Solar Thermal Power Generation

Thermal power generation is one of the important projects in utilizing solar energy. So long as rays of the sun is concentrated to heat the actuating medium driving the steam turbine generator, electricity is produced.

In 1950, former Soviet Union designed the first set of solar energy tower type power station in the world and constructed a small pilot device. In the 1970s, due to the reason that solar cells were expensive and low efficient while thermal power generation was higher in efficiency and mature in technologies, many industrial countries turned their focus towards thermal power generation and input investment to build a batch of pilot thermal power stations. According to incomplete statistics, the worldwide thermal power stations, which were built from 1981 to 1991, exceeded 20 sets with the max. capacity of 80MW.

If classified according to concentrating method, thermal power stations have 3 types including tower, trough and dish type. All of the power stations are belonging to pilot stations. For example, in accordance with the sunlight programme, Japan constructed one set of 1MW tower type power station and one set of 1MW trough type power station, which was out of action after commissioned. After being commissioned for a period and technically summarized, Solar No.1 10MW tower type power station in the US was reconstructed to be Solar No.2 power station, which was put into operation in January 1996.

In the middle of the 1980s, after technically summarized on the built thermal power station, it was generally agreed that the investment was too large in amount (142 million US dollars for Solar No.1) and difficulty to reducing the cost, although its technology was feasible. As a consequence, all of the country changed their original plans following with the absent treatment on solar energy project. For example, the US has once scheduled to build solar thermal power stations with capacity of 50,000 to 100,000kW and 100,000 to 300,000kW from the year of 1983 to 1995, but failed to realize.

Just when people were doubtful of the solar thermal power generation technology, Routs solar thermal power generation international Co. Ltd jointly organized by the US and Israel, started to conduct the research on thermal power generation technologies from 1980, preferentially developing trough type generation system which was against nature to enter into the commercialization stage. The company has built 9 sets of trough type thermal power station with the total installed capacity of 353.8MW in the desert region in California from 1985 to 1991. The investment on power stations declined from $5976/kW in No.1 station to $3011/kW in No.8 station. The generation cost decreased from 26.5 cents/kWh to 8.9cents/kWh. The company was in full confidence in scheduling to build a trough type power station with the installed capacity accounting for 800MW in California in 2000, with the generation cost down to 5 to 6 cents/kWh. But unfortunately, the schedule was broken down due to the bankruptcy of the company.

The successful implementation of Routs thermal power station showed that thermal power generation technologies couldn¡¯t be denied simply, of which research and development should be continued and improved so as to realize its commercial benefits at an early state. For this purpose, several companies from Israel, Germany and the US made a joint cooperation to further promote the development of solar thermal power generation. They scheduled to construct 2 sets of 80MW trough type solar power station and 2 sets of 100MW solar and gas turbine cycle power station in Nevadan, and one of 135MW solar power station in Spain and one set of 18MW solar power station in Morocco respectively.

Dish solar power generation system is lower in efficiency ranging from 5 to 50kW generally, and can be either decentralized or formed larger scale generation system. It has been applied in the US and Australia with small scale.

Research demonstrated that the dish solar power generation system possessed the advantage of lower pneumatic resistance, small blastoff quality and inexpensive operation cost if it was applied to the space comparing with the photovoltaic power generation system. The US has started the feasibility study from 1988 and scheduled to conduct the blastoff experiment recently.

Regarding the lower temperature solar power generation, Israel has built 3 sets of solar tank power stations in the coastal area of the Dead Sea successively, of which the first station was put into operation in 1979 with the capacity of 150kW. Israel has once scheduled to build series of solar tanks around the Dead Sea to provide 1/3 of the total electricity needs. The US has once planned to make part of the Salvadon Sea in California into solar tank by constructing 800,000 to 6 million kW solar tanks. But after that, their schedules on solar tanks were changed.

Except for the above-mentioned solar power generation methods, Spain built a set of exhaust type solar power station in 1983; the US and Israel scheduled to construct solar energy magnetic fluid thermal power generation pilot device; research on seawater temperature difference power generation was developed. The solar thermal power generation technology applicable for small capacity was applied to some special cases including thermal ion power generation and temperature difference power generation.

Due to the limitation on budget and technical condition in the field of solar thermal power generation, China was little involved in the manufacturing. During the sixth five-year period, it has established one set of 1kW tower thermal power generation simulation device and one set of 1kW flat plate lower temperature thermal power generation simulation device. Furthermore, 5kW prototype dish solar power generation device was designed and commissioned under the cooperation of the US and China.