The seven weirdest car fuels

There's no single answer to the fuel of the future, at least certainly not at this time. Part of the solution lies in reclaiming waste streams that now mostly end up in landfills. Some of these -- like diapers -- we don't even want to think about, but it's about time we did. And scientists are on the case, given the strange-but-true examples cited here.

Cellulosic ethanol (made from sugar cane, wood waste or sweet sorghum) is probably the wave of the future, but here are some other ways we can -- and probably will -- make fuel from bio-materials.

The really fast chocolate car

(Photo: Courtesy of University of Warwick)

Is it possible to run a car on chocolate? Well, maybe not wholly on chocolate.

Your Hershey bar won't get you home in an emergency, but a team from the University of Warwick in Britain has built and is track-testing a Formula 3 race car, running on 30% biodiesel derived from chocolate waste.

That's not all; the steering wheel is partly made of carrots, and the mirrors and aerodynamic front wing are formed with potato starch and flax fiber.

According to James Meredith, who heads the project at Warwick, "Anything with a fat in it can be turned into diesel, and that's what we've managed to do." The chocolate is waste from bad batches at Cadbury's in nearby Birmingham. The researchers have managed to keep their fingers out of the chocolate vats. "It's waste, so I assume it's no good to eat," Meredith said.

The coffee grounds car

(Photo: Raychel Deppe / iStockPhoto)

Coffee grinds are an unwanted waste product that fills up landfills and takes a long time to biodegrade. In Europe, however, household food scraps are considered a fuel source.

In Germany and Switzerland, for example, a company collects and then ferments those scraps, producing both a natural gas fuel and compost. So could we actually power cars on biodiesel from coffee grounds? It's a distinct possibility.

You know how coffee can sometimes look (and taste) slightly oily? That's because it contains 10 to 15% of usable oil that can be refined into a biofuel. A study says used cappuccino scraps can offset our imported oil -- as much as 340 million gallons a year from the world's 15 billion pounds of annual coffee production.

"It's a simple two-step process," says Susanta Mohapatra, a University of Nevada, Reno, researcher who is a co-author of the study. Her team raided Starbucks to find the "feedstock" for the coffee fuel. "We can definitely make a big impact on our environment with fuel made out of nature," she said.

The used diaper potential

It was bad enough when scientists figured out how to reclaim paper pulp from used disposable diapers, but they're also saying they can make diesel fuel from them using a pyrolysis process.

A Canadian company called AMEC is in the process of building a pilot plant in Quebec that will process the plastics, resins, fibers, and poop into a predictable mix of gas, oil, and char.

Now adult waste would work just as well, but we don't collect it in handy sealed containers as we do baby waste. The great advantage, says AMEC, is that the raw material is not contaminated with anything else -- it's a rich, if aromatic, source of fuel.

The company hopes to take in 180 million diapers a year -- a quarter of Quebec's output -- to produce 11 million liters of diesel. Considering that diapers can take 100 years to decompose in a landfill, turning them into domestically produced fuel seems a good alternative.

Sawdust, wood chips, nuts?

(Photo: Max Blain / iStockPhoto)

Yes, we will soon be able to make gasoline -- and diesel and jet fuel, too -- from everything from wood chips and sawdust to switchgrass.

Companies around the country are doing this on an experimental basis, using a variety of methods, but the embryonic technology got a huge boost when the Obama administration revised the biofuel standards earlier this month to include a billion gallons of diesel fuel from biomass by 2022.

Biomass gasoline won't be much, if any, cleaner out of the tailpipe than current fuel, but when the lifecycle carbon reductions from growing the "feedstock" is taken into account, it's a big winner.

All Power Labs in Berkeley, California, is competing for the illustrious Auto X Prize with a car that runs on wood chips. "Specifically, we're making carbon-negative, open-source fuel from basically garbage," says team member Tom Price.

The process itself isn't new: During World War II, when gasoline was unobtainable in Europe, there were more than a million cars using gasification technology -- turning coal and wood chips into gas for internal-combustion engines.

Price envisions using waste walnut shells, which normally release the potent greenhouse gas methane. "We can crack the hydrogen out to run an Accord," Price says, "then put the leftovers on the ground to grow more walnuts, which suck more CO2 out of the atmosphere, and the cycle continues."

Styrofoam cups in your tank?

(Photo: Ochelly)

According to Robert Malloy of the University of Massachusetts, used polystyrene coffee cups will make a great fuel component. Polystyrene (used to make disposable foam plates and cups) is very lightweight but also bulky, so it's difficult and expensive to send out for recycling.

But it could make a very effective fuel additive, says an Iowa State study last April. "This study demonstrated that polystyrene-biodiesel blends could be successfully used in diesel engines with minor modifications to the fuel system and appropriate adjustments to engine operating conditions."

According to Song-Charng Kong, a co-author of the Iowa study, polystyrene melts quickly in biodiesel, and fuel that is as much as five percent coffee cups does quite well.

At higher concentrations (they tried up to 20%) it gets too thick. Right now emissions are a problem, but they're working on it.

Turkeys: Lots of guts, plenty of glory

(Photo: John Cairns / iStockPhoto)

Americans consume an estimated 45 million turkeys on Thanksgiving, raising the impolite question: What happens to all the turkey guts?

A bunch of entrepreneurs in Carthage, Missouri, not only asked that question, they answered it, too, by opening a plant that could process turkey waste (including feathers, using up everything but the gobble) into a fuel oil that could be processed into diesel, gasoline, or jet fuel.

The process, known as thermo-depolymerization (TDP), is well known, and it works, The turkeys' private parts break down under very high heat and pressure, yielding natural gas, fuel oil and minerals. The company says it could also produce light crude from hog and chicken waste -- or onion byproducts and Parmesan cheese rinds, for that matter.

The big problem, however, is that the plant stinks, and it's close to a residential area, prompting withering complaints. The company, Changing World Technologies, may seek greener pastures.

Cow power: High-octane gas

(Photo: Gloria Dawson / The Daily Green)

Wow, according to the United Nations, the livestock industry (including the growing of all the cattle feed, the transportation to market, and energy for factory-farm operations) is responsible for 18% of global warming emissions -- more than transportation worldwide.

And it will get worse: Current projections show meat production more than doubling to 469 million tons in 2050.

One of the main culprits is methane, a global warming gas that is 23 times more potent than carbon dioxide. The world has 1.5 billion cows, and they produce methane out of both ends (belching more than flatulence). An estimated two thirds of the planet's ammonia comes from cows, too. In New Zealand, livestock accounts for 34% of greenhouse gas emissions.

Partly because they're eating grain instead of the grass nature intended, cows can produce 50 to 130 gallons of methane every day. Suppose we could use that as a fuel, since methane burns very well. Eureka!

Dairy farms such as Blue Spruce Farm in Vermont are putting their cow waste in anaerobic (no oxygen) digesters for three weeks, producing methane, and then burning it in generators to produce electricity. This "cow power" is being sold to a nearby college, and it can also be fed back into the grid. The process also generates useful fertilizer.

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Reprinted with permission of Hearst Communications, Inc

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