CST systems use long parabolic mirrors to focus sunlight on a vacuum pipe that runs through the trough of each mirror. The mirrors and pipe move throughout the day to maintain the focus on the pipe. The pipe contains a heat transfer fluid (traditionally an oil derivative) that carries the collected heat energy to a heat exchange system, effectively converting water into steam. The steam drives steam turbines and produce electricity. One major advantages of CST lies in its applicability to current turbine systems present in most power plants. “Recycling” turbines in this manner enables conversions from fossil fuel to CST plants at very low cost, making CST easily scalable if energy demand increases. CST can also easily and cheaply store energy in the heat transfer fluid with almost 100% efficiency. A CST power plant can thus draw on the heat in the fluid (stored during the day) at night to continuously produce electricity. Solar panels only produce electricity during the day and wind power is naturally intermittent, hence disqualifying both from becoming major supports of a power grid. Furthermore, CST has proven its reliability: CST has been used in the United States since the parabolic collectors at the SEGS plants in California for nearly 20 years. Among the options for alternative energy production, CST plants may prove to be the primary means of producing the constant power supply necessary to become a substantial part of electricity production.
Because of these advantages, CST is projected to grow massively, with research reports predicting that 12 GW of CST capacity will be installed by 2020, almost all of it in large plants over 100MW. Recently, political concerns about high natural gas prices, pollution from coal plants and climate change have led to many states passing renewable energy mandates. This assures demand for new CST plants as utilities search to meet environmental policies like the California Renewable Portfolio Standard, which mandates that 20% of the state’s electricity must come from renewable sources by 2010. However, the problem with CST systems lies with its cost, not its efficiency. Fields of huge, precisely shaped, breakable glass mirrors are extremely expensive to build and maintain. And even a cutting-edge CST plant must charge more than 13 cents per kWh, a standard price for wind power.
SkyFuel is positioned to capitalize on CST growth because it presents an ingenious solution to the cost problem. SkyFuel’s system, SkyTrough™, uses its patented Reflectech™ mirror film in the parabolic reflector troughs instead of traditional glass mirrors. Reflectech™ mirror films are similar to plastic, consisting of many polymer layers over an inner layer of pure silver that gives it reflectance equal to a parabolic mirror. Furthermore, Reflectech™ is shatterproof and significantly lighter than heavy glass mirrors. Reflectech™ is so light that it can be laminated to aluminum sheets to create larger panels than the largest feasible glass mirrors, increasing accuracy of light concentration (and thus efficiency), while decreasing assembly costs. Since the support apparatus of SkyTrough™ can maintain lower weight than glass mirrors, engineers could use a tubular aluminum space frame that is 30% lighter. The space frame not only lowers weight strains, but also allows easier installation, hence reducing labor costs.
These benefits aggregate to make SkyTrough 35% cheaper to build and significantly cheaper to operate than any CST system on the market today. Additionally, Reflectech™ films eliminate the bottleneck in the parabolic trough production process (making the sagged glass mirrors) allowing SkyFuel to rapidly produce SkyTroughs™ and reducing lead time for orders. Armed with this innovative solution to its cost problems, CST power is positioned to supplement the conventional means of electricity production in the United States.