price increase is no higher than a few hundred euros.
In South America cars are already running on pure ethanol. However, the greater the alcohol content in the tank, the more the engine's fuel consumption rises -- because alcohol contains only about two-thirds as much energy as gasoline.
So far, German ethanol producers remain weak contenders in the global fuel business. While Brazil is already producing 10 million tons of bioethanol per year, the three production plants in Germany produce only about half a million tons. "The great challenge will be producing a genuinely viable substitute," says Shell researcher Wolfgang Lüke.
But what is the true potential of the alcoholic fuel that so many are pinning their hopes on? According to calculations by the Agency of Renewable Resources (FNR), the German Ministry of Agriculture's unit specializing in biofuel, 2,500 liters of ethanol can be obtained from the grain harvest of one hectare (2.5 acres) of German agricultural terrain. Because one liter of the fuel replaces 0.66 liters of conventional gasoline, production on that one hectare represents real substitution for only 1,650 liters.
Oil is solar energy, too
Another new technology, which is still being developed, is far more promising. It's called "SunDiesel" and is currently being tested in Freiberg in the German state of Saxony.
There, the visionary Bodo Wolf -- who was trained as a coal miner and later became an engineer -- has developed a method that allows for high-speed replication of the process by which fossil fuels are formed from wood and other organic substances.
The key insight that allowed him to develop his method in East Germany before the fall of the Berlin Wall is contained in a simple truth: "Oil, gas and coal -- they're all solar energy."
All the fossil fuels central to the industrial age are the product of prehistoric vegetable and animal life that disappeared under the earth before it could rot. Forests became coal; dry lagoons full of algae and water animals became oil and gas fields. Exposed to enormous pressure and high temperatures, the former organisms were transformed into the solid, fluid and gaseous energy sources of today.
Part III: Learning from nature
Wolf has developed a method that replicates this very process and speeds it up dramatically. Wolf's patented "Carbo-V method" accomplishes in a few hours what nature took millennia to achieve: wood, straw and every other form of dehydrated organic matter is converted into a synthetic gas in a system of burners and catalysts. Diesel fuel is then extracted from this gas by means of a Fischer-Tropsch reactor, a piece of equipment already used to liquefy coal and natural gas.
The company Wolf founded is called Choren. The first three letters of the name stand for carbon (C), hydrogen (H) and oxygen (O) -- the building blocks of organic life and of every conventional fuel; the last three letters of the name are short for "renewable."
The founder of Choren is now retired, but a host of powerful companies has staked a claim to his legacy. Daimler Chrysler and Volkswagen have been Choren's development partners for three years. And Shell invested in the company last year.
The expectations are high, even though Freiberg's diesel producers are still a long way from going commercial. So far, only a small research plant has been set up. Next year -- much later than originally planned -- a second, larger plant is scheduled to go into operation; it will produce 15,000 tons of SunDiesel every year. Eventually, a major refinery will be built in the town of Lubmin in the eastern German state of Mecklenburg-Western Pomerania to produce an annual output of 200,000 tons.
The most dangerous opponent on the path to that goal may well turn out to be the German government. The rising production of biofuel already has cash-strapped fiscal authorities looking for new ways to tax it. German Finance Minister Peter Steinbrück of the Social Democrat Party (SPD) has already announced that biofuels will soon be taxed just like gasoline. The extra costs that would result might mean that only the cheap option of rapeseed oil survives. More promising methods that are still in development may have to be abandoned before they reach the market.
Nevertheless, the European automobile industry has tremendous hopes for SunDiesel. Because they consume so little fuel, diesel engines are one of the trump cards of the industry -- despite the blemish of being associated with worse emissions. The problem of soot particles has been partly solved thanks to new particle filtering techniques. What remains is the unusually high level of nitrous oxide emissions, a problem that can only be solved with new investment into technologies like urea-based catalytic converters.
The new fuel might offer a solution: SunDiesel is cleaner than conventional diesel. It's non-toxic and free of aromatics. Substituting SunDiesel for regular fuel would lead to a strong reduction in emission levels without requiring any additional processing of the emissions.
What is more, synthetic fuels like the one developed by Choren, which are also known as BtL ("biomass to liquid") promise marvellous efficiency -- even if they haven't yet been commercially tested. German government experts with the FNR estimate that an annual output of 4,000 liters (1,057 gallons) per hectare could be achieved with SunDiesel -- three times as much as with rapeseed oil and about one-and-a-half times as much as with ethanol.
But still more can be gotten out of biomass. As a raw material, wood is a first-class energy supplier -- especially when it isn't used to power cars, but rather to produce electricity and heat.
