What are the environmental pros and cons of switching to plant-based “bio-fuels” to reduce our reliance on oil?
—Jim Dand, Somerville, MA
There are many eco-benefits to replacing oil with bio-fuels like ethanol and biodiesel. For one, since such fuels are derived from agricultural crops, they are inherently renewable—a°nd our own farmers typically produce them domestically, reducing our dependence on unstable foreign sources of oil. Additionally, ethanol and biodiesel emit less particulate pollution than traditional petroleum-based gasoline and diesel fuels. They also do not contribute to global warming, since they only emit back to the environment the carbon dioxide (CO2) that their source plants absorbed out of the atmosphere in the first place.
And unlike other forms of renewable energy (like hydrogen, solar or wind), biofuels are easy for people and businesses to transition to without special apparatus or a change in vehicle or home heating infrastructure—you can just fill your existing car, truck or home oil tank with it. Those looking to replace gasoline with ethanol in their car, however, must have a “flex-fuel” model that can run on either fuel. Otherwise, most regular diesel engines can handle biodiesel as readily as regular diesel.
Despite the upsides, however, experts point out that biofuels are far from a cure for our addiction to petroleum. A wholesale societal shift from gasoline to biofuels, given the number of gas-only cars already on the road and the lack of ethanol or biodiesel pumps at existing filling stations, would take some time.
Another major hurdle for widespread adoption of biofuels is the challenge of growing enough crops to meet demand, something skeptics say might well require converting just about all of the world’s remaining forests and open spaces over to agricultural land. “Replacing only five percent of the nation’s diesel consumption with biodiesel would require diverting approximately 60 percent of today’s soy crops to biodiesel production,” says Matthew Brown, an energy consultant and former energy program director at the National Conference of State Legislatures. “That’s bad news for tofu lovers.”
Another dark cloud looming over biofuels is whether producing them actually requires more energy than they can generate. After factoring in the energy needed to grow crops and then convert them into biofuels, Cornell University researcher David Pimental concludes that the numbers just don’t add up. His 2005 study found that producing ethanol from corn required 29 percent more energy than the end product itself is capable of generating. He found similarly troubling numbers in making biodiesel from soybeans. “There is just no energy benefit to using plant biomass for liquid fuel,” says Pimentel.
There is no one quick-fix for weaning ourselves off of fossil fuels and the future will likely see a combination of sources—from wind and ocean currents to hydrogen, solar and, yes, some use of biofuels—powering our energy needs. The “elephant in the living room,” however, that is often ignored when considering energy options is the hard reality that we must reduce our consumption, not just replace it with something else. Indeed, conservation is probably the largest single “alternative fuel” available to us.