SES faced a manufacturing challenge in preparing its SunCatchers for mass production though. “The systems at Sandia were basically hand-built,” says Charles Andraka, a Sandia engineer and Stirling expert who worked with SES on the system’s design. For the Phoenix site, he notes, Sandia and SES engineers built 60 units in three months. “We have to do that many in a day for the larger plants.”
In order to do this, SES turned to the experts in rapid production of engines and related parts: the automotive industry. In partnership with automotive companies such as Tower Automotive and Linamar Corporation, SES managed to reduce the parts in the PCU by 60 percent (to about 650) and slash the weight of the entire system by roughly 2,250 kilograms. Andraka highlights one example of the upgrade: in the original engines, he points out, gas passed over the outside of the engine, with pieces of tubes and fittings at either end, requiring a total of approximately 20 parts. “On the new engine, the gas passage is a part of the block with no external parts. It’s much more reliable, much cheaper to assemble, with fewer parts and fewer places to leak,” Andraka says. The new systems have been running on test sites for more than 100,000 hours.
Maricopa Solar also represents just one scalable module; each multi-megawatt field will be grouped first in 60-engine units that come together to generate 1.5 MW, then those larger units are linked to each other to produce up to 9 MW. Explains Coates, “With the large 750 MW commissions, we won’t have to wait until we have 750 MW of dishes before we start producing power. This means that the utility can get the power prior to the full build-out, which can take years to complete.” This is in comparison to parabolic trough or tower CSP technology, which doesn’t generate electricity until the entire system is complete.
Meanwhile, Tessera Solar, SES’s sister company in charge of development, is renegotiating contracts with utilities in California but expects to supply power at or below the cost of other solar technologies, and they plan to break ground on bigger solar Stirling engine power plants in Texas and California in 2010. Tisdale says he remains somewhat skeptical, but also optimistic: “This 1.5 MW site is key to demonstrating that it works.”