Biofuel Production
A field full of rape crops. As well as causing hell for hayfever sufferers, rape can be turned into biofuel. Photo Courtesy of Neil
Most biofuels come from the same place as food: from crops grown on farmland. They are commonly ground up and dissolved in a solvent to extract the relevant desired material.
Let's take the example of ethanol production from sugar cane. Once we have extracted the sugar from the crop, we can use chemical processes (esterification) to turn it into ethanol.
We could just burn the crop itself, but we can increase the energy density by these processes (so burning a smaller amount of biofuel releases more energy than the equivalent mass of crop).
A liquid is also easier to transport, it is more easily used in vehicles and it can be regulated more easily.
Biofuel Problems
Photo courtesy of Lee Jordan
There has been a lot of controversy over the recent push for biofuels, especially in America. The problem is that crops used for this purpose usually take away land for crops used for food.
Increasing biofuel use is likely to exacerbate any food shortages. It is often more economical for farmers to grow crops for this purpose also, as there is funding available for growers.
Not only that, but they do not eliminate the problem of carbon emissions. Granted, burning biofuels emits far less carbon dioxide than oil, but it still emits, and the amount emitted is proportional to the amount burnt. It is only a net gain if biofuels are used in place of fossil fuels, rather than in place of clean renewables.