The U.S. agriculture industry used nearly 800 trillion British thermal units (Btu) of energy in 2012, or about as much primary energy as the entire state of Utah. Agricultural energy consumption includes energy needed to grow and harvest crops and energy needed to grow livestock. Crop operations consume much more energy than livestock operations, and energy expenditures for crops account for a higher percentage of farm operating costs.
Agricultural energy consumption includes both direct and indirect energy consumption. Direct energy consumption includes the use of diesel, electricity, propane, natural gas, and renewable fuels for activities on the farm. Indirect energy consumption includes the use of fuel and feedstock (especially natural gas) in the manufacturing of agricultural chemicals such as fertilizers and pesticides.
Energy makes up a significant part of operating expenditures for most crops, especially when considering indirect energy expenditures on fertilizer, because the production of fertilizer is extremely energy-intensive, requiring large amounts of natural gas. For some crops like oats, corn, wheat, and barley, energy and fertilizer expenditures combined make up more than half of total operating expenses. The proportion of direct to indirect energy use varies by crop. For example, corn, which is also used as an energy input for ethanol production, has relatively low direct fuel expenditures but has the highest percentage of fertilizer expenditures.
The energy consumed in livestock operations is almost solely direct energy consumption and is relatively low compared with crop operations, both as a percentage of total operating expenditures and on a total energy basis. Livestock operations consume direct energy for ventilation systems, refrigeration, lighting, heating, watering, motors, and waste handling, whereas crop operations use energy to plant, harvest, irrigate, and dry crops. The energy consumed in the production of livestock feed is not included in this analysis of livestock energy consumption.
Distillate fuel is the dominant fuel for direct energy consumption for both livestock and crop operations. Distillate is used for crop tilling, harvesting, weed control, and other operations that require heavy machinery. Crop drying is another fuel-intensive farm activity, and the amount of fuel used varies by the type of crop and its moisture content. High-temperature dryers are powered by either electricity or propane.
Supplying water can also be an energy-intensive task. Although some farms have access to public water supplies, most farms pump water from wells and groundwater sources. Most pumping is done with electricity, but pumps in remote locations may use diesel or propane.
The chemicals used by the agricultural industry are a subset of the bulk chemical industry and include fertilizers and pesticides. Nitrogenous (ammonia-based) fertilizers require large amounts of natural gas as a feedstock and provide heat and power for processing. EIA's 2010 Manufacturing Energy Consumption Survey estimates that the U.S. nitrogenous fertilizer industry consumed more than 200 trillion Btu of natural gas as feedstock in 2010 and another 152 trillion Btu for heat and power.
In addition to being major energy consumers, some farms are using renewable resources to produce energy. Wind turbines, methane digesters, and photovoltaics are the most common on-farm renewables. Renewable energy can help to offset the need for purchased energy. In some cases, the renewable energy produced on farms is sold to electric power suppliers, providing additional income for farmers.