The wide spread adoption of solar energy has been handicapped because of the lack of electrical storage capabilities. The solar industry is still far from a comprehensive storage solution, but there is a glimmer of hope on the horizon. A relatively new solar energy technology called concentrating solar power (CSP) is starting to be built out for commercial electricity production. CSP is a solar niche market that holds much promise for the advancement of the solar industry and the renewable energy sector as well. In this article, we will discover how concentrating solar power (CSP) works; the benefits it brings, and why it is important to solar and renewable energy proponents.
Concentrating Solar Power
A CSP power plant uses mirrors to concentrate sunlight on pipes or plates which contain a heat transfer fluid. This fluid then passes through a heat-exchanger creating steam to run the electrical generation turbines. This technology can be used with or without thermal energy storage. Most of the new plants are incorporating thermal storage because of the flexibility benefits this offers.
Solar Thermal Storage
Molten salt is the heat transfer fluid of choice. The salt used is a mixture of sodium nitrate and potassium nitrate. This material is plentiful and relatively inexpensive. In the dry state, the powder resembles the look of table salt. When heated to over 200 degrees C, it turns into a clear liquid. The liquid is stored in two tanks. The hot tank is 595 degrees C and the cold tank is 295 degrees C, to keep the salts in a liquid state. The size and insulating properties of the tanks, along with electrical loads, and the amount of sunshine directed at the plates determine the storage capabilities. This will be relatively short-term storage in the neighborhood of 6 to 24 hours. This storage capability is very advantageous to the operation of the electrical grid.
Advantages for the electrical grid
Peak demand for electricity is usually from 4 to 8 P.M. The sun is either not shining or at a poor angle for solar power production at these times. This is when the solar storage becomes very advantageous for the electrical grid. CSP with thermal storage can smooth out these demand peaks where other solar sources fail. The more wind and solar energy sources made available to the grid, the harder it becomes to balance. CSP with solar thermal storage helps to balance this profile and it becomes a symbiotic relationship with other renewable energy sources. Everyone wins!
Several projects are starting to come to fruition. In the U.S., major CSP projects are being built in the southwest as we speak. A CSP project in Spain recently announced they had supplied power for 24 hours. Their normal production time is 20 hours, but even this becomes a huge advantage over PV supplied electricity. Even though the energy storage is relatively short-term, this is a great benefit for CSP and PV. This will allow for more PV production during daylight hours while CSP is heating liquids for evening and nighttime use.
These are exciting times for solar and renewable energy proponents. Concentrating Solar Power with thermal storage is going to be a boon for all intermittent sources of renewable energy. The storage capabilities make this a game-changer. This really is a marriage of solar energy technology.