Biofuels -- the word seems magical. It brings to mind singing birds, clear blue skies and global happiness. Somehow, we can turn plants and other organic material into something to power our cars and save the planet at the same time.

But it's not magic at all. In this article we're going to discuss what biofuels are, what they are not, and how they're harnessed from biomass (that is, organic material from plants and animals). We'll also talk about the promises and tradeoffs of the major types of biofuels.

First of all, what are biofuels? According to the U.S. Department of Energy (DOE), they are renewable solid, gas or liquid fuels developed from plants and organic material that can be processed to produced fuel to power our cars and SUVs, heat our living spaces or operate machinery. Renewable in this sense means we get the resources to make the fuel from something that we can replenish easily in a reasonably short period of time -- like plants. While oil and natural gas also come from plants, these aren’t renewable because it would take millions of years to refresh our supply of these fossil fuels.

For decades, homeowners have had the option of using solid fuel like wood or corn pellets -- though lately, it has become more popular way to help offset the wild swings in fuel oil prices. For transportation purposes, by far the most common biofuels in use today are ethanol (a form of alcohol produced from starch or sugar) and biodiesel (a fuel based on oil, fats or greases).

Tracking biofuel production is not yet an exact science due to the many methods used to produce it, but data for the overall production and consumption of biodiesel and ethanol is reliable. After dropping a bit in the mid-1990s, ethanol production in the United States is at an all-time high. Biodiesel production in the United States skyrocketed from 2 million gallons in 2002 to 700 million gallons in 2008, according to the National Biodiesel Board, an American industrial trade association.

Sure, alternative fuels can be very useful, but how do they actually convert biomass into something usable?