A Dutch company says it has developed a new type of residential wind turbine that is far quieter and more efficient than conventional designs.The Liam F1 is a horizontal-axis turbine that uses a revolving collector in the shape of a nautilus seashell, rather than blades, to spin a generator.The company behind the project is The Archimedes, which takes its name from the Greek mathematician credited with inventing a nautilus-like device for pumping water now called the Archimedes Screw.According to the company’s website, the turbine can operate in wind speeds of between 4.5 and 78 miles per hour (from 2 to 35 meters per second).It wasn’t clear from the company’s website what the rated capacity of the turbine is (it’s written mostly in Dutch), and the company didn’t respond to an e-mail seeking more information. But the website EnergyMatters.com reported that with an average wind speed of 11 mph, the turbine would produce between 1,180 and 1,500 kilowatt-hours of electricity per year.The company claims the 5-foot-diameter device turns with very little resistance and is “virtually silent.” A noise rating for the turbine wasn’t apparent at the website.The website Gizmodo.com said the turbines would be priced at $5,400. Their availability in North America isn’t known. Water turbines operating on the same principleThe Dutch firm may be unique in manufacturing a wind turbine with an Archimedes screw, but a company called New England Hydropower Company LLC builds and installs hydroelectric turbines of a similar design.New England Hydropower, based in Beverly Farms, Mass., says its generators extract potential energy from “large blocks of slowly downward moving water” and aren’t harmful to fish. Photovoltaic systems are usually a better investmentFor purposes of comparison, $5,400 will pay for a photovoltaic (PV) system rated at 1,350 watts. Such a PV system would produce 1,969 kWh per year in Boulder, Colorado — significantly more energy than the high estimate provided by EnergyMatters.com for the Liam turbine installed at a site with an average wind speed of 11 mph. (It’s worth noting that a site with an average wind speed of 11 mph is very rare. Moreover, for a wind turbine to operate effectively, it must be mounted on a high tower; presumably, such a tower isn’t included in the quoted price of $5,400 for the Liam turbine.)For more information on residential wind turbines, see Backyard Wind Turbines and Resisting the Allure of Small Wind Turbines.