Solutions for Photothermal(CSP) Power Generation
Concentrated Solar Power (CSP) systems generate electricity by using mirrors or lenses to concentrate a large area of sunlight, or solar thermal energy, onto a small area. The concentrated heat is then used as a heat source for a conventional power plant. CSP technology is notable for its ability to store and dispatch energy on demand, especially when integrated with thermal energy storage systems. Here are more detailed examples of CSP technologies and their applications:
1. Parabolic Trough Systems
Parabolic trough systems consist of long, curved mirrors that focus sunlight onto a receiver tube running along the focal line of the parabola. A heat transfer fluid (HTF) flowing through the tube absorbs the concentrated solar energy, heating up to high temperatures. This heat is then used to produce steam, driving a turbine connected to a generator for electricity production. Examples include the SEGS (Solar Energy Generating Systems) plants in California, the largest group of CSP plants in the world.
2. Central Tower Systems (Solar Towers)
In central tower systems, a large field of flat, moveable mirrors called heliostats concentrates sunlight onto a receiver at the top of a tall tower. The concentrated sunlight heats a fluid or molten salt to very high temperatures. The heat is then used to generate steam for electricity production or stored for later use. An example is the Ivanpah Solar Power Facility in the Mojave Desert, which is one of the largest solar thermal power plants globally.
3. Parabolic Dish Systems
Parabolic dish systems use a dish-shaped reflector to concentrate sunlight onto a receiver located at the focal point of the dish. The receiver absorbs the concentrated solar energy, converting it into heat, which then drives a generator directly. These systems can achieve very high temperatures and efficiencies. The Stirling Energy Systems (SES) Solar Dish project is a notable example, where dishes are equipped with Stirling engines for direct conversion of heat into mechanical energy.
4. Linear Fresnel Reflector (LFR) Systems
LFR systems employ an array of flat or slightly curved mirrors to concentrate sunlight onto elevated receivers, which contain the HTF. This design is similar to parabolic troughs but uses simpler and cheaper flat mirrors. The compact arrangement allows for more efficient land use and easier integration into existing industrial sites. The Puerto Errado 2 power plant in Spain is an example of an operational LFR CSP plant.
5. Integrated Solar Combined Cycle Systems (ISCCS)
ISCCS combine CSP technology with conventional natural gas-fired power plants. Solar energy is used to supplement or pre-heat the steam needed for the turbine, increasing the plant’s efficiency and reducing fossil fuel consumption. The Ain Beni Mathar Plant in Morocco is an example, integrating a parabolic trough array into a combined cycle system.
6. CSP with Thermal Energy Storage (TES)
Many CSP plants are now designed with thermal energy storage, allowing them to continue generating electricity even when the sun is not shining. Molten salt is commonly used as a storage medium due to its high heat capacity and ability to store thermal energy efficiently. The Solana Generating Station in Arizona, USA, uses molten salt storage to provide up to 6 hours of full power after sunset.
CSP technologies offer versatile solutions for solar power generation, capable of delivering renewable energy on demand through direct generation or thermal storage. From parabolic troughs and central towers to innovative integrated systems, CSP plants can provide scalable, dispatchable solar energy, contributing significantly to global renewable energy portfolios and helping to stabilize and decarbonize the energy grid.