Photos: Small wind turbines take shape

A small Skystream wind turbine from Southwest Windpower installed at a church converted to a home in Ohio. The turbine costs between $12,000 and $18,000 to install and pays for itself in as little as five years with the right conditions, according to the company. Like many small wind turbines, the Skystream has an integrated inverter and is designed to be connected to the grid. The incentives for small wind turbines improved recently so that consumers can get a 30 percent tax credit on the installation costs.

The challenge of microwind turbines is finding--and choosing--sites with sufficiently strong wind, particularly in cities.

Mariah Power's Windspire turbine is an example of a vertical axis wind generator. It is 30 feet tall and is capable of producing 2,000 kilowatt-hours per year, according to initial tests (the average U.S. home consumes about 10,000 kilowatt-hours). The company envisions the turbines will be placed on poles at people's homes or in public spaces, such as alongside roads. The company says the sound is imperceptible with 10-mile-per-hour wind.

Aerovironment's architectural wind turbines in action at Boston's Logan airport. The turbines are designed to be perched on the edge of flat-roof commercial buildings to take advantage of the gusty wind in those settings. The company has installed banks of these turbines in a handful of commercial buildings.

Cascade Engineering has the rights to sell this Swift turbine, which is already installed in dozens of locations in the U.K., some attached to roofs on homes. Like other wind turbines, the Swift has blades that turn and power a generator. But rather than the typical three blades, the Swift has five and a ring that goes around them. That "outer diffuser" ring cuts the noise level to 35 decibels and reduces vibration, according to the company.

Oregon Wind plans to release a beta version of its Helyx wind turbine later this month. The company is also developing a street light (pictured here) that is powered both by a small solar panel on top and the vertical axis turbine. The company says that the Helyx wind turbine doesn't produce that much electricity--a 42-inch turbine produces 80 watts with 28 mile-per-hour wind--but the materials and manufacturing costs are relatively low.