The term “biofuels” makes headlines daily, but the concept is not new—people have been deriving energy from biomass for millennia, for instance through burning wood, peat, corn stalks, and other crop residue for heat and cooking.
Currently, the world relies primarily on fossil fuels as the main source of energy—but burning them has had a profoundly negative impact on our environment (see Chapters 19–22 for more). And with increasing demand for energy, continued dependence on these nonrenewable fuels is no longer a viable option. Communities are experimenting with ways to produce electricity without fossil fuels (see Chapter 24) and with sustainable alternatives to power motor vehicles.
Biofuels are derived from material from living or recently living organisms (biomass) or their by-products. Fuels derived from biomass are considered renewable since the raw materials can be naturally replenished relatively quickly. Biofuels also have the advantage of being locally produced and thus they reduce a nation’s dependence on other countries for energy.
But biofuels are not a simple solution to our energy problems. For one, their raw materials or feedstocks—crops, animal waste, and wood products—require resources to grow. Furthermore, to function as a fuel, these materials must be converted into another form, a process that uses energy.
Today, there is a massive effort to render that process more sustainable. Biofuels currently provide about 4% of the energy used in the United States and Canada (more than any other type of renewable resource other than hydroelectric). According to the U.S. Department of Energy, global biofuel supply and demand is expected to grow more than sixfold, from 45 billion to 315 billion litres over the next two decades.
But, as Tilman was about to learn, replacing fossil fuels—especially petroleum—is no easy task.
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