By Jonathan G. Dorn, Earth Policy Institute, USA

WASHINGTON, D.C. – After emerging in 2006 from 15 years of hibernation, the solar thermal power industry experienced a surge in 2007, with 100 megawatts (MW) of new capacity coming on-line worldwide. During the 1990s, cheap fossil fuels, combined with a loss of state and federal incentives, put a damper on solar thermal power development. However, recent increases in energy prices, escalating concerns about global climate change, and fresh economic incentives are renewing interest in this technology.

Considering that the energy in sunlight reaching Earth in just 70 minutes is equivalent to annual global energy consumption, the potential for solar power is virtually unlimited. With concentrating solar thermal power (CSP) capacity expected to double every 16 months over the next five years, worldwide installed CSP capacity will reach 6,400 MW in 2012--14 times the current capacity. (See data at http://www.earth-policy.org/Updates/2008/Update73_data.htm#table1.)

Unlike solar photovoltaics (PV), which use semiconductors to convert sunlight directly into electricity, CSP plants generate electricity using heat. Much like a magnifying glass, reflectors focus sunlight on to a fluid-filled vessel. The heat absorbed by the fluid is used to generate steam that drives a turbine to produce electricity.

Power generation after sunset is possible by storing excess heat in large, insulated tanks filled with molten salt. As CSP plants require high levels of direct solar radiation to operate efficiently, deserts make ideal locations.

Two big advantages of CSP over conventional power plants are that the electricity generation is clean and carbon-free and, as the sun is the energy source, there aren’t any fuel costs. Energy storage in the form of heat is significantly cheaper than battery storage of electricity, providing CSP with an economical means to overcome intermittency and deliver dispatchable power.

The USA and Spain are leading the world in the development of solar thermal power, with a combined total in excess of 5,600 MW of new capacity expected to come on-line by 2012. Representing more than 90% of the projected new capacity by 2012, the output from these plants would be enough to meet the electrical needs of more than 1.7 million homes.

Plants coming on-line

The largest solar thermal power complex in operation today is the Solar Electricity Generating Station in the Mojave Desert in California. Coming on-line between 1985 and 1991, the 354 MW complex has been producing enough power for 100,000 homes for almost two decades. In June 2007, the 64 MW Nevada Solar One plant became the first multi-megawatt commercial CSP plant to come on-line in the USA in 16 years.

Today, more than a dozen new CSP plants are being planned in the USA, with some 3,100 MW expected to come online by 2012. (See data at http://www.earth-policy.org/Updates/2008/Update73.htm#table6.) Some impressive CSP projects in the planning stages include the 553 MW Mojave Solar Park in California, the 500 MW Solar One and 300 MW Solar Two projects in California, a 300 MW facility in Florida, and the 280 MW Solana plant in Arizona.

In Spain, the first commercial-scale CSP plant to begin operation outside the USA since the mid-1980s came on-line in 2007: the 11 MW PS10 tower. The tower is part of the 300 MW Solúcar Platform which, when completed in 2013, will contain ten CSP plants and produce enough electricity to supply 153,000 homes while preventing 185,000 tons of carbon dioxide (CO2) emissions annually. All told, more than 60 plants are in the pipeline in Spain, with 2,570 MW expected to come on-line by 2012.

Feed-in tariffs

Economic and policy incentives are partly responsible for the renewed interest in CSP. The incentives in the USA include a 30% federal Investment Tax Credit (ITC) for solar through the end of 2008, which has good prospects for being extended, and Renewable Portfolio Standards in 26 states.

California requires that utilities get 20% of their electricity from renewable sources by 2010, and Nevada requires 20% by 2015, with at least 5% from solar power. The primary incentive in Spain is a feed-in tariff that guarantees that utilities will pay power producers €0.26 (40¢) per kilowatt-hour for electricity generated by CSP plants for 25 years.

In the southwestern USA, the cost of electricity from CSP plants (including the federal ITC) is roughly 13–17¢ per kilowatt-hour, meaning that CSP with thermal storage is competitive today with simple-cycle natural gas-fired power plants. The U.S. Department of Energy aims to reduce CSP costs to 7–10¢ per kilowatt-hour by 2015, and to 5–7¢ per kilowatt-hour by 2020, making CSP competitive with fossil-fuel-based power sources.

Outside the USA and Spain, regulatory incentives in France, Greece, Italy, and Portugal are expected to stimulate the installation of 3,200 MW of CSP capacity by 2020. China anticipates building 1,000 MW by that time. Other countries developing CSP include Australia, Algeria, Egypt, Iran, Israel, Jordan, Mexico, Morocco, South Africa, and the United Arab Emirates. (See map at http://www.earth-policy.org/Updates/2008/Update73_data.htm#fig7.)

Using electric vehicles

Using CSP plants to power electric vehicles could further reduce CO₂ emissions and provide strategic advantages by relaxing dependence on oil. In Israel, a tender issued by the Ministry for National Infrastructures for the construction of CSP plants and a 19.4¢ per kilowatt-hour feed-in tariff for solar power systems are sparking interest in developing up to 250 MW of CSP in the Negev Desert. This would produce enough electricity to run the 100,000 electric cars that Project Better Place, a company focused on building an electric personal transportation system, is planning to put on Israeli roads by the end of 2010.

A study by Ausra, a solar energy company based in California, indicates that more than 90% of fossil fuel–generated electricity in the USA and the majority of the country’s oil usage for transportation could be eliminated using solar thermal power plants – and for less than it would cost to continue importing oil.

The land requirement for the CSP plants would be roughly 38,850 square kilometres, the equivalent of 15% of the land area of Nevada). While this may sound like a large tract, CSP plants use less land per equivalent electrical output than large hydroelectric dams when flooded land is included, or than coal plants when factoring in land used for coal mining.

Another study, published in Scientific American in January 2008, proposes using CSP and PV plants to produce 69% of USA electricity and 35% of total USA energy, including transportation, by 2050.

The DESERTEC Concept

CSP plants on less than 0.3% of the desert areas of North Africa and the Middle East could generate enough electricity to meet the needs of these two regions and the European Union. Realising this, the Trans-Mediterranean Renewable Energy Co-operation – an initiative of The Club of Rome, the Hamburg Climate Protection Foundation, and the National Energy Research Centre of Jordan –conceived the DESERTEC Concept in 2003.

This plan to develop a renewable energy network to transmit power to Europe from the Middle East and North Africa calls for 100,000 MW of CSP to be built throughout the Middle East and North Africa by 2050. Electricity delivery to Europe would occur via direct current transmission cables across the Mediterranean. Taking the lead in making the concept a reality, Algeria plans to build a 3,000-kilometre cable between the Algerian town of Adrar and the German city of Aachen to export 6,000 MW of solar thermal power by 2020.

If the projected annual growth rate of CSP through 2012 is maintained to 2020, global installed CSP capacity would exceed 200,000 MW – equivalent to 135 coal-fired power plants. With billions of dollars beginning to flow into the CSP industry, and USA restrictions on carbon emissions imminent, CSP is primed to reach such capacity.

For more information on Earth Policy Institute’s goal of 200,000 MW of CSP worldwide, part of a plan to cut carbon emissions 80% by 2020, see Chapters 11–13 in Plan B 3.0: Mobilising to Save Civilization, available at www.earthpolicy.org for free downloading.