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SunCatcher™ Technology |
How It Works
The solar dish Stirling technology is well beyond the research and development phase, with more than 20 years of recorded operating history. The equipment is well characterized with over 50,000 hours of on-sun time. Since 1984, the Solar Dish Stirling equipment has held the world’s efficiency record for converting solar energy into grid-quality electricity. This record was achieved when the technology was installed in Huntington Beach, California. SES coordinated with the U.S. Department of Energy and Sun-Labs (National Renewable Energy Laboratory and Sandia National Laboratories) to conduct an endurance test of the solar dish Stirling system and to bring the technology to market.
The SunCatcher™ is a 25-kilowatt-electrical (kWe) solar dish Stirling system designed to automatically track the sun and collect and focus solar energy onto a PCU, which generates electricity. The system consists of a solar concentrator in a dish structure that supports an array of curved glass mirror facets. These mirrors collect and concentrate solar energy onto the solar receiver of the Power Conversion Unit (PCU).
The PCU converts the focused solar thermal energy into grid-quality electricity. The conversion process in the PCU involves a closed-cycle, high-efficiency four-cylinder, reciprocating Solar Stirling Engine utilizing an internal working fluid that is recycled through the engine. The Solar Stirling Engine operates with heat input from the sun that is focused by the SunCatcher’s™ dish assembly mirrors onto the PCU’s solar receiver tubes which contain hydrogen gas. This heats and pressurizes the gas in the heat exchanger tubing, and this gas in turn powers the Solar Stirling Engine.
A generator is connected to the Solar Stirling Engine; this generator produces the grid-quality electrical output of the SunCatcher™. Waste heat from the engine is transferred to the ambient air via a radiator system. The gas is cooled by a water radiator system and is continually recycled within the engine during the power cycle. The conversion process does not consume water, as is required by most thermal-powered generating systems.
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New Power Conversion Unit (PCU)
The PCU is located in front of the centre of the dish, and possesses an external heat exchanger that absorbs the incoming solar thermal energy. The PCU measures the temperature variation among the dish’s quadrants and adjusts accordingly to equalize. The conversion process is performed utilizing a working fluid being efficiently recycled within a closed loop, consisting of four reciprocating pistons that powers the Stirling engine.
Concentrating
Solar-Thermal Power |
To Grid-Quality Electricity
The concentrated heat created causes the hydrogen fluid to expand and contract inside a closed loop system. It is this shift between intense heating, pressurizing and expanding of the internal hydrogen working fluid that drives reciprocating pistons. The change in temperature and pressure produces a mechanical power output, which in turn drives a generator. The result is the generation of electricity that is free of greenhouse emissions. Because the fuel is pure from the sun, there is no combustion, no exhaust valves, no carbon based emissions or pollutants. Moreover the Stirling engine operation is quiet.
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