California Looks at Renewable Future
on the edge of the Mojave Desert north of Los Angeles, 24,000 mirrors track the Sun’s progress across a clear, blue sky. The neat ranks of heliostats and the computer algorithm that moves them make the Sierra SunTower plant a focal point for a novel type of power generation and a new wave of energy companies looking to turn the search for renewables into successful businesses.
Solar tower technology uses mirrors to reflect sunlight on to a thermal receiver atop a tower. The reflected sunlight boils water inside the receiver to create superheated steam at 440C (824F), which drives a turbine and generates electricity.
The plant is a demonstration facility built by eSolar, one company among dozens in California aiming to heed President Obama’s call for a new energy industry that is less reliant on fossil fuels. ESolar, which is based in Pasadena, started less than three years ago and has gathered $170 million (£107 million) of investment, including funding from Google, in its attempt to make solar power mainstream.
The Sierra SunTower facility features two 190ft (58m) towers surrounded by 20 acres (8ha) of mirrors in neat rows that stand at about chest height. The five-megawatt plant produces electricity for Southern California Edison (SCE) and can power more than 4,000 homes. Each one-metre-square mirror, or heliostat, sits on a mechanism that allows computer software to move it in precise increments, so that it is always at an optimal angle to reflect the Sun’s ray’s on to the thermal receiver.
ESolar claims that its tracking software makes the plant far more efficient than previous technologies for concentrating solar power. The company says that its prefabricated modular designs have solved many of the problems that have held back large-scale solar generation, includ-ing cost, speed of deployment and proximity to existing transmission lines.
In particular, it says that the lightweight mirrors need much less steel and concrete to set them in place, which reduces construction costs. The company touts the Sierra SunTower model as one that can be replicated anywhere that the Sun shines, on industrial sites or on uneven ground, and is looking to franchise out its technology to other companies to build and run solar power plants.
Bill Gross, the chief executive of eSolar, said: “Sierra is just the beginning. Soon eSolar technology will be deployed worldwide to provide clean, affordable energy to hundreds of thousands of homes. We’re at an historic point when technology can finally enable clean, renewable energy at a price competitive with fossil fuels.”
In February eSolar announced an agreement with NRG Energy to develop three plants in California and New Mexico that will generate up to 465MW of electricity. The first plant is expected to come onstream in 2011.
ESolar is also looking overseas. India, in particular, has ambitious plans for solar power generation and, in March, the company licensed its technology to ACME Group, which is based there, for approximately one gigawatt of solar thermal capacity. Its first 2.5MW plant is under construction in Rajasthan and the installation of a 46MW plant is likely to begin in 2010 for completion in 2011. India boasts arguably the most ambitious solar energy development plan in the world, with a target of 20,000MW for 2022. The country has excellent solar resources, particularly in the northwest.
Raed Sherif, eSolar vice-president of international development, said that the business was in talks with companies in Jordan, Kuwait and Egypt and had opened an office in South Africa.
The US Energy Department has calculated that a 62-square-mile (160 sq km) parcel of the Mojave that straddles Nevada, Utah, California and Arizona receives enough sunlight to power the entire country. In Lancaster, the site of the eSolar facility, there are about 300 sunny days a year and the company says tests indicate that the plant works even on partially cloudy days.
Other Californian start-up companies are getting in on the act. BrightSource Energy, based in Oakland, has contracts with Pacific Gas & Electric and Southern California Edison for its Ivanpah plants, with a capacity of 440MW in the Mojave. Bechtel, the huge American project-management specialist, has signed on as the engineering contractor and equity partner for the project. BrightSource is also constructing a 29MW thermal plant for Chevron in Coalinga, California, and the company has operations in Israel and Australia. Arnold Schwarzenegger, the Governor of California, has become a keen supporter of solar power generation in the Mojave and has fostered legislation to cut carbon emissions and tackle climate change. Last month he mandated that, by 2020, at least 33 per cent of state energy comes from renewable sources.
In all categories of solar power generation, including photovoltaic, the United States ranks fourth, after Germany, Spain and Japan, producing about 8,800MW last year, according to the Solar Energy Industries Association, or less than 1 per cent of America’s energy use.
President Obama has called for that figure to rise substantially. In all, $80 billion of stimulus grants has been spent to jump-start clean-tech industries such as solar thermal. The American Solar Energy Society has forecast that a shift to renewable sources could create as many as 37 million jobs by 2030.
Global solar industry leaders went to Copenhagen this month to highlight the impact that solar energy technologies can have on combating climate change. Solar arrays leave no carbon footprint after manufacture of components and construction.
However, the ultimate aim of achieving “parity” with fossil fuel power production — when it is as cheap to make electricity from solar sources as from coal — is still some way off, according to experts.