Thomas Nussbauer, an expert on resources at the Swiss Federal Institute of Technology in Zürich, flatly declares tree-based biofuel unsuitable for use in road transportation. In an article for the Holz-Zentralblatt journal for the timber and forestry industry, he makes a plea for putting the remains of trees into furnaces rather than into fuel tanks. According to Nussbauer, wood provides heat as efficiently as fossil fuels, but yields only three-fourths of their output when used as engine fuel.
Michael Deutmeyer, who is responsible for biomass management at Choren, doesn't doubt the validity of Nussbauer's calculation, but argues that it misses the main point. Deutmeyer argues that there are already many alternatives to fossil fuel energy sources in the areas of heat and electricity production: "Geothermal and solar energy production, improved insulation, as well as wind and water power represent a broad variety of techniques that can already be put to use," he says. "But when it comes to transportation, there is still no viable alternative to fossil fuel energy sources." For better or for worse, the car still depends on petroleum. Attempts to power cars with electricity have effectively failed.
Part IV: Cars don't need liquid fuel
Nor do the current improvements in battery technology for hybrid vehicles promise to make electric car engines suitable for serial production anytime soon. A full gasoline tank, which can power an engine for hundreds of kilometers and can be refilled in a matter of minutes, is still far superior to every alternative developed so far.
Natural gas, like from cows
Still, the contents of the tank don't need to be liquid. So far, the best alternative to fossil fuels like gasoline and diesel has come in the form of gas, not liquid. It, too, comes from plouwing the fields, and it's already being produced by a technique as simple as it is well-proven.
According to calculations by the FNR experts, methanol from fermented biomass has the greatest potential. An annual 3,560 kilograms (7,849 pounds) of methanol can be obtained from one hectare. That would be enough to replace 5,000 liters (1,320 gallons) of gasoline -- the best result yet.
On the surface, the technique resembles that used in ethanol production; both are much simpler than the highly complex techniques involved in BtL production. The harvest doesn't have to be dehydrated, but automatically turns into the desired fuel after it's placed into a large vat filled with moist sludge.
The designers of the technique were inspired by the digestive system of cows and other herbivores -- and by the natural cycle of growth, ingestion, excretion and fertilization. "Biogas" can be developed from a wide variety of plant types and this diversity is also beneficial to the soil. The process also results in its own fertilizer -- the waste products can be used as fertilizer just like dung.
So far, the biogas sector has concentrated mainly on electricity production. The gas obtained in the production process drives generators that create energy for the power grid. The average output is far lower than that of windmills or solar panels, in terms of space needed for electricity production. But energy farms have an advantage that the administrators of the electricity grid value highly: They provide energy constantly -- even at night or when the wind isn't blowing.
Inside the small power plants, the biomethanol does exactly what it would do inside a car: It powers engines. It's also perfectly suited for fuelling natural-gas-powered cars.
Oil Rigs to Plowshares
But the industry has been slow to adapt the fuel for transportation. Biogas fuelling stations have opened only in scattered locations -- in Germany and Sweden, for example. The problem is a lack of customers. Even the use of natural gas as engine fuel is hardly advancing. For years, the gas producers and the producers of natural-gas-powered cars -- Opel, Volvo and FIAT are the leading manufacturers in the sector -- have been fighting for acceptance, but with little success. Their projects have been stalled due to the expenses involved in making the necessary changes to existing cars and to transportation infrastructure.
A natural gas fuelling station complete with the required pressurized storage unit costs about €200,000 ($254,602) -- about four times as much as a gasoline or diesel station. The car producers in the sector charge surcharges of between €2,000 ($2,545) and €4,000 ($5,090) for cars with engines equipped to handle natural gas, partly because of the additional cost of equipping a car with a pressurized tank.
What is more, only a few of the natural-gas-powered cars currently available on the market can drive an acceptable distance before they need to be refuelled. Installing a sufficient number of pressurized gas containers is not yet technically feasible in most cars. The result is that the state-subsidized -- and therefore extremely cheap -- alternative fuel has yet to make the breakthrough into the mainstream. Barely 30,000 natural-gas-powered cars are in use in Germany, where some 650 fuelling stations have been set up -- perhaps somewhat too optimistically.
Experts employed by large oil corporations also disagree about the alternative fuel's chances of success. Aral, a subsidiary of BP, has consistently sponsored the expansion of the network of fuelling stations -- particularly due to the tremendous regenerative potential of biogas. The experts at Shell, on the other hand, believe natural gas will never be more than a niche market (for companies with their own fleets of vehicles, for example) and prefer to focus on the conversion of natural gas to liquid fuel.
"The greatest mistakes we can make during the search for alternatives are overhasty experiments with infrastructure," Shell researcher Wolfgang Lüke warns. In his view, the only alternative fuels with potential are the ones that can be mixed with conventional fuels. Ethanol and SunDiesel meet this criterion.
