Energy Conservation

The characteristics and efficiency of energy use as a vital input in U.S. agriculture. American agriculture relies on non-renewable sources of energy that are consumed both on and off the farm to provide production inputs. Conservation of energy is a major concern and has been moderately successful. Agriculture also produces renewable energy such as bio-fuels that are used both on and off the farm.

Fundamentals of Energy Use

Energy is a vital input for agricultural production systems in America, as it is in all industrialized countries. With current practices, farms import and use large amounts of non-renewable energy in farming operations. The provision of agricultural transportation, the support of farm families, and on-farm processing of agricultural commodities consume additional large quantities of energy.

The non-renewable forms of energy include the energy commodities derived from crude oil, natural gas, coal and nuclear. Those energy commodities include gasoline, diesel fuel, LP gas, natural gas, electricity, fuel oil and lubricants. A small portion of agricultural energy consumption currently consists of renewable energy commodities. Energy commodities derived from renewable energy sources include hydro, photovoltaic, and wind generated electricity, wood and other biomass, alcohol from biomass or wastes, and vegetable oils.

Agricultural production uses energy both as direct energy in the form of energy commodities used on the farm and as indirect energy. Indirect energy is the energy expended off the farm that enables the provision of inputs used on the farm for agricultural production. This includes energy required for consumable inputs, such as fertilizers, pesticides, packaging materials, small tools, labor and veterinary supplies. Indirect energy also includes energy used for capitalized inputs, such as machinery, buildings, irrigation systems and land improvements. Indirect energy consumption for agricultural production in the U.S. is the hidden energy input that tends to be overlooked or inadequately accounted for. Indirect energy consumed for American agricultural production is about twice the direct energy consumed.

In addition to the energy used for agricultural production, rural America also consumes energy for forestry, fisheries and farm homes. Energy consumed in the home is largely supporting final consumption as opposed to agricultural production. But some of the energy consumed in the farm home supports agricultural production by enabling the farmer and farm family to work in agricultural production. That is labor energy input for agriculture.

Costs

The costs of energy are an important, although not the largest, component of total costs of agricultural products. Energy costs increased sharply in 1973-1974 and in 1979-1980 due to the OPEC cartel’s actions. These increased costs have prompted many and diverse efforts to conserve energy in agricultural production. Public funds supported research to conserve energy and to develop renewable energy sources, educational programs disseminated information on conservation practices to farmers, and some conservation practices were adopted by farmers. Also, as American industry became more energy efficient, the energy required to provide some of the inputs to production agriculture was reduced. American agriculture became more energy efficient. From the early 1980s, however, energy prices have generally moderated until the increases of the most recent several years, so that inflation-adjusted prices of much agricultural energy today are about what they were before the energy crisis. As non-renewable energy sources are consumed, energy costs will likely continue to rise, leading to a renewed emphasis on rural energy conservation. Finally, another “cost” of energy is the environmental effects of energy consumption, including increased global warming and carbon emissions.

Energy, both that used directly on farms and that used indirectly to supply agricultural inputs, is critical for our industrialized agricultural system to function. Historically, until the energy crisis, energy had been cheap and was used liberally. Our agricultural system evolved based on the historic relative costs of numerous inputs, including energy. The infrastructure supporting agriculture has developed similarly. It would be very costly and difficult to replace or extensively modify that infrastructure and the capital investments in farm equipment, buildings, irrigation systems and such.

The different characteristics of each energy commodity greatly influence the use of energy. Energy density, the quantity of energy per unit volume or weight, is a characteristic favoring gasoline, for example, over wood. Some forms of energy are easier to store than others. For example, it is easier to store diesel fuel (in tanks) than electricity (in batteries). Costs of energy commodities vary: electricity is more costly per unit of energy than diesel fuel. The cost of energy is an important determinant of the costs of agricultural commodities, as energy costs must be included in the total cost of the commodity in order for its production to be profitable and to continue. As costs of energy increase, those agricultural commodities requiring more energy will become more expensive, less competitive in the marketplace, and ultimately less available to consumers.

Modes of Usage

The modes of energy use in agricultural production are many. Direct uses include powering engines in mobile field equipment (tractors, combines and other self-propelled farm equipment) and in farm vehicles, stationary engines using diesel or natural gas to power irrigation pumps and farmstead equipment, electric motors to power farmstead equipment and irrigation pumps, and combustion of fuels or electrical resistance heating for crop drying and heating of farm structures. Mobile field equipment uses mostly liquid, high energy density fuels. Indirect energy uses include energy to provide fertilizers, pesticides, and other expendable supplies, capital expenditures, and human labor. The total amount of primary energy, which includes all direct and indirect energy, that is used to support production agriculture is only about 2-3 percent of all energy consumed in the U.S., or about two quads (quadrillion Btu). Several patterns characterize agricultural energy use in the U.S. Regional differences exist due mainly to where different commodities are produced; for example, fruits and vegetables are more energy intensive than field crops. During the year, more energy is consumed at planting and harvesting times than otherwise. Energy must be available in adequate quantities at the times needed for such critical seasonal operations. Available technology influences energy requirements; as technology changes, energy consumption may decrease as improvements are adopted by farmers.

