The ever rising costs of oil and gas have propelled people into searching for the one, true alternative fuel. Biodiesel, in the stern chemistry sense, is formed from alcohol esters that are processed from the oils of veggies like soybeans, mustard seeds and rapeseeds. Fat is also sometimes used.
You mix the plant oil with the alcohol compound like methanol or ethanol with a catalyst that is hydroxide-based like sodium hydroxide or potassium hydroxide. Though there are a few alternative sources of fuels that are rising in the market, biodiesel is winning votes and making quite a following. This could of course be because it's so flexible.