Mariah Power says its Windspire vertical-axis wind turbine is now commercially available, after having passed performance tests.

The Windspire costs $4,995, which includes the inverter, pole, and other equipment.
Typically, small-wind turbines such as Southwest Windpower's 1.9-kilowatt Skystream, are best suited for homes with a substantial amount of land.
Mariah Power said the Windspire is aimed at residential customers in urban, suburban, and rural areas. It has already been installed in a handful of U.S. locations.
"(Its) efficiency is on par with most propeller-based wind turbines, but it is priced much lower. It is also much quieter because the rotor glides through the air at only a third the speed of propeller blades, and it can capture wind instantly from any direction," Mariah Power CEO Mike Hess said in a statement.
The Windspire produces about 1.2 kilowatts, or 2,000 kilowatt-hours, per year, according to Mariah's brochure. It works best in 12 mph average winds or higher, and it generally requires half an acre of land, the company said. It's 30 feet high and has a 2-foot radius.