16-08-2012, 01:13 PM
ENERGY CONSERVATION IN AGRICULTURE
ENERGY CONSERVATION IN AGRICULTURE.doc (Size: 33.5 KB / Downloads: 41)
1. Solar Light and Heat
One of the simplest ways to use solar energy is to design or renovate buildings and barns to use natural daylight instead of electric lights. Dairy operations using "long day" lighting to increase production can save money with skylights and other sun-lighting options.
The sun's heat can also be used to warm homes and livestock buildings. In confinement operations, a steady supply of fresh air is critical to maintaining animal health, but this can result in substantial heating bills. "Active" solar heating systems, which use heat boxes and fans, can warm the air, saving on fuel. "Passive" solar designs, where the building is designed to take advantage of the sun automatically, are often the most cost-effective approach.
Solar water heaters can provide low- to medium-temperature hot water for pen cleaning. Dairy operations can use solar heated water to clean equipment and to warm and stimulate cows' udders. For homes or farms with electric or propane water heaters, solar collectors can save hundreds of dollars per year.
2. Crop and Grain Drying
Using the sun to dry crops and grain is one of the oldest applications of solar energy. Solar drying equipment can dry crops faster and more evenly than leaving them in the field after harvest, with the added advantage of avoiding damage by birds, pests, and weather.
A typical solar dryer consists of an enclosure or shed, screened drying trays or 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 farmer added a dark metal roof to a hay barn to serve as a solar collector, with a fan to draw the hot air through the barn. This eliminated the need for an oil or electric heater, saving $4,100 per year in reduced energy and maintenance costs. Moreover, since the farmer did the work himself, the up-front cost was only one-eighth of what an oil heater would have cost.
If a farm has a crop dryer already in place, it may make sense to install a low-cost solar heater to supplement a propane or oil heater. The farmer would save on fuel costs while still being able to dry crops in cloudy weather.
3. Greenhouse Heating
Commercial greenhouses often rely on the sun for lighting, but on gas or oil heaters to maintain constant temperatures. A solar greenhouse uses building materials to collect and store solar energy as heat. Insulation retains the heat for use during the night and on cloudy days. To capture the most sunlight, a solar greenhouse generally faces south, while its northern side is well insulated, with few or no windows. A gas or oil heater may be used as a backup.
4. Remote Electricity Supply
Sunlight can also generate electricity. Photovoltaic (PV) panels are often a cheaper option than new electric lines for providing power to remote locations. And because they require no fuel and have no moving parts, they are more convenient to operate and maintain than diesel or gasoline generators. In some areas, the distance from a power source at which PV becomes more economical than new transformers and electric lines is surprisingly short—often as little as 50 feet.
PV systems are a highly reliable and low-maintenance option for electric fences, lights, and water pumps. Although current prices for solar panels make them too expensive for most crop irrigation systems, photovoltaic systems are economical for remote livestock water supply, pond aeration, and small irrigation systems. In addition, the cost of PV is projected to decline significantly over time, which will make more applications cost-effective.
5. REDUCING ENERGY COSTS IN BUILDINGS
Stop Air Leaks: Whether in farm buildings or in homes, air leaks are a major cause of heat loss. Windows, doors, and roofs are primary culprits. The total amount saved varies, but older structures usually realize the most savings. Caulking and weatherstripping around windows and doors can reduce heat loss up to 37 percent in those areas. Some older buildings may need to be modified if heat losses are great.
Insulate Adequately :Add insulation (R-19 or 6 inches for walls and floors, R-38 or 12 inches in attics) if current insulation is not enough. Increasing attic insulation from R-19 to R-38 reduces heat loss through the attic by up to 50 percent. Also insulate farm shops and other buildings.