Exploit the Waste
Despite all the concerns of the food-energy nexus, there is some cause for optimism. With different innovations, policies, markets and cultural choices that focus on reducing waste and inefficiencies, we can reduce the 10:1 ratio of energy used to energy eaten, as well as mitigate environmental damage.
A first step is to stop using corn kernels for starch-based ethanol, which is the current U.S. practice. Let us use the kernels to feed people and livestock and use only the cellulosic stover (the stalk and leaves of the plant) to make ethanol or synthetic fuels. U.S. energy policy already includes a push for this solution. The Energy Independence and Security Act of 2007 has a renewable fuels standard that mandates that we consume 36 billion gallons of biofuels per year by 2022 and that 16 billion of those gallons come from cellulosic sources. The latter requirement is a rare acknowledgment by politicians in Washington, D.C., that corn might not solve all our energy problems; experts predict we can produce only up to 15 billion gallons a year from corn-based feedstocks grown on available farmland without undercutting our ability to feed ourselves.
The aggressive biofuels rollout, however, pushes the food-based forms online the quickest, with cellulosic forms many years behind because they are more difficult to produce. Nature has designed cellulosic materials over many millennia to not break down. Breaking them down for ethanol means we have to reverse nature, which requires enzymes—code for money; producing enzymes at industrial scales is expensive. Nevertheless, we can overcome the technical hurdles and move more strongly in that direction. Using cellulosic sources instead of food-based sources can help the U.S. energy supply and also free up tens of millions of acres for other food production.
Another step to improve the food-energy equation is to convert agricultural waste products into power. Livestock manure is one rich resource. In the old days, small farms had a mix of animals and a variety of crops in one location; farmers spread manure instead of chemical fertilizer on fields of crops. Today, with large farms that grow just a handful of mega crops and with concentrated animal-feeding operations, that closed-loop practice has been lost. The massive amounts of manure created by large animal operations far exceed any local demand, and it is too expensive to ship cross-country to big farms. The system also creates environmental hotspots such as manure lagoons, which are significant emitters of greenhouse gases and sources of toxic waste. The lagoons are remarkably energy dense, however, and there are many of them; U.S. farms generate more than one billion tons of manure annually.
Anaerobic digesters and micro turbines could convert that manure into enough renewable, low-carbon biogas-fired electricity to displace 2.5 percent of the nation’s power generation while reducing greenhouse gas emissions. This approach would also yield another revenue stream for farmers. Researchers at leading agricultural institutions such as Texas A&M University and Cornell University College of Agricultural and Life Sciences are looking at new ways to incorporate anaerobic digestion of manure into farm operations. Juehnde, a small German village working with Frank Mitloehner of the University of California, Davis, is generating so much biogas for heating and cooking that the town has become independent from the national gas grid. Policy makers could encourage the installation of more digesters and turbines by giving farmers access to low-cost capital, creating incentives such as property-tax breaks for the equipment, offering information and training sessions so that potential users know how to operate the systems, and establishing net metering—a system allowing any electricity generated on-site to reduce farmers’ utility bills.