ville
* US (California) - 250 MW FPL Energy's Beacon Solar Energy Project
Feasibility studies are also being done in Oman, China and Mexico.
One of the key differentiating factors between solar thermal power and solar PV is that heat energy is more easily (and efficiently) stored than electricity, with solar thermal plants often combining energy storage into the design to enable around-the-clock, dispatchable electricity generation.
Most solar thermal plants are looking to use molten salt for storing energy - other alternatives being developed are graphite (in the Cloncurry development), heated water / steam (for the Ausra plants) and heat-transfer oil such as therminol (for the Abengoa plant in Arizona).
The existing plants prove that concentrated solar power is practical, but costs must decrease. Electricity from solar thermal plants currently costs between US$0.13 per kilowatt hour (kWh) and US$0.17 per kWh, depending on the location of the plant and the amount of sunshine it receives. Conventional power plants generate electricity for between US$0.05 and US$0.15 per kilowatt hour (not including any carbon taxes or cap and trade related costs) but in most places it's below US$0.10 (wind power generally costs around US$0.08 per kWh).
An economic analysis released last month by Severin Borenstein (pdf), director of the University of California's Energy Institute, notes that solar thermal power will become cost competitive with other forms of power generation decades before photovoltaics will, even if greenhouse-gas emissions are not taxed aggressively.
In 2006 a report by the Solar Task Force (pdf) of the Western Governors’ Association concluded that CSP could provide electricity at US$0.10 per kWh or less by 2015 if 4 GW of plants were constructed.
According to Bernhard Milow from the German Aerospace Center (DLR) electricity from solar thermal plants could cost as little as €0.04 per kWh [US $0.06/kWh] by 2020, with well sited plants potentially generating power at lower prices than coal.
The US DOE began supporting large scale CSP last year, aiming to reduce the cost of CSP power to 7-10¢/kWh by 2015 and 5-7¢/kWh by 2020. The DOE estimated that reaching these cost targets could lead to installation of up to 35,000 MW of new generating capacity by 2030 in the US. James Fraser at The Energy Blog commented at the time that it was 5 years too late (given recent commercial activity in the area) and that PV solar may beat these price goals before solar thermal does, but that more solar options are good in any case, as both PV and thin film solar manufacturing will be constrained by availability for materials for some time as production continues to accelerate.
Another estimate from Sandia labs showed solar thermal costs (for solar towers) could fall to around 4 cents per kWh by 2030.
Another variant on the solar thermal power theme are Stirling engine based power plants, which generate electricity directly rather than first storing the energy as heat.
Stirling Energy Systems seems to be the leader in this field, with some reports talking about agreements with Southern California Edison and San Diego Gas & Electric for up to 1.75 GW of power. The company recently set a new world record of 31.25% for Solar-to-Grid conversion efficiency.
Other companies pursuing stirling engine based solutions are Infinia and SunPower (not to be confused with its larger namesake in the PV industry).
Passive Solar Thermal - Solar Hot Water And Others
Generating power isn't the only way to utilise solar thermal energy of course - solar hot water is a very cheap and efficient way of replacing gas or electricity usage with solar energy. Solar hot water systems are in widespread use in Australia, with state and federal governments encouraging people to upgrade their home hot water systems to solar - almost cost free in some states. The New Zealand government is also encouraging the use of solar hot water systems.
Some larger scale uses of solar thermal hot water are being put in place by Abengoa in Texas and Colorado.
Solar hot water is in wide us