Test Results From a Concentrated Solar Microturbine Brayton Cycle Integration

Abstract

Capstone Microturbine and Heliofocus Solar Thermal Solutions in a partnership built an open loop Brayton cycle system using a 65 kW Capstone Microturbine and a concentrated solar energy receiver. This system was built for initial development testing to validate the ability to generate electricity on a small scale at high efficiencies using only solar energy as the input. A secondary goal was to demonstrate the ability of the receiver to transfer sun energy into the working fluid of air at efficiencies that would support the target overall system electrical efficiency of 21%. Concentrating Solar Power systems in the 20 kW to 100 kW electrical output power range currently do not exist in the market place today. Demand for this type of power generation is high due to its small footprint per kW of energy produced, its ability to be distributed in small kW increments to meet site demand and space, its relatively high electrical efficiency and its projected low cost per kilowatt of generated electricity. This initial testing was done without the production configuration dish concentrator component and instead a solar tower with a field of Heliostats provided the sunlight to the solar generation system. Test results showed that the receiver met the efficiency goal set forth and that the overall system was capable of producing 25kW of electricity to the electric grid. The receiver efficiency measured was 89% at or near the needed airflow and air temperature levels required by the Microturbine to support an overall system efficiency of 21%. The next step in the development process would be to integrate the development system onto a concentrating solar dish and demonstrate the total conversion efficiency at the target 21% prior to commercialization.