Learning to Live on Alternative Energy

Three landmark projects show us how to integrate renewable-energy strategies into architecture, without compromising design

March 2008

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By David Sokol, Russell Fortmeyer & Joann Gonchar, AIA

The Near North installation looks remarkably unchanged from Becker’s cardboard models. Becker mounted eight 520H turbines—each one featuring Savonius and Darrieus rotors welded onto a central shaft—on the roof in a horizontal axis. A vertical installation could produce 30 percent more energy, but it would have surpassed local height restrictions.

The turbines produce three-phase AC power from ARE 2,500-watt alternators mounted on each module. Each turbine also includes an Aurora 7200 Wind Interface Unit and an Aurora 3,600-watt inverter, manufactured by Magnetek. The interface converts the AC to variable DC and protects downstream inverters from high voltage surges via a diversion load. The inverter then converts that DC power into building-compatible 208-watt, 60-hertz variable amperage power. The project forgoes batteries, Becker explains, in order to minimize on-site toxicity and maintenance, and to assuage fire fears.

In Near North Apartments’ first months, the Aerotecture installation was producing a paltry 100 kilowatt-hours per module per month, but Becker has slowly improved average production to 300 kilowatt-hours per module per month. Currently, the 520Hs yield approximately 60 percent energy conversion, producing about 10 percent of the building’s power. Becker says his electronics could be optimized even further, although the alternator is proving an obstacle to achieving 80 percent efficiency: Just as the wind interface units were not designed for Savonius rotors, so most alternators are suited for the high rpm of internal combustion engines. Making another comparison to automobiles, Becker describes the disjunction between his rotors and his alternator as “having a car that’s too heavy for its engine. It runs, but it’s going to be sluggish on the hills.” To perfect his invention, Becker continues his search for an alternator suited for lower rpm, or may prototype one himself. David Sokol