SHEC has developed a suite of Concentrating Solar Power (CSP) technologies as follows:
SHEC Energy has developed the world's most efficient Solar Thermal Power (STP) technology. Our patented technology resolves the primary energy loss issues experienced in other systems. At higher operating temperatures in the range of 800°C to 900°C, emissivity (radiant energy) losses become extremely high, increasing by temperature to the 4th power. This results in a very large percentage of energy loss in competitive high temperature systems. SHEC Energy has an emissivity loss of only 2% at 850°C. These higher operating temperatures significantly increase thermal to mechanical energy efficiencies in both steam turbines, sterling engines and other forms of heat engines. These higher temperatures also lend themselves well to much higher temperature storage solutions compared to those in existence today, such as molten salt.
The technology works on the principle of super concentration, reducing the target size significantly compared to other technologies. Super concentration creates new problems due to solar beam density being so high as to be destructive to the solar receiver. SHEC Energy invented new technology that is able to harness this intense beam without target destruction by using a substantially reflective optical cavity receiver. The solar beam entering the cavity is partially absorbed upon the first bounce with the majority of the beam reflecting elsewhere in the cavity and a small percentage is again absorbed and so on as the beam propagates through the cavity. This results in a non-destructive absorption of the solar beam over a large internal area with a small entry aperture.
Super concentration requires the use of rigid structural mirrors. Glass is the only viable option to achieve this. Glass also provides for a robust mirror as well. The processing of glass mirrors, however, has been slow and costly. SHEC Energy has invented proprietary technology to form glass mirrors that is 30 times faster than compared to traditional processes. SHEC Energy has been awarded a grant of about $40 million to establish optics manufacturing using this technology. Since mirror structures is one of the most costly aspects for solar energy collection in CSP systems, SHEC Energy has a significant advantage with this technology.
In CSP thermal based systems, it is necessary to transport the heat from the solar concentrators to the power block where the thermal energy is converted to mechanical and then electrical energy. Traditional heat transfer fluids have consisted of oils or molten salts limited in temperature to 400°C and 560°C respectively. Since SHEC Energy's solar collection systems can operate in excess of 900°C, we have developed technology to allow us to transfer heat at these temperatures. This is key to higher efficiency power generation and key to high temperature thermal storage in order to maintain overall higher efficiencies in a stored energy system.
The primary means of storing thermal energy today is with molten salt. Due to the driving force or temperature differential (delta-T) required for effective heat transfer to a steam turbine boiler, the steam temperature is a couple of hundred degrees cooler than the storage temperature. For example, a molten salt system operating at 560°C may only be able to deliver 280°C steam to a turbine. This relatively low temperature results in relatively low operating efficiency. SHEC Energy's Storage technology on the other hand, could deliver steam temperatures of 570°C, significantly improving turbine efficiencies. This also has the potential to extend the off-sun operating time, so that base load power could be primarily generated from solar.
SHEC's technology can be directly applied to steam generation without modification. SHEC is currently working with companies for industrial steam applications.