Main Advantages
Simple and cost effective structure
The external frame is manufactures using pre-cast pre-stressed reinforced concrete. This proven technology is well known in the construction industry. Pre-fabricated structures are appreciated not only for their decreased initial cost as well as their long life span andstability against atmospheric agents. They therefore require less maintenance. The relatively heavy concrete structure also offers a good rigidity against wind loads as well as overall stability.
Very rigid structure
In the field of pneumatic structures, research and studies have shown that a properly designed “pneumatic pillow” demonstrates great rigidity even at very low internal pressure, in the order of 2-4 mbar. This characteristic, combined with the well known properties of concrete beams, allows the creation of larger solar collectors, with better structural behavior, increasing therefore the overall thermal efficiency.
Rapid ‘on site’ structure construction
A 50 MW power plant, built with traditional techniques & systems, requires approximately 20’000 tons of steel. Such steel elements must be transported and assembled on site, generally rather distant from manufacturing sites. Moreover, steel prices are increasing because of its limited availability. These are limiting factors for construction speed and correct cost forecasts. Our structural system may rely on local construction companies, local raw materials and resources, avoiding high transportation costs and minimizing manufacturing time. In a sustainable development realm, concrete is a construction material possessing less “gray energy”, therefore more environmentally-friendly.
Very simple, lightweight and efficient mirrors
In traditional concentrators the reflecting surface is made of glass parabolic mirrors of 150 x 150 cm and 4-5 mm in thickness. Suchmirrors must be mounted on the steel frames using mm precision, and each minimal inaccuracy must be compensated for or the focus line will be incorrect therefore reducing thermal efficiency.. Furthermore, breakages due to wind or thermal shrinkage, are quite frequent.
Very simple, lightweight and efficient mirrors
The ALE approach is completely different: the perfect cylindrical shape is provided by air pressure. Such overpressure may constantly and automatically be adjusted in a precise way. The Mylar mirror is fixed to the structure mechanically only along the edges. The foil is delivered in rolls, so a coil of 2 m in diameter can easily contain 80’000 m2 of mirror. The reflecting power of such Mylar mirror is considerably high, if compared to conventional glass mirrors. Mylar has already demonstrated its reliability in aerospace applications.
Fast delivery time
Contrary to glass mirror, which requires extensive manufacturing time, the membrane used in our project are produced in large quantities (several millions of m2 ) on a yearly basis using very high quality standards. Therefore, production capacity and costs will not be a problem. On the contrary, parabolic glass mirrors have already reached its production limits as they may be applied only in solar collectors and therefore need to be manufactured specifically for this purpose.
Low maintenance costs
Unlike steel, concrete structures do not require special maintenance such as paint or anticorrosion coating.
Their mirror surface, is especially prone to dirt and abrasion. In our case, this is inside the pillow where the air is filtered and dried. The delicate reflecting surface is never in contact with atmospheric agents. The external ETFE film, well known for its excellent self cleaning properties (Teflon) is more and more frequently applied for greenhouses rather than glass. On the other hand, the glass mirror should be cleaned on a weekly basis using water, which is generally very precious in arid regions, and abrasion will shorten its life.
Air & Storage
Air as thermal fluid enables the use of a packed bed storage system, allowing the system to cut the power block costs and use the turbine (steam or air) in a more efficient way through its continuous operation. The main advantage of air is its zero cost: water may be an issue in desert areas, thermal oil is still toxic and expensive and molten salt creates several technological problems which have not been solved yet. Using the storage it is possible to enter the regulation market, where electric power may be sold at much higher prices, increasing the overall benefits of the system.