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| energy & agriculture |
| Introduction |
Modern agriculture is energy and water intensive. It requires various inputs to grow, harvest, process and transport food to the end consumer. At the current scale at which agriculture operates, it is the leading cause of freshwater scarcity issues—especially in the southwestern United States.
Crop irrigation accounts for 31 percent of water withdrawn in the United States. Pumping, moving and treating that water all requires electricity. In California, nearly twenty percent of electricity generated in the state is used for moving water to where it’s needed. While the large scale is modern, the energy-water interdependencies are not new. For example, farmers have used windmills to pump water and mill grain for centuries.
Agriculture’s energy use comes from direct and indirect sources. As an indirect use of energy, some fertilizers are produced from petrochemicals. A common set of chemical reactions synthesizes hydrogen and nitrogen into the fertilizer ammonia. The nitrogen, a naturally abundant element, comes from the atmosphere. However, the hydrogen is usually produced from fossil fuels, primarily natural gas. Other fertilizing agents, notably potassium and phosphorus, are mined, requiring yet another energy input. Additionally, there are many direct energy users; tractors and combines run on diesel fuel, for example.
Further environmental impacts have resulted from the increasing size and consolidation of farms. Fossil fuel use has increased since agriculture’s industrialization. In order to accommodate the increasing number of animals on a farm, more feed is required and, consequently, more fertilizer, water and energy is used. Furthermore, farms can create water pollution due to the runoff of fertilizers, pesticides, and manure.
Technology can allow farms to take advantage of local resources, agricultural outputs and waste streams to generate energy. Congressional mandates now require the production of ethanol from agricultural products, which are primarily—and controversially—derived from corn. Large dairy operations—another contentious practice—produce large quantities of manure and other environmental externalities. Although they do not eliminate all of the externalities associated with industrial agriculture, anaerobic digesters can use the manure to produce energy while composting the manure into a more benign product.
In addition to producing energy from agricultural products and residues, farms can host electricity on-site. The presence of multiple buildings on a farm, like houses and barns, provides plenty of roof space that can house solar panels. Some states are letting farms aggregate multiple meters for purposes of net metering, which would allow a large solar array to produce energy credits to offset energy consumed on multiple locations across the farm. Farms with large swaths of land in windy areas may host all or parts of a wind farm. The farmer can lease the land and generate another source of revenue, while continuing to make use of the surrounding land. Along with producing energy, farmers can cut back on energy use through more efficient technologies.
In order to meet a growing population’s needs with scarce resources, agriculture will need to become more efficient with energy and water. Carbon regulations and finite fossil fuel resources will help to ensure this, while newer technologies, like drip irrigation and alternative energy, will assist in meeting the challenge. That will not change the fact that agriculture is energy and water intensive. The ongoing effort to address how to best use those resources should be conducted in a sustainable manner.
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