CSP and ISCC (Integrated solar combined cycle) plants must be located in areas of high insolation that are usually arid.

This lack of water prevents the use of efficient direct or wet cooling. A powerful example of the limitation of water cooling on the potential of CSP is the 250 MW Beacon Solar Energy project, the first solar thermal power plant to be licensed in California in nearly 20 years.  The approval process required a solution to local residents’ objections to the great amount of water the project would require. The final agreement will have the project use recycled water from a nearby community instead of drawing directly from the local aquifer. The project expects to use nearly 1.97 million cubic meters of water annually.

The alternative of dry cooling with air-cooled condensers, shown in the diagram below, is expensive and leads to lower cycle efficiencies.  This is due to the parasitic electrical load that dry cooling places onto the plant.

A schema for a typical CSP plant with dry cooling

In addition, conventional CSP and ISCC plant output is limited by the availability of the sun leading to expensive investment in thermal storage devices, such as molten salts, to extend the period of generation beyond the hours of sunshine.  Investment in storage typically increases plant development costs by 30%(FN5).

FN5 – Emerging Energy Research – Global CSP report, 2007