A car that could run on thin air? On the road by 2016?

That's what Peugot-Citroen says it will be selling: A hybrid car that runs on a combination of gasoline and air. Digital Trends has an explainer on how they think it works, but they admit they were looking at poorly translated press releases. It seems to use hydraulic power to keep the car running and powering it up to speeds of 43 mph.

In recent years, volatile gasoline prices and worries about long-term supply have sent consumers and entrepreneurs alike searching for alternate fuels and alternate energy sources to power their cars.

Companies all over the world are looking for the newest fuel that will power our vehicles in the future, under the belief that at some point, oil will start running out. Here's a look at some wacky, yet plausible, fuel alternatives that are in the process of development right now that could eventually find their way into your car's gas tank:

Thin air

Peugot isn't the first company to think about using air. A small British company is making fuel out of thin air, developing a process that uses air and electricity to manufacture a synthetic fuel that has already powered a Lotus in test drivers.

This one is still a ways away. The company behind the technology, Air Fuel Synthesis, wants to build a full-scale refinery, but that could take 15 years. Still, don't bet against it. Britain's deputy prime minister, Nick Clegg, recently visited AFG's testing facility and came away saying, "I feel I've glimpsed the future."

Chicken guts and pork lard

Mazda is pioneering the use of a synthetic diesel fuel made from leftover animal fats, like chicken guts and pork lard, that are left over from Tyson Foods' slaughtering process. The fuel is going to be tested during an upcoming race at Daytona.

"We're not taking food off the table or feedstock away from animals," James O'Sullivan, president and chief executive of Mazda North American Operations, tells Forbes.com. "This would end up in a landfill."

Think it's far fetched? Alamo and National Rental Car shuttle buses are already using the fuel, as is the U.S. Navy. Yes, animal guts have a role in our national defense.

Perhaps most optimistically, synthetic diesel can be blended with regular diesel and is often drop-in ready for regular diesel pumps at gas stations. And there's more infrastructure in place. Dynamic Fuels opened a $150 million refinery in October 2010 that's capable of processing 1.5 million pounds of "meat remnants" every day, according to Forbes, which can produce 75 million gallons of synthetic diesel every year.

Weeds

As the largest consumer of energy in the government, the Department of Defense has run all sorts of experiments using biofuels in ships, cars and, perhaps most intriguingly, airplanes. The Air Force has powered F-16s with a 50-50 blend of biodiesel derived from camelina plants and regular JP-8 jet fuel.

There has been almost no noticeable difference in jet performance, according to reports, and by 2016, the Air Force is aiming to have its entire domestic fuel use consist of a a 50-50 blend of biofuel and conventional fuel.

Explosive sugars

Technology developed for World War I is nearly a century old. You'd think the latest-and-greatest developments from 1914 had no purpose in today's world. On the contrary, they're actually en vogue.

Researchers at Cal-Berkeley have created a new fuel derived from a process the British used to manufacture explosives during WWI. Fermenting sugars and transforming them into acetone, butanol and ethanol, they've created a biodiesel that could replace gasoline and drastically reduce greenhouse gases.

"It's a much more efficient ... than many of the other products being considered," Harvey Blanch, a Cal-Berkeley professor of chemical engineering, tells The San Francisco Chronicle. "This product is one that may be closest to commercialization."

Wasted spaces

Critics of biofuel development say that production of these fuels use valuable resources like farmland and crops that otherwise would be food. This increases the price of groceries and livestock feed.

Fine, one researcher said. Instead of using farmland, he'll plant biofuel crops in unusual places, like the side of the highway, abandoned assembly plants and fields adjacent to airport runways. Places where farming can't be sustained.

Dennis Pennington, a researcher at Michigan State University, says it would take roughly 200,000 acres to supply enough crops for a processing plant that makes 50 million gallons of biodiesel per year.

In Michigan, he estimates there are 4.5 million acres of "marginal land" that's unable to be farmed. That could translate into 1.125 billion gallons of biodiesel, roughly the same amount the currently flows through the U.S. each year.

If just a fraction of that potential could be tapped, it would "create infrastructure to handle it, crush it and get it into a plant to refine it into a fuel," Pennington tells a public-radio project. "That's job creation and economic development."

Garbage

There's that classic scene toward the end of Back To The Future where Marty McFly and Emmett "Doc" Brown power their DeLorean time machine with the Mr. Fusion Home Energy Reactor, which runs on garbage like the banana peel and a Miller beer can found in the McFly family trash can.

Fusion technology hasn't been perfected since the movie opened in 1985. Garbage as fuel? That's another story.

Coskata, Inc., a company that received investment from General Motors, said it has pioneered a technique that can turn anything from wood chips to municipal trash into ethanol. It already has an ethanol plant running in Madison, Pa.

Sharon Silke Carty contributed to this report. Pete Bigelow is an associate editor at AOL Autos. He can be reached via email at peter.bigelow@teamaol.com and followed on Twitter @PeterCBigelow.