Solar energy is a clean, domestic resource that helps bring efficient, low-cost energy to homes, businesses and industry. Switching to solar power protects the environment by avoiding fuels that release greenhouse gasses. It also helps to improve energy security. Renewable energy that is locally harvested reduces the need for foreign oil, which is often volatile in supply and price.

Solar energy can be harnessed through concentrating solar power (CSP) systems. CSP systems gather sunlight and convert it into electricity. They do this by using mirror technology to focus sunlight onto receivers. The receivers use fluid to convert sun energy into thermal energy. The heat energy then activates a turbine or engine to crank a generator and create electricity. CSP systems can be scaled up to large plants to provide mass electricity reserves to communities.

Common CSP systems include linear concentrator systems, dish-engine systems and power tower systems. Take a closer look at the technology behind these systems, and learn how CSP components work together to deliver sun-powered solutions

Linear Concentrator Systems

In linear CSP fields, mirrors transfer sunlight to a receiver tube. Inside the tube is a fluid. As the fluid gets heated by the sun, it generates steam. The steam then turns a turbine. As the turbine blades spin, they rotate a crank, which activates a generator. The generator then produces electricity.

Linear CSP systems commonly use a parabolic trough system design, where mirrors are curved around receiver tubes. These systems may also have thermal storage tanks that store sun-heated fluid. This provides the convenience of use during times of low sunlight. Hybrid designs, which use gas-powered heaters or boilers to supply supplemental power, may also be combined with trough schematics.

Some linear concentrating solar power systems use a Fresnel design. In this setup, the sun hits Fresnel reflectors on the ground. Heat energy is then transferred up to tube receivers that are elevated above the reflectors.

Dish-Engine Systems

Dish-engine systems use solar concentrators and power conversion units to generate electricity. The solar concentrators are parabola-shaped dishes that reflect beams of sunlight to power conversion units. Tracking mechanisms allow the dishes to follow the sun’s path for maximum efficiency.

In the power conversion unit, the thermal receiver collects the heat from the sunbeam and transfers the thermal energy to the engine. The engine converts the thermal energy to mechanical energy, which then drives the generator to produce electricity. A dish-engine system can generate up to 25 kilowatts of electricity.

Power Tower Systems

In power tower systems, heliostats (flat mirrors that track the sun) focus sunlight up to a receiver sitting atop a tower. The receiver holds water, steam or heat-transfer fluid. From the receiver, the heated fluid either enters a storage tank or a steam condenser, before flowing to a turbine as steam. The steam forces the turbine’s blades to spin, which then cranks a generator and produces electricity. From the generator, the electricity enters the power grid. Large-scale power tower plants can generate up to 200 megawatts of electricity.

Photo: Sun by Bruno_Caimi licensed under Creative Commons 4.0