As wind energy becomes an ever more significant source of clean, renewable power, there are more and more debates about where the turbines themselves should live. Big ones are put out to sea or in the middle of nowhere , and small ones can sit on your roof, helmet, or handlebars. It's even been proposed to fly them in the sky like kites. In Japan, a little one atop the roof of your taxi can charge your phone while you ride. On one front, turbines continue to get bigger. The German company RePower recently raised the bar when it announced the installation of the world's biggest wind generators destined for the Scottish North Sea. The mammoth turbines will each have a 5-megawatt capacity and a blade-span of 126 meters. On the other end, turbines also keep getting smaller, and small turbines keep getting better. Advancing technology, better design, and wider acceptance are helping to bring small wind power closer to home. Smoothly integrating small wind power into buildings has so far been a limited endeavor. Aerovironment, the California engineering firm behind the deceased EV1, is hoping to change that, and flip the "turbine on a stick" paradigm that is typically the norm. The forthcoming AVX400 is a small turbine that capitalizes on an urban airflow advantage: the fast-moving current that comes over the parapet of most city buildings. Engineers claim a 40% increase in efficiency as a result. The units are also intended to be less intrusive by operating at lower speeds, thus reducing noise and vibration. But Aerovironment hopes to take urban turbines beyond minimally intrusive to where they are considered a desirable and integrated component of design aesthetic, the way PV panels increasingly are becoming. Aerovironment went out of its way to allow this unit's four-foot blades to spin at lower wind speeds (as low as 4 mph), less for energy purposes than so that the blades can spend more time creating the aesthetic of motion, an idea they considered important to the technology's positive image. The optional canopy (pictured above) serves as a visual accent and as a potential protective guard for wildlife, although the company does not see a risk for birds or bats.
Small wind generation is a relatively simple concept and there is a good deal of do-it-yourself activity in building and tinkering low-output devises. Systems like Turby and Skystream hope to offer cost-effective distributed wind power for homes or businesses. The technology is not yet a no-brainer, however, and Aerovironment's contribution is not an exception. Environmental Building News calculates that the cost is a modest $5-$7 per watt of installed capacity, which, they point out, is roughly comparable to photovoltaic systems, and cheaper than building-integrated PVs. Currently being offered by Aerovironment is a 15-turbine package with a six kW output. The cost is $34,500 for turbines, inverter, installation, and maintenance, and is set to be available in the Fall of this year. EBN writes that "[u]nder decent wind conditions, this system should generate about 10,000 kWh per year, or about $1,000 worth of electricity at average retail rates." They add that higher rates, rebates, and integration with existing PV infrastructure could make for a sweeter deal. :: Aerovironment via Environmental Building News