Lüke predicts that the liquids that will provide energy in the post fossil fuel age will be mixed with conventional fuels in gradually increasing quantities, ending the era of petroleum drop by drop -- a comfortably slow process that has already begun and that consumers hardly notice, aside from the occasional ineffectual political debate.
It seems advisable, on the other hand, not to overestimate the speed at which this development is taking place. Sparsely populated countries such as Sweden, which is striving for independence from oil, or the US, an oil-junkie well aware of the problems involved in oil dependence, do dispose of agricultural areas large enough to provide a substantial chunk of their industry with biomass. But in central Europe, producing sufficient amounts of car fuel on an organic basis isn't even remotely feasible.
Part V: Vegetation is more powerful than oil (potentially)
According to a prediction by the FNR, some 3.5 million hectares of German agricultural terrain will be available for biomass production in 2020. If one takes an optimistic view of future technological development, this terrain could provide about one-fourth of the vehicle fuel consumed in Germany.
Globally, however, "the potential of biomass is enormous," says FNR expert Birger Kerckow. And Konrad Scheffer, a professor at the Institute of Crop Science at the University of Kassel in western Germany, claims that the energy content of the vegetation that is constantly reproducing itself on the Earth's surface exceeds humanity's current energy needs by a factor of between eight and 10. In the scenarios developed by the agricultural industry, plowshares will replace oil drills. Former Agricultural Minister Renate Künast, a member of Germany's Green Party, has already dubbed farmers the "oil sheikhs of tomorrow."
Hydrogen, the last frontier
The magic gas that some car companies like to evoke as the future elixir of guiltless mobility isn't much talked about today -- hydrogen.
Engineers long considered the lightest of the elements in the periodic table the universal energy source of the post fossil fuel age. Produced from water by solar or wind energy, the explosive gas was to be used as an unlimited energy source -- perfectly clean and infinitely reproducible.
Car companies invested billions in the development of prototypes. Vans and cars with combustion units that transform hydrogen into energy highly efficiently and without producing significant emissions can still be found in many places.
Combustion engines can be powered with hydrogen too. BMW developed a hydrogen-fueled 12-cylinder race car that broke the 300 km/h (186 mph) barrier in an entertaining "green" car race. Mercedes even planned to begin selling cars with hydrogen combustion units by as early as 2004.
But no one is talking about the new technology anymore. Daimler Chrysler is now aiming for 2015 -- and will probably have to revise this goal as well. There are plenty of cars that could run on hydrogen -- what's missing is the hydrogen itself.
Nowhere in the world can one even find the beginnings of a project for producing the ecologically clean gas on an industrial scale. Even Shell, one of the most open-minded companies in the petroleum business, is tentative when it comes to making statements on hydrogen fuel: "Hydrogen could be the ultimate fuel," reads the caption on one of the images that research and development director Warnecke likes to hand out.
According to Warnecke, one of the greatest obstacles is hydrogen's incompatibility with existing fuels: "Ethanol and BtL can just be mixed in with conventional fuel. Hydrogen requires a shift to a completely new infrastructure."
And this infrastructure would be many times more complicated and costly than that required by natural-gas-powered cars. Hydrogen needs to either be cooled down to minus 253 degrees Celsius (minus 423 degrees Fahrenheit) or pressurized at 700 bar (three times the level of pressurization for natural gas) before a car can use the fuel to drive a reasonable distance. The existing petroleum-oriented infrastructure is therefore completely inadequate.
Apart from economic obstacles, even experts without close ties to the oil industry are also sceptical about the environmental benefits of hydrogen. The ecologically "clean" production of hydrogen requires a tremendous surplus of electricity from ecologically viable sources. Such a surplus exists only in a few locations, such as the geothermal paradise Iceland (where thermal heat can be used to produce energy) or Paraguay (where water power is plentiful).
The Wuppertal Institute, a respected German institute that studies the environment, climate and energy, examined the risks and opportunities of a forced transition to a hydrogen economy. The sobering conclusion was that such a transition "won't make ecological sense anytime during the next 30 to 40 years." It would be much more effective to introduce the energy produced from ecologically viable sources directly into the electricity grid, rather than to use it to produce hydrogen.
If, however, the clean and large-scale production of hydrogen did begin in the middle of the 21st century, then the gas wouldn't likely end up in the fuel tanks of hydrogen-powered cars.
The producers of botanical-based fuels would likely turn out to be eager purchasers of hydrogen. The production of BtL-diesel is suffering from an acute lack of hydrogen. Introducing the highly reactive substance into the Choren production process could double the total output of BtL-diesel plants.
The result would be a fully sustainable production chain, one that follows the example of millennia of natural history. Hydrogen is an element that likes to bond with other elements. Only when it is combined with carbon does the basic building block of organic life result -- and with it the energy resources petroleum and natural gas.
"Nowhere in nature does hydrogen appear in a pure form," says Choren-founder Wolf. "Why should it do so in industry?"