Green Options

Talk about rapid charging! Aerovironment today unveiled a near-megawatt scale electric vehicle charging system for the U.S. Army Tank Automotive Research, Development and Engineering Center (TARDEC).

The AV-800 delivers DC current at 800 volts, up to 999 amps in single-channel mode and 500 amps in independent dual channel mode. The bi-directional unit can also return power to the grid, with an efficiency of over 90%.

Utility-scale windpower is an important and growing part of the US energy portfolio. Farms ranging in size from dozens to hundreds of turbines can produce in excess of 60 megawatts of power. Plans for gigawatts of wind power are being proposed all over the globe, and new wind farms are regularly being proposed that outstrip one another to be the largest in their respective locations, or in the world. At the far end of the scale, the largest size wind turbines have a rotor diameter of 126 meters (413 feet), and are estimated to be capable of producing 20,000,000 kilowatt hours of electricity annually (enough to power as many as 5000 European homes). Since the power generated by a turbine increases exponentially as it gets larger, new turbines will continue to grow in size.

But small-scale turbines are perhaps a more exciting realm of development. The standard, propeller-style turbine is well established, and there are many suppliers for this kind of generator in a range of sizes. In 2007, Home Power Magazine had a roundup of more than a dozen small wind turbines ranging from 8 feet to 56 feet in diameter (the latter of which is far larger than even a large, inefficient household would need for their power requirements). Green Building Elements had a review of this article last year.

They have been around for centuries, but they are quickly becoming the darlings of the eco-friendlies and clean energy nuts. Windmills, or in this case, wind energy generators, come in all shapes and sizes.