3 Gross Green Fuels That are Powering Vehicles Now

Corn, soybeans and cooking oil are ingredients that can go between our kitchens and our cars, since they can be used for fuel. They're not the only sources, though, as recent headlines have been made by far more unusual - and sometimes icky - substances powering our vehicles. Here are a few:

The least disagreeable ingredient on this list is beer waste, which the Sierra Nevada Brewing will use to power the company's trucks. The waste, which is made of yeast, will be put through an on-site ethanol machine for fermentation, and then added to gasoline to be used in the brewer's fleet of biodiesel trucks. Any surplus fuel may even be given to the company's employees. Sierra Nevada generates 1.6 million gallons of beer dregs each year.

Next, a British town has introduced a garbage can that is run by garbage. It won't work quite like the beer trucks - the garbage collected for the truck is actually incinerated, which generates electricity for the plug-in hybrid garbage truck. It takes between six and eight hours for the truck to fully charge. Hybrids are a great choice for garbage trucks because they are slow moving and spend much of their time idling (though incineration, unfortunately, has its environmental downsides).

Finally, there's the fuel that lives up to the headline of this story - some city buses in Norway are now fueled by human waste. Biomethane from two sewage treatment plants in Oslo will be captured and used as fuel for the buses, cutting the carbon footprint of both the plants and the bus fleet. It's not quite as gross as it sounds - microorganisms will break down the waste before it's used in the buses, so no one's health is at stake. The gas is an economic draw as well as an environmental one - each liter is 50 cents cheaper than diesel.