7 Most Frequently Asked Questions About Small Wind Energy Systems

1. How many turbines are needed to power a household or farm?

For a home or farm, one turbine is normally installed. The turbine's size is chosen to meet the energy requirements given the available wind resource. Turbines with power ratings from 1 kW to 25 kW are typically used.

For village electrification applications, both single and multiple turbine installations are common, and turbines up to 100 kW in capacity may be used.

2. How much land is needed for a small wind system?

The actual space required for a small wind turbine tower is quite small. It can be as small as one square yard, but as a general rule, at least one-half acre is recommended for a single small turbine installation.

3. What size tower is used for a small-scale wind turbine?

Usually a tower between 80 and 120 feet in height is supplied with the wind

turbine. Towers of this height raise the turbine above turbulence generated by

obstacles (such as buildings and trees) on the ground. Also, wind velocity increases with greater altitude, so wind turbine performance improves with height.

How do small turbine costs compare to the costs of other alternatives?

Small wind turbines (ranging in size from 250 watts to 50 kW) are often the least

expensive source of power for remote sites that are not connected to the utility system.

A study by the Congressional Office of Technology Assessment found wind to be

cheaper for meeting remote loads than diesel generators, photovoltaics, or utility transmission line extensions. (Micro-hydro also was found to be less expensive in many locations.)

Hybrid systems--wind/photovoltaic, wind/diesel, and other combinations--can often provide the most efficient and cost-effective option for rural electrification. Photovoltaics (PV)-- the direct conversion of sunlight into electricity--is often used to supplement wind power since PV tends to operate best in low wind months. Diesel generators or batteries can be used for backup power and to maintain power production during low wind seasons.

One study of an Arctic community with annual average wind speeds of 15 mph

compared the cost of a 500-kW diesel system to that of a 200-kW diesel generator and four mid-sized wind turbines. If found that the wind/diesel combination cost considerably more to install ($378,000 versus $125,000), but would deliver fuel savings of $90,000 per year, paying for itself in less than three years.

4. Why are small wind turbines better than diesel generators or extension of utility lines in developing countries?

Small wind turbines are better because they are more sustainable and offer a number of other socioeconomic benefits. Wind systems come in smaller sizes than diesel generators and have a shorter construction lead time than extending the utility lines ("grid"). For grid extension distances as short as one kilometer, a wind system can be a lower cost alternative for small loads. While wind turbines cost more initially than diesels, they are often much better from the user's point of view because of typical foreign aid practices.

Donor agencies, for example, typically supply diesels at no cost, but leave operational costs (fuel, maintenance and replacement) to be supplied by the local people. These expenses (in particular, fuel and parts) require scare hard currency. This usually leads to limited utilization and a shortened diesel lifetime due to inadequate maintenance.

Many countries must also import their fossil fuels, further magnifying the burden imposed by diesels.

5. How do small wind turbines compare with other renewable energy technologies suitable for decentralized rural electrification?

Wind power is very competitive with photovoltaics (solar), biomass, and diesel

generators, but is usually more expensive than micro-hydro. Wind is also very attractive for the ease with which the technology can be transferred to developing countries.

Generally speaking, wind power complements these other power sources by providing a least cost approach under certain conditions. This expands the range of potential projects, pointing to the day when decentralized electrification projects will be implemented on the same scale as current utility line extension projects. In many situations, the lowest-cost centralized system will be a hybrid system that combines wind, photovoltaics and diesel.

6. Aren't wind turbines too "high-tech" for rural people?

The high technology of a wind turbine is in just a few manufactured components such as the blades. A wind turbine can actually be much simpler than a diesel engine, and also require substantially less attention and maintenance. Some types of small turbines can operate for extended periods, five years or more, without any attention. With training and spare parts, local users can support the wind turbine equipment they use.

7. What companies make small wind electric systems?

The following AWEA members manufacture small wind electric systems:

•Atlantic Orient Corp.

•Bergey Windpower Co.

•Northern Power Systems

•Southwest Wind Power Co.

•Synergy Power Corp. (Hong Kong)

•Wind Turbine Industries Corp.

What companies make water pumping wind turbines?

The following AWEA members manufacture water pumping wind turbines:

•Bergey Windpower Co.

•Southwest Wind Power Co.

•Synergy Power Corp. (Hong Kong)

•WindTech International