For years now, electricity shortages have encouraged power companies to look for alternative sources of energy. And state governments are getting onboard as well. So far, 20 states, including Colorado, Massachusetts, New Jersey, and New Mexico, have established renewable energy production standards.
Add in the current sky-rocketing oil prices, and energy providers will be pushed even more to develop alternative energy sources.
Nowhere is this trend more apparent than in California, where rolling blackouts still affect a power-hungry population. It’s not surprisingly, then, that California may host the largest solar-energy project in history. Southern California Edison (SCE), with 13 million customers, has just announced a deal with Phoenix-based Stirling Energy Systems that could result in a huge solar farm.
The California utility is already the nation’s largest purchaser of renewable energy, providing its customer with more than 2,500 megawatts of wind, geothermal, solar, biomass, and small hydroelectric-derived energy, or around 18 percent of its total power load.
Now SCE has agreed to purchase upwards of 500 megawatts of electricity from Stirling Energy Systems – enough to provide all the energy needs to 278,000 homes – or more than all other U.S. solar projects combined. While neither company has disclosed the financial details, SCE said the system will not require state subsidies.
The effort will begin with a pilot project: a proof-of-concept facility with 40 solar dishes producing one megawatt of energy. The test will take place over the next 18 months, and, if successful, Stirling Energy Systems will construct a 20,000-dish array over four years, covering 4,500 acres – more than four times the size of the National Mall in DC – in the desert northwest of Los Angeles.
"From our perspective, Stirling has established the viability of this at a laboratory level," says SCE spokesperson Gil Alexander. "This could be a turnaround point for solar."
Stirling’s dish technology, which was first developed by McDonnell-Douglas in the mid-1980s, makes use of a heat-driven engine, rather than photovoltaic panels. The company’s deal with SCE marks its first utility-scaled energy application.
In the Stirling solar system, each dish is a round, mirrored surface measuring 37 feet in diameter that reflects and focuses light into the receiving end of a Stirling engine. The engine itself, which was actually invented in 1816 by a Scotsman, Robert Stirling, is driven by the heating and cooling of a closed gas (see Notebook).
To date, Stirling engines – with their minimal emissions, long life spans, and quiet operation – have produced refrigeration and even powered submarines. In the solar version, the dishes concentrate heat, which can rise to more than 720 degrees Celsius, causing hydrogen gas to expand, which in turn drives pistons and an electricity generator.
Stirling Energy Systems has been operating a six-dish system since January at the Sandia National Laboratories test facility in New Mexico. There, the company converted its centuries-old technology into an efficient means of energy generation by using modern materials and programming that tracks solar progression and accounts for cloudiness and winds. The six dishes generate enough power for six homes, with their peak energy flow coming at the hottest parts of the day – when utility needs are greatest.
"Our systems have peak efficiency of 29.4 percent – that’s the record for converting solar to grid-quality energy," says Stirling CEO Bruce Osborn.