A unique aspect of energy and agriculture is that agriculture is essentially the only industry (other than the energy industry) that can produce energy. Agriculture can produce renewable energy by converting sunlight to carbohydrates through photosynthesis. Several issues exist. One is the relationship between the quantity of energy produced and the quantity of energy required in order to produce it. The ratio of energy produced to energy consumed must be greater than unity for an energy production system to be viable. A second issue is whether the energy is used on the farm or sold. A third is any wastes and pollution due to agricultural energy production. A fourth is that the cost of producing renewable energy less subsidies must be competitive with the cost of non-renewable energy. A fifth is the effects of production of renewable energy on the prices of other agricultural commodities. And a sixth is the possible effects of renewable energy production on the sustainability of agricultural systems.

Sources of energy produced within agriculture include wood (consumed in direct combustion or gasification), other biomass, peat, bagasse, crop residues, wind for electric power or mechanical energy and water pumping, solar thermal (used for grain drying, livestock housing, greenhouses and water heating), underground tubes for thermal heat exchange, photovoltaic, vegetable oils, ethanol from carbohydrates and celluloses, methane from animal and food processing wastes, and heat pumps. A few of these are now competitive, and more are likely to be in the future.

Current Situation and Future Expectations

The energy situation is dynamic. The emphasis concerning energy since the energy crisis of 1973-1974 has shifted from availability of energy supplies to the cost of energy and to the efficiency of energy use. Over the more than three decades since the energy crisis, industry has become more efficient in producing many goods and services, including agricultural inputs. Many agricultural inputs now require less energy than before to manufacture, thereby conserving energy. New technology is continually being developed, some of which conserves energy. Finally, as non-renewable energy sources are depleted in the future and energy prices increase, there will be a shift from non-renewable to renewable energy.

Energy conservation in rural America has many aspects. The main factor governing which energy conservation practices are adopted by farmers is the practices’ economic viability. To be accepted, an energy conservation practice must also save money. A second important factor is how efficiently energy is used in agriculture. The efficiency with which energy is utilized is best measured by energy productivity. Energy productivity is the quotient of the quantity of a specific agricultural product produced and the energy required to produce it. A third factor is that energy and other inputs are partially substitutable for others such as land, labor and capital. Generally, as the quantity of any one input is increased, the law of diminishing returns results in the productivity of that input decreasing. As the quantity of energy is increased, its productivity decreases and the productivity of other inputs increases.

Effective energy conservation on the farm involves evaluation of many possible energy conservation practices in the context of a specific farm, selection of the best viable practices, and their implementation. Among proven practices to conserve energy is limited tillage (also termed conservation or minimum tillage). Fewer trips are made over the field, reducing liquid fuel consumption. Although herbicide use is often increased, a net reduction of total energy inputs usually occurs. Another proven energy conservation practice is reduced inputs of fertilizers by better use of soil testing, following of recommendations and avoidance of overfertilization. Integrated pest management (IPM) generally reduces use of pesticides and may save energy. A continuing shift to more efficient diesel engines in tractors and other equipment has reduced their fuel consumption. Better management of tractors by proper selection of gears and throttle settings, and optimum ballast and wheel slip also have conserved energy. Recycling of plant nutrients from livestock operations to replace chemical fertilizers often results in a net saving of energy. Modifications that replace transportation and less than optimum management with information technology can reduce energy consumption. Agricultural utilization of waste low grade heat from electric power plants and other sources can replace fuel for heating of greenhouses or perhaps other uses of thermal energy. Perhaps the most positive prospect for future energy savings is precision farming, based on the use of global positioning systems (GPS) and geographic information systems (GIS). Precision farming is the application of crop inputs in optimum quantities that vary spatially in the field dependent upon specific parameters determined for different locations. Soil characteristics such as soil type, fertility and moisture content can be used in conjunction with past yields to determine the optimum levels of application of fertilizers, pesticides and irrigation.

The idea of energy self-sufficiency has been advocated, in which a farm would produce all its energy requirements through renewable energy sources and not rely on off-farm sources of energy. But energy self-sufficiency appears to have no more validity than self-sufficiency in any other input, say, capital or information. Modern economies have instead developed based upon the fact that different entrepreneurs have different advantages and resources and therefore also have advantages in producing selected goods and services. Therefore, various firms and countries are interdependent rather than independent.

Policy

Policy can influence agricultural energy conservation practices by farmers. Energy conservation policy can range from educational programs, incentives and subsidies to allocations and controls. Current policy seems to comprise a moderate educational effort, assurance of energy supplies, and freedom for prices to seek their own levels.

— Richard C. Fluck

See also 

Mining Industry; Electrification; Environmental Protection; Petroleum Oil Industry; Policy, Environmental; Solar Energy; Wind Energy

References

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