Don’t look directly at the tower. It’s tempting, but really–don’t.” Mike Bobinecz, vice president of construction management at BrightSource Energy, is just trying to preserve my eyesight–and presumably his company’s safety record. Bobinecz is one of my guides at the Ivanpah solar-thermal plant, and as he walks me through this project on the edges of California’s Mojave Desert, it’s hard not to glance, at least through darkly shaded glasses, at the thousands of angled mirrors reflecting the morning sun. At the center of the circles, Ivanpah’s nearly 500-ft.-high (150 m) Unit 1 solar tower glows with an incandescent white light that burns an afterimage on my retinas from more than a mile away. “It’s like looking at the magnification of 28,000 suns,” says Bobinecz. This is solar energy at its most concentrated and most powerful.
Unit 1 is the first of three towers that will be part of the Ivanpah project, which sprawls over nearly 4,000 acres (1,600 hectares) of public land near the California-Nevada border. By the time the entire plant is completed later this year, it will be the biggest solar-thermal project in the world, producing 392 megawatts of electricity–enough to power 140,000 homes in California. Ivanpah will be as different from the rooftop panels that most of us associate with solar power as a modern coal plant is from a basement boiler. Instead of converting sunlight directly into electricity, as a photovoltaic module does, Ivanpah will harness the sun to generate heat and use that to create electricity. Given the vast amount of desert land that gets reliable year-round sunshine, solar-thermal technology could be the fastest way for renewable energy to scale up. It will be able to generate reliable base-load power, the day-to-day, background level of electricity that utilities must have to function and which other renewable sources like traditional solar panels and wind-power programs have struggled to provide. Ivanpah–$2.2 billion and some four years in the making–will be the proving ground. Says David Crane, CEO of NRG Energy, a Princeton, N.J.–based energy company that’s a major investor in Ivanpah: “It’s a huge step for California and the world.”
Ivanpah may be a landmark for renewables, but the technology behind it is surprisingly straightforward. It generates electricity the same way a conventional power plant does, by harnessing heat. The mirrors, known as heliostats, concentrate the sun’s energy on a solar tower, which contains water. The gathered sunlight turns the water into superheated steam, which is piped to a turbine at the base of the tower to generate electricity. Desert sunlight does the work that a coal- or natural-gas-fired furnace does in a conventional plant–except that Ivanpah produces no carbon emissions and no pollution. And while Ivanpah won’t be the world’s first solar-thermal plant, it will be the biggest, thanks in part to its solar-tower design. (Most earlier solar-thermal plants use a parabolic-trough design, where curved mirrors focus sunlight on a pipe that extends the length of the trough, heating fluid that is then used to create steam.) The tower design enables the plant to generate electricity more efficiently than other forms of concentrated solar power. “Ivanpah is going to double the global capacity of solar thermal in a single step,” says Shannon Eddy, executive director of the Large-Scale Solar Association.
For Ivanpah, however, timing was as important as technology. It’s virtually impossible for a new renewable-energy project to compete against cheaper, and dirtier, fossil fuels without some initial help. Earlier attempts at solar-tower plants failed largely because that help wasn’t there. But Ivanpah’s backers–including Google, which invested $168 million–have benefited from steadfast public support. Along with more controversial loans to energy start-ups like Solyndra, the 2009 stimulus package included significant loan guarantees for large-scale solar plants that could cover as much as 80% of a project’s construction costs, as well as cash grants. Without that public support–which included a $1.6 billion government-backed loan–ground might never have been broken on Ivanpah. It helps as well that the investors behind Ivanpah were guaranteed contracts from California utilities for the power produced by the plant–power for which those utilities will pay more per megawatt than the average price of electricity to compensate for solar thermal’s higher costs.
But even with a boost from California, Ivanpah faced major challenges, including opposition from environmentalists who would usually be in favor of expanded renewable energy. Ivanpah was sited on federal territory controlled by the Bureau of Land Management (BLM), which had never been involved with a solar project of this size. Developers tried to minimize the impact on the desert as they built the towers and installed the 173,000 heliostats, limiting grading of the land and keeping concrete foundations to a minimum. Because the mirrors rest on poles several feet aboveground, most of the terrain in the solar fields has remained in its natural state.
But the real challenges came when biologists discovered that more than 150 threatened desert tortoises were living on the construction site. The tortoises are protected by the Endangered Species Act, and the government responded by shutting down the multibillion-dollar project for a few months until a plan could be formulated to relocate the animals. The tortoises were eventually moved, albeit at a cost of more than $50 million, adding to the overall bill for the plant. “Ivanpah became a symbolic flash point of the perceived conflict between clean energy and wildlife habitat,” says Brendan Cummings, senior counsel at the Center for Biological Diversity, an environmental group based in Tucson, Ariz. “But the companies and BLM have learned from this, and future projects should be built in less sensitive areas.”
The need for conservation isn’t the only lesson that will be taken from Ivanpah. Construction of the plant was a massive undertaking involving over 45 million separate parts. BrightSource, the solar-technology developer, and Bechtel Power, the company chiefly responsible for building Ivanpah, developed methods to carry out much of the manufacturing at the construction site–techniques that will be useful the next time a similar plant is built. At a hangar-size facility in the heart of the site, a robot arm plucks from a stack the mirrors that make up the heliostats–each the size of a garage door–and moves them down the assembly line, where workers attach motors that will angle them to catch the sun over the course of a day. From there the heliostats are trucked out to the fields circling the three solar towers, where they’re hammered into the ground. “I’m proud of what we’ve been able to do,” says Alasdair Cathcart, the president of Bechtel Power. “Now we need to work to bring the costs down to make solar more competitive.”
The big economic question is whether solar-thermal projects like Ivanpah can compete effectively against cheaper fossil fuels–or, for that matter, the more familiar solar photovoltaic (PV) technology. Since construction began on the plant in 2010, the price of PV modules has plummeted thanks to technological advances and a glut of cheap panels, many manufactured by state-supported firms in China. That’s made solar PV increasingly popular: more than 3.3 gigawatts of solar PV capacity was installed in the U.S. last year, as the average cost of a completed system dropped by 27%. “It’s more difficult to make the case for large-scale solar thermal when PV has gotten so cheap and will keep getting cheaper,” says Jenny Chase, the head of solar analysis for Bloomberg New Energy Finance, a clean-tech market-research firm.
Still, large-scale solar has its advantages. The electricity that will be produced by Ivanpah throughout the day will be much more predictable than that generated by a PV panel. The boiler in the solar tower will stay hot–and keep generating steam and electricity–even if the sun disappears behind the clouds for a few hours, while PV panels stop generating electricity when sunlight dims. Future solar-thermal plants may also have the ability to store excess heat generated during the day, possibly through tanks of molten salt, allowing them to keep producing electricity into the evening.
NRG’s Crane believes that the future of the power industry will ultimately be solar PV distributed on rooftops, largely because a more decentralized system can bounce back much more quickly after a disrupting event like Hurricane Sandy, which knocked out power to millions for weeks. But in the meantime, utilities need base-load power plants that don’t generate greenhouse gases–plants like Ivanpah. “It will probably take 25 years for that change, but utilities can’t wait 25 years without new and cleaner infrastructure,” Crane says.
That’s especially true for sun-drenched regions like the Middle East that are still building up their national power grids. Abu Dhabi opened a 100-megawatt solar-thermal plant earlier this year, and Saudi Arabia is looking to invest more than $100 billion in solar. If all goes well, Ivanpah will be supplying electricity to the grid in California before the end of the year, with all three solar towers lit up like the world’s biggest lightbulbs. Try not to look.
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