The term biofuel only recently crept into our everyday language, but man spent hundreds of thousands of years on the verge of developing biofuel.
Biofuels are created by converting biomass, or matter once plant or animal, into a fuel, something that stores potential energy for subsequent release as heat or chemical energy. Wood was the first biofuel, and remains the world’s most widely used. Charcoal and animal dung are also traditional biofuels.
Heat energy can be constrained to create mechanical energy. A coal-fired, or biofueled steam locomotive is perhaps the archetypal example of the conversion of biomass into mechanical energy.
The contemporary concept of biofuel has evolved from its humble kindling and dung pile beginnings, however. We now think of biofuel in terms of sustainability. At least 80 percent of a biofuel must consist of renewable materials. Science has also introduced the concept of primary and secondary biofuels.
Peat, dung and wood are primary biofuels. They store and can release energy, most often heat, directly from their unprocessed state.
Secondary biofuels are the products of processing biomass to create a different solid, a liquid or gas. Charcoal, a wood product, was the first secondary biofuel; grillers the world over pay homage to secondary biofuel with every tasty steak they plate. Technology has rendered secondary biofuels increasingly versatile, however. Almost every car and truck in the United States and Europe runs on a blend of fuels that includes ethanol or biodiesel, two common, renewable secondary biofuels. Ethanol is a byproduct of plants with high sugar or starch profiles, and biodiesel is a combination of plant oil or animal fats with alcohol.
Although still quite nascent, current research includes intensive studies of algae and cyanobacteria as alternate renewable biomass materials from which to produce biofuel.