In this issue
		Energy Services Bulletin home page
		Recycling promotion highlights energy efficiency, local resources
		MHA Nation tackles wind development one step at a time
		ACORE committee provides renewable energy forum for utilities
		Schools, forests, taxpayers all win with Fuels for Schools
		Utilities join projects to promote energy-efficient homes
		SOLAR 2006 focuses on renewable energy's role in climate recovery
		Automated meter reading spreads through Western territory
		Nebraska utility, university partner on energy research center
		Western plans workshops to demystify power factor
		New Equipment Loan manager brings experience, plans to job
		Topics from the Power Line: Powering irrigation with renewable energy
		Energy shorts
		Technology spotlight: Pressure-independent valves - Do they save energy?
		Calendar of events

Powering irrigation with renewable energy

Editor's note:The Energy Services Bulletin features real answers to real questions posed to our staff at the Energy Services Power Line. We hope you find it useful.

Question:

I would like information on solar and wind technologies for agricultural applications such as irrigation, cattle and alfalfa production.

Answer:

Both wind and solar have been used in agricultural applications for years. The old-fashioned windmill was common on farms and ranches for much of the 20th century. In the 1950s, many American farmers used solar crop drying.

Over the last 20 or 30 years, however, electricity in rural areas became cheaper and most of these applications fell by the wayside. With recent dramatic price increases for electricity and propane, we seem to be coming full circle. Several papers written on this topic by government and non-governmental agencies are cited below. They will give you a good understanding of both photovoltaics and small-scale wind energy systems. 

Wind Systems

Small-scale wind energy technology is readily available and cost-effective, but has some maintenance issues. While reliable, small wind turbines also seem to break down when you need them the most or in high winds, making repairs sometimes difficult. However, any mechanical device will break down sooner or later. Even given the maintenance needed, they are good energy providers.

It is important to find out if your site has enough sustainable wind annually. You should measure the wind speed at your site for one full year. A small wind energy system needs an average annual wind speed of at least 10 to 12 mph.  Your utility may be able to help you borrow an anemometer to measure the wind on your site.

Wind turbine costs vary because they are closely associated with siting and installation prices. Systems of around 500 watts to 2 kW are typical of small installations such as homeowner sites, and used turbines of this size are often available. A small wind turbine and related equipment, such as outdoor flood light and power conversion equipment, could cost between $350 and $1,000 not including installation, operation and maintenance.

Labor for wind systems is usually more expensive than for solar systems, partly because a turbine must be built to withstand high winds. Also, maintenance costs for wind systems are higher because of the complexity of the equipment.

For more information about the advantages and challenges of small application wind power, check out these resources:

• Small Wind Electric System Turbines. U.S. Department of Energy

• Wind Energy Comes of Age. By Paul Gipe, John Wiley & Sons, 536 pages. Your local library or bookstore may be able to get this book.

• American Wind Energy Association small wind resources.  Includes a list of major manufacturers of 50-kW to 1-MW turbines.

Solar Technology

Solar technology has only been popular for the last 20 years in the United States and has become fairly common in the last five years. Solar arrays have no moving parts, produce no pollution and are becoming less expensive every day thanks to volume production.

Many remotely located road signs and roadside emergency call boxes use solar power. Even in cloudy areas, solar power offers a cost-effective alternative to digging up roads and stringing power lines to signs that need very little electricity. In northern countries, PV systems can use large battery banks to store electricity for use when there is insufficient sunlight.

A small solar-powered lighting system can be purchased for around $100. Larger systems range from $250 to $1,000, depending on the size. With solar lighting systems, installation costs depend largely on the site: Is it shaded or open? Is it near salt water that may cause corrosion? Do the cells need to be raised above obstructions? Is it accessible for future maintenance?

Connecting to the Grid

Several states have net metering laws that require utilities to let small electricity providers connect their systems to the local grid. Such laws allow the generator owner to "spin" his or her home electricity meter backwards when the system is producing more electricity than is being consumed. The home generator is allowed to produce revenue, not exceeding the amount the residence consumes in a one-year period. In other words, you can only reduce your electric utility bill to zero. The system cannot make more money than what your electric bill would be.

Also, utilities mandate certain safety measures to make sure a system is not putting electricity into the grid when there is a power outage on that section of the grid. This prevents utility line workers from getting shocked by electricity the system produces.

Here are some additional resources to help you decide if solar power is right for your operation:

• Solar Radiation Basics. A DOE Web site.

• Agriculture, Irrigation and Water Efficiency. Western Area Power Administration. Online order form.

• Using Solar Energy to Pump Water for Livestock in Remote Areas (12kb pdf). California Energy Commission publication.