Many power plants today use fossil fuels as a heat source to boil water. The steam from the boiling water spins a turbine, which drives a generator to produce electricity. However, a new generation of power plants with Concentrating Solar Power (CSP) systems uses the sun as a heat source.
A power tower system uses a large field of flat, sun-tracking mirrors known as heliostats to focus and concentrate sunlight onto a receiver on the top of a tower. A heat-transfer fluid heated in the receiver is used to generate steam, which, in turn, is used in a conventional turbine generator to produce electricity. The CSP tower uses water/steam as the heat-transfer fluid, which is called as Direct Steam Generation(DSG),while other uses molten nitrate salt as the fluid because of its superior heat-transfer and energy-storage capabilities. The energy-storage capability, or thermal storage, allows the system to continue to dispatch electricity during cloudy weather or at night.
The main advantages of CSP, including:
● CSP can provide stable and dispatchable electricity output through thermal storage equipment.
● CSP has high system efficiency and can achieve large-scale power generation.
●The thermal-electricity process is similar to conventional thermal power plant, so that CSP can be easily integrated with the conventional
thermal power plant for complementary power generation.
● CSP is genuine green energy with low energy consumption and pollution during the manufacturing process of all its components.
CSP status & prospect
There were 4.9 GW of CSP projects operational worldwide at the end of 2015, and it is the key to achieve a 100% renewables share by 2050.
According to a new report by the European Solar Thermal Electricity Association (ESTELA), Greenpeace International and SolarPACE, the sector is on track towards double digit gigawatt capacity within the next five years, and it could meet up to 6% of the world’s power needs by 2030 and 12% by 2050.
Moreover, the International Energy Agency (IEA) predicted in 2014, that the solar energy will become the first majority electricity sourcing in 2050, while CSP will contribute 11% of the global electricity supplying.
CSP technical routes
The CSP technologies includes Tower, Parabolic Trough, Linear Fresnel, and Dish Stirling, while Tower and Parabolic Trough are the most popular CSP technologies. Parabolic trough technology has more installed capacity, but observers increasingly predict the future will belong to Towers, because of its high concentrating ratio, high system efficiency, low construction and maintenance cost, and high terrain adaptability.