Liquefied Natural Gas
Not to push the cooking theme too hard, but the next alternative fuel that's already on the road is similar to stuff you may have in your kitchen as well. Unlike ethanol or biodiesel, it's not created using something you could eat or drink, but it is something that top chefs insist on cooking with: natural gas.
Natural gas is a fossil fuel that's found between layers of underground rock. It's drilled for, like oil, but there's a lot more of it available here in the United States and it burns cleaner than oil or gasoline. The natural gas that you may use to cook your food and heat your bathwater is natural gas in a very low-pressure form. That keeps this particular fuel in a gaseous state and means that it releases a relatively small amount of energy when it's burned.
However, if you cool natural gas, it becomes liquefied. And when it's liquefied, it becomes much more energy dense. When liquefied natural gas (LNG) is burned, it releases much more energy. So, for example, instead of simply heating up some soup, like low-pressure natural gas is capable of doing quite well, liquefied natural gas can power large equipment, like a truck. And that's just what it's used for -- powering heavy-duty trucks over long distances.