How to harness and use the energy of the sun? This is a question humanity has been asking itself for many years. One way to use the energy of our nearest star is solar panels, which are now commonly installed on the roofs of houses. However, panels are not the only way to use the sun to generate energy. Another method has been known for a long time, which has an additional advantage over panels because it can store energy. Now the Chinese are interested in it. Does this mean that CSP technology will get a second chance?
A stain on the image of the CSP power plant
The first large CSP power plant was built in 1981 in California. At that time, this technology was more promising than photovoltaics.
Later, further projects were developed, including the Crescent Dunes solar power plant, located near Las Vegas. The megaproject, consisting of thousands of mirrors arranged in concentric circles and staring at a huge concrete pillar rising 195 meters, was completed in 2015. The power plant was to generate electricity for 75,000 people. houses.
Unfortunately, the billion-dollar project that was supposed to be a breakthrough for concentrated solar power technology fell short of expectations and instead of paving the way for a wave of other CSP projects, it damaged the image of the technology. There was too little energy, and after repeated technical failures and prolonged work interruptions, the plant was closed in 2019.
China’s interest
There are currently only about 7 gigawatts of CSP power plants in the world, mostly in places with lots of direct sunlight such as Spain, the US, Chile, Morocco and the United Arab Emirates. Meanwhile, installed global photovoltaic capacity now exceeds 2,000 gigawatts.
Now China is interested in CSP technology and is building 30 power plants concentrating solar rays. Does this mean a return to CSP. Perhaps so, because this technology has one special feature that distinguishes it from ordinary solar panels. It can store energy and produce electricity when the sun no longer shines.
How CSP works
CSP power plants use solar heat. So-called heliostats, essentially mirrors, reflect and focus sunlight on one specific point. The heat from the concentrated sunlight is then used to produce steam, which turns a turbine that produces electricity.
The entire mirror field must be carefully adjusted to track the movement of the sunthanks to which the light is precisely reflected. This allows you to control the temperature of the liquid circulating in the system.
In the case of the Crescent Dunes project, the sun’s rays are focused on the top of the solar tower. The liquid inside this receiver is heated to turn steam turbines to produce electricity, and then pumped back to the tower for reheating. Molten salt is usually used as the liquid because it is particularly good at retaining heat.
CSP can also generate electricity at night
CSP lost the technology race mainly due to falling prices of semiconductors and photovoltaic panels. Additionally, solar panels are simple to set up and install, while CSP plants are a major engineering project. But despite everything, CSP has one big advantage over photovoltaics. It can also generate energy at night.
Newer power plants usually have large insulated tanks in which hot molten salt can be stored. Inside, it only cools down by about 1 degree Celsius per day, so it can be used to produce steam at a later time. This makes it possible to store energy and convert it into electricity around the clock, which may give CSP a new advantage over photovoltaics.
And experts see energy storage as the reason for the sudden popularity of CSP in China. Many provinces now have laws requiring that each new renewable energy park with a capacity of more than 1 gigawatt had to include at least 10 percent storage.
