Soaking in the sun

The American industry is pushing for a new lease of life to solar thermal power technology. As a first step in this direction, Solar One, a solar thermal power project located in California is being renovated (Solar Today, Vol 9, No 2).

The Luz International Company which set up and operated the Solar One plant near Barstow in the Mojave desert in California, had filed for bankruptcy in 1991 because of the withdrawal of tax credits and incentive by the government. Nevertheless, the plant continued to be operated by a new consortium. and the US government now claims that the project is viable.

Technological modifications are being carried out in Solar One and it has been renamed as Solar Two. The 10 mw advanced solar thermal power plant would meet the power needs of 5,000 people. The US $48.5 million project would be managed by Southern California Edison which leads a consortium of utilities, government agencies and research organisations. The US department of energy will provide 50 per cent of the funding.

Solar thermal power plants use sunrays to heat a fluid from which heat transfer systems are used to generate steam from which drives a generator. There are 3 main types of systems in use for concentrating and collecting diffused sunlight: the parabolic trough, of which about 350 mw peak capacity has been set up in southern California, the parabolic dish, and the central receiver. The central receiver system is the most recent of the 3 and claimed to be the most efficient.

Solar Two will draw its energy by using the central receiver system - focusing sun's rays through 1926 heliostats, each made up of multiple suntracking mirrors, on to a central tower. Energy from the central tower will heat molten salts that can be stored for use when electrical power is required.

Solar Two is expected to become operational by early 1996. With the experience gained from these project, the US Dept of Energy expects that the utilities will be setting up as many as 4 central receiver plants each of 100 mw capacity by 1997-98.

rays to heat a fluid from which heat trans- With promise of this new technology multinational companies, the Indian ministry of nonconventional energy sources has also been trying to get World Bank assistance to set up an experimental solar thermal power plant in Rajasthan.