Next generation concentrating solar power (CSP) system designs use supercritical carbon dioxide (sCO2) turbine power cycles to more efficiently convert solar thermal energy to electricity and to reduce the cost of CSP technology. Because sCO2 power cycles work best at very high temperatures and under intense pressure, a CSP system needs receivers and heat exchangers that can withstand these conditions. Heat exchangers can amount to 60%-70% of the total cost of a CSP sCO2 turbine system, so low-cost, highly efficient exchangers are needed to help make CSP cost-competitive.
Enter Brayton Energy. Thanks to funding from the SunShot Initiative, Brayton was able to develop the first sCO2 solar receiver designed for commercial use. The receiver will enable the operation of a sCO2 power cycle by directly heating the turbine working fluid inside the receiver. The company’s innovations are twofold. First, the new solar receiver panel design captures concentrated sunlight more efficiently than traditional tube-type receivers. Second, an internal webbing architecture was added that enables a thin wall receiver surface and creates greater internal surface area. This increases heat transfer through the solar absorbing surface and enhances heat transfer to the flow of sCO2 at high temperatures and pressures.
Under its CSP SunShot Research and Development award, Brayton was able to develop, test, and demonstrate the effectiveness and durability of its new solar receiver. Brayton’s receiver uses low-cost materials, while the new design far exceeds the performance of current state-of-the-art receiver. Brayton’s innovations can reduce the cost of a heat exchanger by 40%, significantly curbing capital costs for constructing a CSP plant and making the technology more attractive to investors. Brayton’s new technology is already moving outside of the lab and has been incorporated into a number of commercial heat exchangers for industrial clients.
Leveraging the advances developed during this project, Brayton Energy partnered with Savannah River National Laboratory (SRNL) to develop an integrated receiver/tower/engine/thermal energy storage CSP system that is cost-competitive with fossil fuel electrical generation, addresses the real-time needs of the electrical grid, and produces zero greenhouse gases. The new project couples Brayton’s sCO2 receiver technology with SRNL’s metal hydride thermal energy storage system to create a modular, low-cost system. The partners were recently chosen to develop this project under a SunShot Concentrating Solar Power: Advanced Projects Offering Low LCOE Opportunities (CSP: APOLLO) award and will pursue the project through 2017.