What is a Solar Power Tower?
The Solar Power Tower is a large-scale solar thermal power system that uses mirrors to direct and concentrate sunlight into the tower-designed structure.
Its early form uses a water-filled boiler to generate steam on top of it. The steam then flows into a turbine (a giant fan) connected to an electrical generator. As the turbine spins, electricity is produced.
Today's designs utilize molten salt to store thermal energy at extremely high temperatures and release it later to produce steam.
The Solar Power Tower system is unlike photovoltaic cells (solar panels), which only capture light from the front of the cell and require a significant amount of area for a large-scale power plant.
It can be built to run on molten salt, which does not freeze at night or in colder weather, to increase efficiency and permit a higher solar radiation concentration to reach the receiver.
This makes it possible for a Solar Power Tower to produce electricity 24 hours a day, year-round, even in places where there is limited direct sunshine.
How It Operates
A Solar Power Tower consists of a large circular parabolic trough with a receiver at the focal point.
The mirrors focus the Sun's energy onto this receiver, heating heat-transfer fluid (molten salt) and generating high-temperature heat. The hot molten salt produces steam that immediately turns a turbine and produces electricity, just like how conventional power plants generate electricity.
The system requires no solid fuel, emits no air pollution, and uses virtually no water in its operations.
Solar Power Technology Pioneers
There are two pioneers in the use of solar power technology. These are Solar One and Solar Two.
Solar One
The first commercial solar power tower, which ran from 1982 to 1988, was Solar One. It was built in the Mojave Desert. Although it could store energy used for start-up in the morning, it was not efficient enough.
The system also stopped working when there were passing clouds or the fall of night.
Solar Two
Because of Solar One’s lack of efficiency, it was redesigned and modified to become Solar Two, completed in 1995. Solar One used oil as a heat-transfer material, but the redesigned Solar Two system used molten nitrate salt, which is more efficient in storing thermal energy and is non-toxic and non-flammable.
It was composed of 2,000 heliostats and a better storage system. Additionally, it had a tracking system so that the heliostats could follow the Sun with their mirrors.
The University of California, Davis utilized the Solar Two as a telescope to measure gamma rays hitting the atmosphere after its decommissioning. Solar One and Solar Two's central were torn down in 2009.
Environmental Concerns
The Solar Power Tower system is free of greenhouse gas emissions, air pollution, and noise.
Although the Solar Power Tower itself creates no waste, its production can emit certain gasses such as carbon dioxide (CO2), contributing to global warming. Its construction may also require energy for materials processing, fabrication, transportation, and installation.
Second, the demand for water for these solar towers may be seen as an issue because a large volume of water is required to operate. To address this concern, research on alternative cooling technologies is being explored.
Finally, the use of these towers has harmful effects on birds. Birds that fly in the way of the focused rays of the Sun can be incinerated. Some reports claim that one bird dies every two minutes at power plants.
Advantages and Disadvantages of Solar Power Tower
Solar power towers pose both advantages and disadvantages.
Advantages
- Although Solar Power Towers rely on the Sun and its ability to power up towers depends on daylight, these plants can continue producing energy even when the Sun goes down.
- They produce electricity 24-hours a day, unlike conventional energy sources such as coal and oil, which are limited by supply and production costs.
- It does not require any fuel, only abundant and free sunlight.
- Solar Power Towers do not produce any harmful emissions or waste.
Disadvantages
- The Solar Power Tower system is currently the most expensive form of solar power.
- Its construction requires a vast area of land.
- Compared to Stirling systems, its efficiency is lesser.
- As the number of large mirrors increases, more support is needed for a rigid structure.
- The efficiency of the solar power tower system can be affected by the wind causing problems with the mirrors.
Final Thoughts
Although Solar Power Towers are only beginning to be popularized, it is a promising technology that can help solve problems with conventional power sources and harness the Sun's energy.
It can provide clean and reliable energy for homes without any harmful emissions or waste. However, its high price would have to be addressed before it becomes available in the market for general use.
FAQs
1. What is a Solar Power Tower?
A Solar Power Tower is a solar thermal power plant that uses an array of flat, movable mirrors to focus sunlight onto a tower covered with water pipes. The heated water flows from the tower to a conventional steam-generating boiler. The steam produced drives a turbine and creates electricity.
2. How does a Solar Tower operate?
Solar Towers operate using a large array of computer-controlled mirrors (called heliostats) to focus the Sun's rays onto a tower. The tower summit is enclosed with water pipes and inside these pipes flows superheated steam, which drives turbines and produces electricity.
3. What is Solar One?
Solar One was a Solar Power Tower in Barstow, California. It was the first to be built on a power plant site.
4. What is Solar Two?
Solar Two was a Solar Power Tower located at the same facility as Solar One. However, it had an advanced design to produce more power.
5. What are the environmental concerns with Solar Power Towers?
Solar Power Towers have been accused of being environmentally unfriendly because they use large amounts of water for cooling which means that it has a high electricity demand. In addition, Solar Power Towers can pose a threat to birds that fly in their way as they can be incinerated.
