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Feb 022009
 

Besides some big customers, Brightsource has another claim to fame. In December, it was selected by the Geneva-based World Economic Forum as a 2009 Technology Pioneer. The award was given to companies who are “involved in the development of life-changing technology innovation and have the potential for long-term impact on business and society.”

BrightSource isn’t resting on its laurels. “The three main hurdles any solar thermal developer has are transmission, permitting and financing. Today those all look good but those are the areas where we pay most attention,” Wachs said.

Ausra, Inc.

The mission of Palo Alto, CA-based Ausra, Inc., according to the company’s website, is to “develop and deploy utility-scale solar technologies to serve global electricity and thermal energy needs.”

Ausra’s power plants generate electricity by driving steam turbines with sunshine. To be more specific, solar concentrators boil water with focused sunlight, generating high-pressure steam, which drives conventional turbine generators. What sets Ausra apart is its core technology , the Compact Linear Fresnel Reflector (CLFR) solar collector and steam generation system, developed by its founders in Australia. A CLFR collector gathers solar energy by reflecting and concentrating sunlight to roughly 30 times the intensity of sunshine at Earth’s surface. Mirrors focus on an elevated absorber, in which water is heated and boiled by the focused sunlight.

“I’m very much a scientist in businessman’s clothing,” said David Mills, Ausra’s founder and chief scientific officer. Mills was a physicist at the University of Sydney, Australia until 2004. It wasn’t until the university decided pursuing Mills’ patent on the CLFR technology wasn’t going to pay off that Mills was thrust into the aggressive, fast-paced business environment of Silicon Valley. He bought back the CLFR patent from the University of Sydney for $1, and it’s the basis for the technology Ausra is using today.

Mills’ modest tone belies his scientific vision.

“We could be regarded as a boiler-maker,” Mills said. “We had the idea to construct a low-cost technology to generate heat to produce electricity.”

“We developed an inexpensive way of using mirrors to develop reasonably high temperatures onto a network of pipes on a 1000-foot-long tower,” Mills explained. “And we put water into these tubes which is heated up. The water turns to steam and can run a turbine.”

Mills admits that while the concept sounds simple, “the execution is a little more difficult”.

“We have to have long mirrors running in parallel along the ground to these tubes, which are high on the tower, and the mirrors have to angle appropriately during the day to track the sun to make sure the sun’s heat is on the tubes. So we have to have accurate tracking mechanisms for that.”

What makes the system affordable, and thus scalable, Mills said, is that most of its parts come from basic commodities – glass and steel. “Our system is made of materials we can obtain anywhere. We don’t use special parts,” Mills said.

Ausra’s five-megawatt Kimberlina solar thermal plant near Bakersfield, California was launched in October 2008 amid much fanfare and an appearance by Governor Schwarzenegger. Ausra will sell the full output of the Kimberlina plant to PG&E under a long-term contract.

What’s the difference between these two company’s technologies?

Ausra uses networks of glass tubes to heat the water to make the steam to turn a turbine. BrightSource’s mirrors reflect sunlight directly onto the collection surface of the solar boiler approximately 300 feet in the air on top of a tower.

The Future for Solar Thermal

One of the factors that limits the reach of solar power is storage. These companies hope to change that. Ausra said it’s developing thermal energy storage systems to allow solar electric power to be generated on demand, day and night. “Storage is the key differentiator between solar thermal technology and PV or wind. PV or wind generates electricity directly, which then has to be stored in batteries. These solutions are far more expensive than storing in heat, as we do. We think solar thermal could eventually host the other technologies,” Mills said.

BrightSource currently advocates a pragmatic approach to storage. Its plants can be fitted with gas-fired boilers to produce steam when the sun is not shining, enabling the plants to produce electricity at any time.

Despite the global promise the World Economic Forum sees in BrightSource, Keely Wachs said the company has to proceed deliberately.

“Globally there is a significant opportunity, but we are a start up; we don’t want to get ahead of ourselves. Our primary focus today is getting these plants built here in the southwestern United States. It’s the most robust market,” he said.

Mills, the visionary, is looking further ahead.

“I published two papers last year, “ he said. “One looking at how solar plants, including thermal storage, could take the place of existing fossil fuel plants completely. In the second paper I assumed we would electrify the entire transport sector and put it on the grid.”

(Photo credits: top, Kimberlina solar thermal installation, Ausra Inc.; field of “heliostats” and rendering of proposed solar thermal installation, BrightSource Energy; Gov. Arnold Schwarzenegger and David Mills, Ausra Inc.)

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