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technology shines
200 years later, the Stirling engine finds its place in the sun.
Written by LINLEY ERIN HALL ’01 Photography by KIMBERLY TESKE FETROW
A nearly 200-year-old invention, the Stirling engine, is the ba- sis for the PowerDish™, one of the newest—and hottest—solar power technologies. Maury White ’61, chief technology officer and principal founder of Infinia Corp., has spent his career de- veloping and refining Stirling engines for a wide variety of ap- plications. Now his efforts have the potential to pay off in a big way, not only for him and his company but for the planet as well. “I’ve talked about just retiring,” White says, “but I’m really
seeing so much of what I’ve spent 44 years doing finally coming together, and I think I still can help carry it over that edge.” Robert Stirling invented his eponymous engine in 1816. It’s a
closed cycle, externally heated and cooled system with a gaseous working fluid. A displacer uses temperature differences to create a pressure wave, which moves a piston to generate power. In- finia focuses on free-piston Stirling engines, which have no parts that rub against each other and thus require no maintenance.
Furthermore, Stirling engines can be designed to use just about any heat source, which makes them excellent components for alternative energy technologies. The PowerDish looks like a satellite dish. A solar concen-
trator—a mirrored dish—collects the rays of the sun and fo- cuses them on one side of a Stirling engine. A linear alternator generates AC power within the hermetically sealed engine. The PowerDish can produce 3 kW grid-quality power with a conver- sion efficiency of 24 percent, much higher than the photovoltaic systems available today. White began working on Stirling engines during an intern-
ship with Atomics International that became a full-time posi- tion. After a few years, he joined a new Stirling engines group at Douglas Aircraft. This group eventually shifted to the Univer- sity of Washington and then was spun back out into industry as
Stirling Technology Company, later renamed Infinia. “Over the years, I’ve had just about every job within the pro-
gram and have been able to adapt to different requirements at different times,” White says. Most of the engines White has worked on were intended for
aerospace or medical applications. However, these projects laid important groundwork for the PowerDish. Research on a Stirling engine to power an artificial heart was particularly crucial. If such an engine breaks down, then the patient could die. Thus, White and colleagues developed extremely reliable engines, one of which ran in the laboratory for more than 11 years with no maintenance and no degradation in performance. The PowerDish is expected to have a lifetime of 25 years with occasional replacement of cool- ant and fan as the only maintenance necessary.
PowerDishes can produce 3kW grid quality power with a conversion efficiency of 24 percent.
time-honored
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