Tracking the Sun: Concentrating Solar Power Faces Bright Future

"When the sun rises and gets above 10 degrees, the system will start tracking and we stay with it all day," he says.

That means 180,000 parabolic trough collectors controlled by 760 trackers moving flawlessly in concert, following the sun's path and collecting the heat to make clean electricity. That's the beauty of concentrating solar power (CSP), also known as solar thermal.

At 64 megawatts (MW) of generation capacity, Nevada Solar One is the largest CSP plant to be built in 15 years. While the plant won't come online until April, its construction marks the revival of an industry that has seen almost no market growth in over a decade.

The plant was developed by Acciona Energy and Solargenix Energy -- two companies that have worked hard behind the scenes to get the CSP industry up and running again.

The plant uses parabolic trough collectors to generate electricity. The mirrored troughs face the sky and direct sunlight to a large metal and glass receiver in the middle of the trough that holds circulating oil. The oil travels to heat exchangers, which heat water and create steam to run a turbine. Parabolic troughs are one of three commercialized CSP technologies.

Further down the row of parabolic troughs, Plant Manager Bob Cable admires the impressive devices before him.

"I've been working with this technology for the last decade," Cable says. "I've seen some impressive gains in technological advancement, and now we're seeing more broad acceptance of the technology as the market becomes more attractive."

Indeed, after roughly a decade of little growth for the industry, CSP is coming back strong. And it's not just parabolic trough collectors that are experiencing a boom. Power towers, which use heliostats to focus solar energy on a central receiver to produce steam, and dish systems, which use reflectors to power a generator at the dish's focus point, are making great strides in technological capabilities, lower costs and market acceptance.

But according to Thomas Rueckert, Program Manager for CSP Management at the U.S. Department of Energy, parabolic troughs are the most advanced.

"Because of the track record [the parabolic trough industry] had in southern California with the 354 megawatts (MW) operating -- and actually improving in performance -- I think you're seeing the financial institutions more willing to embrace trough technology because it's proven and the risks are less," said Rueckert.

Rueckert was referring to the 354 MW of parabolic trough collectors installed in California's Mojave Desert between 1984 and 1990. Those plants are still operating today, currently producing energy at around $0.12-$0.14/ per kilowatt-hour (kWh) and proving the technology can provide clean, reliable energy to the grid.

The Nevada Solar One plant will produce electricity at around $0.15-$0.17/kWh. While those costs are double what area residents pay for electricity, Nevada Solar One will sell energy to two utilities through a power purchase agreement (PPA). The PPA will ensure a fixed cost for the electricity over a long period, making the solar power economical down the line.

Now that global investment in CSP is increasing, technology costs are decreasing and renewable portfolio standards (RPS) in the U.S. are requiring more solar generation, project costs for all CSP technologies should come down significantly in the coming years, said DOE's Rueckert.

"All of those things have really opened the door," he said. "And it's interesting that all three technologies are pushing forward, which was kind of unexpected."

Back at Nevada Solar One, Acciona Solar's Cohen stands before the group of reporters and members of the solar industry who have come to witness the rebirth of CSP.



"The potential is huge. It was difficult to get the attention of the financial institutions in the U.S., but right now we have their attention. We get a lot of people asking us, 'how can we develop this technology?'"

Dr. Alex Marker, Research Fellow for Schott North America, Inc., stands to the side of Cohen, nodding his head. Schott is certainly feeling the positive impact of increased CSP development. To meet the demand for its glass receivers, the company brought a new receiver manufacturing facility online in Germany last summer and is developing another facility in Spain that will come online in early 2008.

"I think [the market] is going to grow drastically," says Marker, looking over at the receivers in the troughs. "We're happy to be a part of this new development."

Now that financial institutions are noticing CSP, companies like Acciona and Solargenix will be able to tap into the vast resource potential in the Southwestern U.S.

According to figures from DOE's Solar Lab, 20,000 MW of CSP capacity could come online in the U.S. by 2020 with the proper investment and technological capabilities. Rueckert seemed optimistic that a large amount of those resources will be tapped.

"When this plant comes online next month, it's going to be a great success," he said. "The market is exploding and things are really taking off."

Listen to this Thursday's Inside Renewable Energy Podcast for a report from Nevada Solar One.