It might surprise you to know that only a quarter of the energy a car engine burns actually gets converted to motion. And even with technological advances, this paltry figure seems unlikely to improve much, until now. The New York Times recently reported that the Energy Department is financing research programs by automotive manufacturers in the field of thermoelectric-based energy recovery. If it proves useful, such thermoelectric generators could improve a vehicle’s fuel efficiency by up to 10 percent.

In the meantime, there’s always Four Loko. Earlier this year, the Associated Press reported that truckloads of high-alcohol caffeinated malt beverages would be recycled into ethanol and other products. So instead of throwing away all the unopened Four Lokos and drinks like them that had been banned, wholesalers from Virginia, North Carolina, Maryland and other states along the Eastern seaboard are sending cases to MXI Environmental Services in Abingdon, Virginia. MXI will recycle the drink, which has been described by some as tasting like rocket fuel, into car fuel.

Brian Potter, vice president of operations at MXI's facility in Abingdon, Va., told the AP that a few hundred truckloads of the drinks would be coming to the plant. Each truck holds 2,000 cases of the 23.5-ounce cans. "We're equipped to process four truckloads a day, and we're at full capacity," he said. "There are about 30 different products involved, and we've only seen a couple of them at this point. It could go on for several months." He also said that MXI’s ethanol-recycling competitors were taking the drinks.

The company also recycles the drinks’ water, cardboard packaging and shipping pallets, then sells the aluminum cans to a recycler.  All in all, it sounds like a pretty great solution. Got any more good news stories about recycling, or other ideas for increasing fuel efficiency beyond Four Loko and thermoelectric generators? Let us know.

(A portion of this story was previously published as “Turning Four Loko into Ethanol” on The Responsibility Project on 1/26/11)