Biofuels Gain Energy BalanceIt seems like a paradox, but it takes a lot of energy to make the fuel we need to move the cars, buses, trains, trucks and planes in the global transportation chain. The difference between how much energy it takes to produce a fuel and how much energy the final fuel product contains is known as a fuel’s “energy balance” and it is one of the most critical, and controversial, factors when looking at the potential for biofuels to replace fossil fuels.
“In the big picture, no energy is ever created or destroyed but when we look at our energy systems we have to account for the energy we lose to the environment when we are processing and transporting fuel from one state to another,” says Don O’Connor, president of Vancouver-based energy consultants S&T Squared Consultants Inc. “Each fuel has a different energy balance and it can be very difficult to calculate because there’s so much data that needs to be considered.” Comparing the energy balance of gasoline and diesel with their biofuel counterparts, ethanol and biodiesel, has been fraught with conflict in recent years. Contradictory studies have been used to argue for or against the value of biofuels, and particularly ethanol produced from crops such as corn, in reducing the environmental impact of motor vehicles.
Reliable figures are emerging, however, that show biofuels can be significantly more efficient and result in lower greenhouse gas emissions than liquid fossil fuels. It is generally accepted that it takes 0.3 units of energy to produce one unit of energy in gasoline from conventional crude oil. Diesel fuel is slightly more efficient at 0.25 units for every unit of energy in the final product. The energy requirement doubles to 0.6 for gasoline derived from more energy-intensive synthetic crude from oilsands operations. Biofuels are considered to have less favourable energy balance numbers, with ethanol requiring 0.67 units of energy to produce from corn and 0.75 from wheat while biodiesel produced from canola and soybeans require 0.25 and 0.27 energy units respectively. However, these energy inputs do not include the energy contained in the fuels themselves. When fossil energy in fuels themselves is taken into account, as most energy balance studies do, gasoline and diesel have negative energy balances, while biofuels have positive energy balance.
Looking forward, biofuels are expected to fuel up a greater share of North America’s vehicles, and work towards the next generation of ethanol and biodiesel products promises a huge leap ahead of fossil fuels when it comes to energy balance and greenhouse gas emissions. Using the new Greenhouse gases, Regulated Emissions and Energy use in Transportation (GREET) model he developed to evaluate fuel performance, leading biofuels researcher Michael Wang from the U.S. Department of Energy’s Argonne National Laboratory says, fuel from plants is more efficient than previously thought since it comes directly from pollution-free sunlight. He also argues that shifting ethanol production towards using cellulose-rich biomass like grass, wood, straw and agricultural waste products could yield as much as a nine-fold return on energy used to produce it. “Farming cellulosic biomass is not as energy intensive as corn farming,” Wang explains. “There is less chemical and energy input and there’s even the possibility of using lignen in the plant matter to power the ethanol production instead of fossil fuels.” O’Connor agrees that biofuels from non-food crop sources will likely become more important but also warns that production processes are still being developed and many questions about the energy and pollution outputs are still unanswered. He adds that shifting biofuels in western Canada towards more appropriate crops such as softer, starch-filled wheat as opposed to protein-rich bread wheat, can easily and quickly boost production. “We need to be careful about rushing away from the first-generation biofuels because there is very little evidence yet that the next generation will be that much better,” he says.
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