Another waste stream that can save food energy is carbon dioxide from smokestacks at coal plants. It can be used to grow algae for human food, animal feed and fuel, thereby avoiding some traditional energy inputs for agricultural production. Some people already eat algae directly for nutritional reasons, and some national restaurant chains use them as a stiffening ingredient. Algal lipids can also be converted into biodiesel, providing a low-carbon, domestic, renewable fuel that is made from something other than food-based feedstock. The remainder of the algal biomass is typically made up of proteins and carbohydrates, which might displace corn-based feed for animals, making more corn available for food and thereby contributing positively to the food-energy nexus. Some algae grow well in brackish water or saltwater, too, eliminating demand for freshwater. Private industry (through a variety of start-ups such as Solazyme), national labs such as the National Renewable Energy Laboratory, and universities such as the University of Texas at Austin and the University of California, San Diego, all have active testing and pilot programs. Although algal solutions seem to be decades away from large-scale implementation, their promise warrants additional research, so policy makers should continue funding development.
More Crop per Drop
Simply implementing innovative agricultural techniques that have already been perfected in pilot programs on a much wider scale could significantly reduce the 10:1 energy-food ratio. For example, drip irrigation provides more crop per drop, sparing freshwater and the energy needed to pump it. The conventional approach—the center-pivot sprinklers that create alienlike green crop circles in the middle of brown deserts (easily visible when flying overhead)—is extremely wasteful, spraying water into the air where a major fraction evaporates. Droplets that do land on crops are likely to hit the leaves and stalks instead of the roots, causing more evaporation loss. In a typical drip-irrigation setup, long sections of narrow tubing laid at the bottom of plants sown in a row deliver water directly to the roots. Researchers at Iowa State University estimate that corn farmers in that state would use 40 percent less water and lower their energy bills by 15 percent with drip irrigation. Half a dozen large farm suppliers now offer the systems, which, if used widely, could save thousands of megawatt-hours of electricity nationwide every year. Incentives to switch to drip irrigation, combined with penalties for wasted water, might hasten adoption.
No-till agriculture is another promising approach. It reduces the disturbance of soils by using special planting equipment that places seeds into untilled soil through narrow surface slots rather than the blunt approach of turning the soil. Disturbing the soil less reduces labor, irrigation, energy, erosion and carbon emissions. Argentina is the world leader; more than half the farms there deploy this advanced technique. Training for farmers about the advantages of no-till can be implemented through agricultural extension services nationwide.
Laser-leveled fields can minimize erosion, irrigation and fertilizer runoff. Most fields have a gradual slope, which causes unequal water distribution and uneven collection of runoff. Rather than risking one portion getting less water than it needs, farmers often overfill the entire field, with the excess spilling over into local waterways. By making fields level, farmers waste less energy pumping water, and less fertilizer is needed because less runs off.
The advent of GPS-enabled tractors, combines and other machinery—today a standard feature offered by manufacturers such as John Deere—has introduced the concept of “precision farming,” which drives up productivity and drives down energy use. GPS guidance allows farmers to tend fields and plant crops literally to the inch, reducing wasted space, time and fuel, without even needing to steer machines with their hands. Although the upgrades for a moderately sized farm might cost $10,000, researchers at Purdue University have shown that the benefits outweigh the cost. For one thing, fuel use decreases. Incorporating GPS with field diagnostics allows farmers to map out soil conditions and fine-tune the application of chemicals, which can vary from one end of a field to the other, ultimately requiring less. Fields can also be worked at night and during fog and rain, when human visibility is limited, pushing productivity up.