Sun and Wind Combine to Power Home
The designer of the “Ridgeblaster” wind turbine and the creator of a photovoltaic concentrator using Fresnel mirrors have worked it out so that their two complementary energy systems for powering homes can work together on one roof.
Both are “most commented-on ideas” in General Electric’s “Ecoimagination Challenge.” The Challenge holds annual open submissions of new technology ideas for “Powering Your Home and “Powering the Grid.” The program is a joint venture of GE and a number of venture capital firms, designed to encourage businesses, students and others to submit their ideas. The winners each get $100,000 to move their ideas closer to realization. (Presumably GE and the venture capital firms get first dibs on the ideas they like.)
The Smartwind Ridgeblaster solves a lot of problems that conventional stand-alone turbines present to homeowners and to their neighborhoods. Almost nobody likes the way they look; they are intrusive, in-your-face machines; and those that are roof mounted need a lot of expensive reinforcement to prevent them from taking the roof off when the wind gets strong enough.
The Ridgeblaster solves these problems with a row of serial, horizontally mounted turbines designed to sit on the ridge of a conventional peaked roof. The fins are made of strong, silver-metalized EPP (a high-tech foam). Their light weight assures a low kick-in speed – so it doesn’t take a lot of wind to get them going. Their position takes advantage of a pitched roof’s “funnel effect,” which lifts and accelerates passing winds up and over the pitched roof surface. Where they sit, these turbines can catch the wind from all directions. The fact that the turbines are light in weight and distributed along the whole ridge means that the Ridgeblaster system doesn’t stress the roof on which it’s mounted. The simplicity of the design and the use of low-cost materials will make this system cheap to produce – and hopefully cheap to buy and install.
The Ridgeblaster’s designer, James Post of Smart Solar Co, has joined with one of his competitors in the challenge to create a more-than-the-sum-of-parts offering that combines wind with solar. Shawn Buckley’s low-cost linear Fresnel PV Concentrator is a 4-by-8-ft solar multi-panel module that uses a Fresnel mirror assembly to concentrate the sun’s light onto a small area in each panel. (Fresnel lens and mirror designs are a simple and inexpensive way to focus light when you don’t need high resolution.) This design has several plusses, the biggest one being that you reduce the amount of expensive silicon PV surface you need because the lens concentrates the light. You’d need several more expensive solar panels to get the same amount of power that Buckley’s design provides, so installation is simplified too.
The benefit of combining the two systems is obvious. You don’t always have both wind and sun, but you often have one of them going for you, so you are likely to be generating your own power more often than from either alone. But the most constant advantage is that the two designers have worked it out so that both systems can use the same inverter. (Solar and wind systems both generate DC that must be converted to AC.) Using a single inverter will save a significant chunk of the cost for any homeowner who opts to have both systems bringing the sun and the wind to run his home.