Contributor: Daryl Bessa, President of F.E. Moran Special Hazard Systems
Writer: Sarah Block, Marketing Director of The Moran Group
The sun beams enough energy in one hour to power the entire world for one year. However, the world is still in the beginning stages of adopting this renewable energy source. There are many aspects of solar power that are misunderstood. A major misconception is the idea that solar power plants have no inherent fire risk. The majority of large scale solar power plants are concentrated solar power plants (CSP), which use solar energy to power conventional steam turbines. Therefore, CSP plants have the same fire hazards as many conventional power plants. With the push to "green" energy, CSP plants are gaining popularity. Currently, 1,000MW of energy from concentrated solar power is under construction (cleantechnica.com); enough to power 200,000 homes. With the rapid growth of this form of energy, how do we keep it protected from fire?
Converting the Sun into Power
Harnessing the sun's energy into usable electricity is one of the cleanest forms of power. It is a renewable source of energy that will faithfully rise each morning. The process of converting the sun's rays into power is relatively simple, but can create fire hazards that must be protected.
CSP plants use a series of lenses, mirrors, or heliostats and tracking systems to condense sunlight into a narrow beam of light. Solar plants have numerous options for technology that condenses the sunlight into a beam: Concentrating Linear Fresnel Reflector, Stirling Dish, Linear Parabolic Reflector/Parabolic Troughs, Solar Dish, or Solar Power Tunnel. The intense beam of light created is then used to provide heat to power a conventional steam turbine.
The concentrated beam of sunlight is used as a heat source to warm the heat transfer fluid, molten salt, or steam generator to power the steam turbine. The steam turbine is connected to a generator, which produces the energy.
Because concentrated solar power plants are a combination of solar energy and steam energy, the same fire hazards are present as in many other power plants.
Hidden Fire Hazards in a Solar Power Plant
Solar power: the words themselves give the illusion of safe energy. However, CSP plants share several of the fire hazards that many standard plants possess. Lube oil systems, transformers, turbine bearings, switchgears, and other areas of concern associated with conventional plants should be considered.
In an HTF type plant, the solar field has its own fire hazards. The concentrated sunlight created from the solar field is used to bring the heat transfer fluid to a high temperature. The heat transfer fluid flows from the solar field to a standard steam turbine. The heat transfer fluid is generally a form of oil and can be very flammable. The heat transfer fluid introduces a fire hazard to the solar field. The heat transfer fluid pump and pipe racks can be protected with deluge systems and linear heat detection.
The heat transfer fluid flows until it reaches the heat exchanger which can be another potential problem area. The steam turbine uses lube oil to keep it moving smoothly. Fires can ignite within the turbine underfloor, exciter, lube oil piping, or the turbine bearings. It is recommended that a robust fire protection system is installed in this area. An automatic sprinkler, foam-water sprinkler, or deluge system is appropriate for the turbine area. An early warning detection system will ensure that the plant personnel are given adequate notice of a fire ignition. A fire protection solution provider will be able to provide custom recommendations based on the plant's particular hazards.
The next step in solar energy generation is the generator, which produces the energy. The generator contains lube oil, and/or hydrogen which can fuel a fire from the slightest spark. To protect a generator, a pre-action sprinkler system or inert gas system is ideal. They reduce the likelihood of an accidental discharge while protecting delicate equipment.
Cooling towers are often thought of as fire resistant because they are usually wet; however, cooling towers contain hidden dry areas and are completely dry during maintenance. Cooling towers are made from combustible materials. The heat source in a cooling tower fire can come from outside sources, such as a fire from another part of the plant that has spread or internal sources, such as maintenance welding, overheated bearings, or electrical failures. A concern within cooling towers is the accelerated corrosion of piping, including fire protection pipes. Plants must take this into consideration and adjust the inspection, testing, and maintenance schedule for this part of the plant.
Concentrated solar power plants provide a clean, renewable form of energy throughout the world. However, inherent fire hazards may be overlooked within this form of energy generation. Plants must protect the valuable assets, people, and production with a proper fire protection solution. Work with an experienced fire protection solution provider to ensure all fire hazards are adequately protected with robust fire sprinklers and detection systems.