Concentrating Solar Power

Concentrating solar power creates electricity by generating heat using mirrors to concentrate the sun's rays. The most common, least expensive form of concentrating solar power is generated through parabolic troughs. These focus sunlight onto a central pipe to heat fluid to around 400 degrees Centigrade. The heat then creates steam to drive a traditional turbine.

A second form of concentrating solar power comes from solar dishes. These focus sunlight onto a single point to create heat. A third form of concentrating solar power comes from solar towers. These use a circular field of mirrors to focus sunlight on a central tower to create heat.

Parabolic troughs
Solar dish
Solar tower

In all three technologies, excess solar-generated heat collected during the peak midday period can be stored temporarily in salts and oils and drawn down later in the day to generate energy. This "battery" function enables concentrating solar power to continue to create electricity after sundown by drawing down on its thermal reserves. Such thermal reserves also can be brought on line instantaneously to meet afternoon peak loads, which are short-lived periods of high electricity consumption that drive up electricity costs across the board. Having an available, low-cost means of meeting this demand increases grid stability and lowers costs.

Small-scale solar thermal storage tanks in Spain
Concentrating solar power generation synchronizes well with grid demand. It can "store" power in the morning, "double up" power generation during the afternoon peak and "draw down" storage in the evening.

It's Here. It's Now. It Works. It Has Been For 20 Years

In the early 1980s US President Jimmy Carter encouraged alternative and renewable energy production with investment and production tax credits. In response, Luz Solar Partners Ltd. built nine parabolic trough power plants in California ranging in size from 13.8 MW to 80 MW and totaling 354MW of capacity. All still operate today. They remain the largest collection of concentrating solar power plants in the world.

California parabolic troughs
Parabolic troughs in California have been providing a constant, reliable stream of solar energy now for more than 20 years.
California parabolic troughs
Source: Schott Solar

With energy prices high and climate change now threatening humanity's quality of life, concentrating solar offers the single best renewable energy solution to the climate change problem. The land is available, the feedstock is free and the technology is scalable, proven, simple and getting cheaper by the day. Given this, money is now flowing into concentrating solar power.

The two main centres of activity at present are Spain and California. In those two locations, large commercial projects are under construction. As more plants get built, economies of scale occurs and research and development breakthroughs compound, concentrating solar power is expected to fall to around 5-6 Australian cents per kilowatthour by 2015, probably earlier. That will be less than nuclear or carbon capture and storage when coal and nuclear are properly costed.

Research and development advances, manufacturing efficiencies and
increasingly scaled-up concentrating solar power plants are
expected to halve prices within 10-15 years.

The reason that concentrating solar power is falling so rapidly is due to accumulated experience, research and development and increasing scale. The price declines forecast above are predicated upon 2,000MWs of capacity being installed between now and 2015. Roughly 3,000MWs of capacity are currently undergoing permitting in California alone, indicating that the rollout could exceed expectations. This is not unusual with new technologies. For instance, take wind. In the 1980s, the International Energy Agency forecast a slow but steady uptake in wind technology. They were off, hugely. Installation of wind technology turned out to be several times their expectations. It's likely to be the same with concentrating solar power. In fact, it already is.

Estimates of the pace of rollout of wind capacity worldwide
proved short of the mark. It will prove the same with solar
Source: World Bank