Trough solar thermal power generation for solar thermoelectric conversion

Trough solar thermal power generation for solar thermal power conversion

Low-temperature solar thermal power generation usually uses flat-plate collectors or flat-cylindrical parabolic collectors to collect heat to obtain heat of about 100°C, and then generate low-boiling steam through low-temperature media (Freon, isobutane, etc.), and use this steam to drive the steam turbine generator set to generate electricity. There is also the use of solar pond heat storage to generate electricity, which also belongs to low-temperature solar thermal power generation.

In the mid-1980s, after a technical summary of the completed solar thermal power station, people believed that although solar thermal power generation is technically feasible, the investment is too large (US$142 million in the US Sun 1 power station) and it is very difficult to reduce the cost. Therefore, all countries have changed their original plans, and the construction of solar thermal power stations has gradually fallen into the cold. Just when people doubted solar thermal power generation, Luz Solar Thermal Power International Co., Ltd., a joint formation of the United States and Israel. Since 1980, it has been conducting research on solar thermal power generation technology, mainly developing trough solar thermal power generation systems. After 5 years, it miraculously entered the commercialization stage.

The trough-type condenser mirror focuses the sunlight on a line, and a tubular heat collector is installed on this focusing line to absorb the focused solar radiation energy. After the fluid in the tube is heated, it flows through the heat exchanger to heat the working fluid, and generates electricity by means of the steam power cycle. The parabola faces the sun for one-dimensional tracking (the device is placed north-south on the axis of the device, and then it rotates east-west to track), the concentration ratio is between 10 and 100, and the temperature range can reach 400°C. The thermal power generation system of this structure was developed in the mid-1980s. So far, a 354 MW trough concentrating thermal power station has been installed in California. The working medium is heat transfer oil. The heat transfer oil can generate 390 ℃ superheated steam through a heat exchanger to drive a steam turbine to generate electricity. This system was developed by the American LUZ company. Since 1984, a variety of systems of 14, 30 and 80 MW have been developed, with a total installed capacity of 354 MW. From 1985 to 1991, the company built 9 trough solar thermal power stations in the California desert, with a total installed capacity of 353.8 MW. The investment in the power station was reduced from US$5,976/kW for No. 1 power station to US$3,011/kW for No. 8 power station. The cost of power generation has dropped from 26.5 cents/kWh to 8.9 cents/kWh. The company is full of confidence and plans to build a trough solar thermal power station with an installed capacity of 800MW in California by 2000, and the cost of power generation will be reduced to 5-6 cents/kWh. Regrettably, the plan was interrupted by the bankruptcy of Luz in 1991.

Trough solar thermal power generation for solar thermal power conversion
Schematic diagram of trough solar thermal power generation

The successful practice of Luz Thermal Power Station shows that the technology of solar thermal power generation cannot be simply denied, but should continue to be researched and developed, and constantly improved, so that it can be commercialized as soon as possible. To this end, several companies from Israel, Germany and the United States have cooperated to continue to promote the development of solar thermal power generation. They plan to build two 80 MW trough solar thermal power stations and two 100 MW solar and gas turbine combined cycle power stations in the United States. Construction of 135 MW and 18 MW solar thermal power plants in Spain and Morocco.