Solar Energy and Agriculture
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For More Information Centre for the Analysis and Dissemination of Demonstrated Energy Technologies www.caddet-re.org Cooperative Extension Publications 630 West Mifflin Street, Room 170 Madison, WI 53703-2636 (608) 262-3346 www.uwex.edu/ces Midwest Plan Service Up with the Sun: Department of Agricultural Engineering University of Illinois 1304 West Pennsylvania Avenue Urbana, IL 61801 Solar Energy Solar power charges an electric fence (217) 333-7964 on this Colorado ranch. www.mwpshq.org Photo: Warren Gretz, NREL and Agriculture National Renewable Energy Laboratory Remote Electricity Supply Renewable Resource Data Center Sunlight can also generate electricity. 1617 Cole Boulevard Golden, CO 80401 Photovoltaic (PV) panels are often a Solar energy-power from the (303) 384-6979 sun-is clean and unlimited. Cap- cheaper option than new electric lines for rredc.nrel.gov providing power to remote locations. And turing the sun’s energy for light, because they require no fuel and have no PV Design Assistance Center heat, hot water, and electricity can Sandia National Laboratory be a convenient way to save money. moving parts, they are more convenient to Albuquerque, NM 87185-0753 Whether drying crops, heating operate and maintain than diesel or (505) 844-3698 gasoline generators. In some areas, the www.sandia.gov/pv buildings, or powering a water distance from a power source at which PV pump, using the sun can make the Solar power controls this irrigation system. Real Goods Trading Corporation farm more efficient. Photo: Siemens Solar Industries, NREL becomes more economical than new 555 Leslie Street transformers and electric lines is surpris- Ukiah, CA 95482-5507 Solar Light and Heat ingly short-often as little as 50 feet. (800) 762-7325 www.realgoods.com The amount of energy from the sun One of the simplest ways to use solar PV systems are a highly reliable and low- that reaches Earth each day is enor- energy is to design or renovate buildings maintenance option for electric fences, U.S. Department of Agriculture, 2002 Farm Bill mous. All the energy stored in Earth’s and barns to use natural daylight instead of lights, and water pumps. Although current Renewable Energy Incentives reserves of coal, oil, and natural gas is electric lights. Dairy operations using “long www.rurdev.usda.gov/rd/farmbill/9006resources.html prices for solar panels make them too equal to the energy in just 20 days of day” lighting to increase production can expensive for most crop irrigation systems, sunshine. While desert areas such as save money with skylights and other sun- photovoltaic systems are economical for Arizona and Nevada get more sun than lighting options. remote livestock water supply, pond other parts of the United States, most The sun’s heat can also be used to warm aeration, and small irrigation systems. In areas receive enough sunshine to make homes and livestock buildings. In confine- addition, the cost of PV is projected to solar energy practical. ment operations, a steady supply of fresh air decline significantly over time, which will is critical to maintaining animal health, but make more applications cost-effective. Putting the Sun to Work this can result in substantial heating bills. on the Farm “Active” solar heating systems, which use heat boxes and fans, can warm the air, To find out more about renewable energy and agriculture, visit the Solar energy can be used in agriculture saving on fuel. “Passive” solar designs, Clean Energy section of the UCS website at www.ucsusa.org/clean_energy. in a number of ways, saving money, where the building is designed to take Or, write to: Clean Energy Program, Union of Concerned Scientists, Two increasing self-reliance, and reducing advantage of the sun automatically, are Brattle Square, Cambridge, MA 02238, or call (617) 547-5552. pollution. often the most cost-effective approach. to draw the hot air through the barn. This eliminated the need for an oil or electric Badgersett Research Farm equipment, they have also gained heater, saving $4,100 per year in reduced Solar Greenhouse significant tax benefits. energy and maintenance costs. Moreover, Philip and Mary Rutter built a “It works!” Philip Rutter says. since the farmer did the work himself, the solar greenhouse on their farm in “So far this year, we’ve grown about up-front cost was only one-eighth of what Canton, Minnesota. The greenhouse an oil heater would have cost. 20,000 plants in here, which is actual- is partially earth-sheltered because ly a small fraction of what we expect If a farm has a crop dryer already in of the cold growing area, and the the building to be able to produce. place, it may make sense to install a low- roof is superinsulated with glass This is not a far-out alternative kind cost solar heater to supplement a propane This solar barn dries hay while saving money. windows facing only south. Six Source: Centre for the Analysis and Dissemination or oil heater. The farmer would save on of building. This is a very straight- of Demonstrated Energy Technologies fuel costs while still being able to dry crops photovoltaic panels and a small wind forward moneymaking operation.” turbine provide power for lighting, In addition to saving money on Solar water heaters can provide low- to in cloudy weather. fans, water pumping, and opening medium-temperature hot water for pen energy bills, “the energy is substan- Greenhouse Heating and closing large insulating shutters. cleaning. Dairy operations can use solar tially more reliable,” Rutter says. heated water to clean equipment and to Commercial greenhouses often rely on No backup heating system or power “In a traditional, above-ground warm and stimulate cows’ udders. For the sun for lighting, but on gas or oil source is needed. Extending power greenhouse, if you have a heating homes or farms with electric or propane heaters to maintain constant temper- lines to the greenhouse would have system failure in the winter, you can water heaters, solar collectors can save atures. A solar greenhouse uses building required dedicating a substantial lose your crop in a hurry. Unless the materials to collect and store solar hundreds of dollars per year. amount of land to the power roof blows off, which is really not energy as heat. Insulation retains the heat company, clearing trees, and losing possible, this building can’t freeze in Crop and Grain Drying for use during the night and on cloudy the productive potential of the land. the wintertime because of its earth- Using the sun to dry crops and grain is days. To capture the most sunlight, a solar sheltered and superinsulated aspects. one of the oldest applications of solar greenhouse generally faces south, while The total cost of the system was energy. Solar drying equipment can dry its northern side is well insulated, with $5,600, which is higher than standard That security may make the crops faster and more evenly than leaving few or no windows. A gas or oil heater greenhouses of the same size. But difference between whether our them in the field after harvest, with the may be used as a backup. the Rutters estimate that the system business survives in the long term.” added advantage of avoiding damage by will pay for itself in 10 years through birds, pests, and weather. Source: Solar Living Source Book: The Complete Guide energy savings. By financing the to Renewable Energy Technologies and Sustainable Living, A typical solar dryer consists of an system as part of their mortgage Real Goods, Ninth Edition,1996. enclosure or shed, screened drying trays or and depreciating it as business racks, and a solar collector. In a simple design, south-facing windows let sun into the shed. Other designs use a dark-colored box with a glass cover to capture the heat. Natural convection or a fan moves hot air through the crops to dry them. While the cost of a solar collector can be high, using the collector to heat other buildings at other times of the year makes it more cost-effective. And small, low-cost dryers are easy to make out of simple materials. At one installation in Switzerland, a The sun is a reliable source of heat, light, farmer added a dark metal roof to a hay and power for greenhouses. barn to serve as a solar collector, with a fan Photo: Warren Gretz, NREL Background photo: Rick Hinrichs.