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Agronomy Day 2007

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Alternative Energy for the Farmstead

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Dr. Xinlei Wang Dr. Xinlei Wang
Assistant Professor
Department of Agricultural
and Biological Engineering

Alternative energy has been creating interest worldwide due to an increasing concern over the sustainability of conventional fossil fuels and their impact on the environment. World energy consumption is projected to increase by 57 percent from 2002 to 2025. However, renewable energy accounts for only 8% of all energy consumption in the U.S. in 2005. To make a difference, many options are available for using renewable energy in your home - from passive solar space heating, solar water heating, geothermal heat pump to producing electricity at home with photovoltaic (PV) cells and small wind turbine, or to heat your home with your own product, such as, using a corn burner.

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Passive Solar Space Heating: Passive solar space heating takes advantage of the warmth from the sun through design features, such as large south-facing windows, and materials in the floors or walls that absorb warmth during the day and release that warmth at night when it is needed most. A sunspace or greenhouse is a good example of a passive system for solar space heating. A new home provides the best opportunity for designing and orienting the home to take advantage of the sun’s rays.

Solar Water Heating: Solar water heating is the most cost-effective use of solar energy. A typical residential solar water-heating system reduces the need for conventional water heating by about two-thirds. If you have a swimming pool or hot tub, you can use solar energy to significantly cut pool heating costs.

Solar PV Cells: Photovoltaic (PV) generation converts sunlight directly into electricity. It can provide electricity for residential and commercial buildings, including power for lights, appliances and air conditioning, and can also be a convenient source of power for pumping water, electrifying fences, or aerating ponds in remote locations. The estimated initial cost is $7-10/installed watt for PV systems. PV cells use the free energy from sunlight to produce electricity and have virtually no environmental impact.

Wind Turbine: Wind energy is one of the fastest-growing forms of electricity generation in the world. The United States currently generate more than 10,000 megawatts (MW) of electricity from the wind, which is enough to power 2.5 million average American homes. A 4-10 kW system can meet the needs of a typical home. The estimated initial cost is $2-4/installed watt for a typical small wind turbine system. The payback period is about 8-16 years with average wind speeds of 10 mph or more.

Geothermal Heat Pump: The geothermal heat pump, also known as the ground source heat pump (GSHP), is a highly efficient renewable energy technology that is gaining wide acceptance for both residential and commercial buildings. Geothermal heat pumps are used for space heating and cooling, as well as water heating. The geothermal heat pump transfers heat stored in the ground into a building during the winter, and transfers it out of the building and back into the ground during the summer. The ground acts as a heat source in the winter and a heat sink in the summer. The GSHP is one of the most efficient residential heating and cooling systems available today, with heating efficiencies 50 to 70% higher than other heating systems and cooling efficiencies 20 to 40% higher than available air conditioners. Geothermal systems pay for themselves in 5 to 8 years.

Incentive Programs: There are many incentive programs (Grant, Loan and Tax Credit) available to promote the renewable energy applications, such as:

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