One exciting new development solar (thermal) power plants by Greenwish Partners, which is set to start producing electricity by 2018. The largest plant, which is to be set up in Enugu State, is set to produce 100 megawatts of electricity, while the company will build two others of 50MW each in Kaduna and Jigawa states.
But what is it about solar plants?
Let’s do a bit of knowledge drop.
Solar power plants use the sun’s rays to produce electricity. Photovoltaic plants and solar thermal systems are the most commonly used solar technologies today.
There are two types of solar power plants. They are differentiated depending on how the energy from the sun is converted into electricity – either via photovoltaic plants (solar cells) or via solar thermal power plants.
A photovoltaic cell, commonly called a solar cell or PV, is a technology used to convert solar energy directly into electricity. A photovoltaic cell is usually made from silicon alloys. Particles of solar energy, known as photons, strike the surface of a photovoltaic cell between two semiconductors. These semiconductors exhibit a property known as the photoelectric effect, which causes them to absorb the photons and release electrons. The electrons are captured in the form of an electric current – in other words, electricity.
Solar thermal power plants
A solar thermal plant generates heat and electricity by concentrating the sun’s energy. That, in turn, builds steam that helps to feed a turbine and generator to produce electricity.
There are three types of solar thermal power plants:
1) Parabolic troughs: This is the most common type of solar thermal plant. A “solar field” usually contains many parallel rows of solar parabolic trough collectors. They use parabola-shaped reflectors to focus the sun at 30 to 100 times its normal intensity. The method is used to heat a special type of fluid, which is then collected at a central location to generate high-pressure, superheated steam.
2) Solar power tower: This system uses thousands of flat sun-tracking mirrors called heliostats to reflect and concentrate the sun’s energy onto a central receiver tower. The energy can be concentrated as much as 1,500 times that of the energy coming in from the sun.
3) Solar pond: This is a pool of saltwater which collects and stores solar thermal energy. It uses so-called salinity-gradient technology. Basically, the bottom layer of the pond is extremely hot – up to 85 degrees Celsius – and acts as a transparent insulator, permitting sunlight to be trapped from which heat may be withdrawn or stored for later use. This technology has been used in Israel since 1984 to produce electricity.