FAQ
What happens if there is a hole in the membrane and the air escapes?
The inner overpressure is constantly maintained by blowers, so a hole would not have an impact on the inner pressure. In reality, there is always some air loss as it is almost impossible to build a large inflated structure which is completely airtight. Moreover, the fluctuations in atmospheric barometric pressure resulting from changes in weather are greater than the inner pressure, so automated regulation and compensation is required to maintain the required internal pressure.
How large is the inner pressure? Is it dangerous?
The inner pressure is a few mBar, enough to compensate for wind loads. In comparison, a person can inflate a balloon with 150-200 millibar pressure, and the tires of a car are inflated with 2'500 millibar. So when there is air loss due to a puncture, the air escapes very slowly and it would take up to 1 hour to deflate the structure completely without the activation of external blowers. Thus, maintaining the pressure inside of the pillow housing is straightforward.
What is the life span of the plastic membranes?
Plastic is a generic term that encompasses hundreds of polymers and byproducts. The film used by Airlight Energy in its collector is comprised of two types of plastic: ETFE (Ethylene tetrafluoroethylene), and Mylar. Both are very high quality polymers. ETFE is a Teflon-based polymer which is currently used as a replacement for glass in greenhouses. It has excellent self-cleaning properties and is scratch resistant. It is transparent to UV radiation with no known degradation from to exposure to the sun. Many large and modern structures are built with ETFE material.
Bubbles Building Olympic Stadium.
What happens in the event of fire?
ETFE does not burn as it is fire retardant. For this reason, it is currently being used in civil engineering. If exposed to high temperatures (> 260°C), it will simply melt. The same is also true for Mylar, although not as fire retardant as ETFE, it has similar beneficial properties.
Can such plastic foils resist desert temperatures?
Yes, ETFE can operate at temperatures reaching 160°C and Mylar 150°C, which is well above environmental conditions within the collector, which may at times reach a maximum temperature of 80°C.
How long does it take to build a 50MW power plant?
A 50MW power plant would have a solar field of approximately 750 acres with 480 banks of solar collectors containing collectively over approximately 200'000m3 of concrete for 24 hour storage version, and 250 acres with 160 banks of solar collectors containing over approximately 33'000m3 of concrete for only 8 hours of production with no storage. A significant advantage of Airlight Energy's concrete frame is the fact that the construction industry has a great deal of experience in working with concrete structures. The amount of concrete called for in one of ALE's bank of collectors (250m long by 12m wide, which is approximately 400m3) is actually not much compared to a bridge or even a large building such as a hospital. Accordingly, construction schedules for the solar field can be compacted, with the expectation that 1 to 1.5 years would be sufficient in any part of the world (separate from the delivery of the power block which may take more time). Another advantage of Airlight Energy's collector is that there is no bottleneck in the delivery of mirrors due to the fact that the production of Mylar film is so extensive worldwide that in 3 hours a medium-sized company could produce the entire film required for a power plant.
What happens is there if a failure in a solar collector system?
A CSP power plant is divided into several main components, including the solar field. If there is a failure in one of the solar collector systems within the solar field, then the single row containing the failed system can be shutdown for repairs, with the overall solar field power output being reduced only by a small percentage. The electric output can be kept constant by temporarily extracting more energy from the storage, until the failed system is repaired and the row brought back on line.
Why do you say that it is easier to build a storage system if you use air?
The packed gravel bed storage system is an existing, proven concept, which has been used mainly in the chemical industry and has also been proven by means of several theoretical and practical analyses. In principle, the packed gravel bed exploits the low thermal conductivity properties of stone and air to keep a internal thermal gradient between the higher temperature upper portion of the tank and the colder lower part. While "loading", the slow hot air flows through and in contact with the large volumetric surface of the exterior of the gravel, ensuring that the thermal energy contained with the heated air is completely transferred to the gravel. This heat transfer process is reversible by blowing cold air from the bottom of the tank up through the gravel to extract the heat that has been stored inside of the gravel. Consequently, the temperature at the top of the tank where the outlet is located remains constant until the tank is almost "empty".