Ripasso Energy concentrated solar power focuses the heat of the sun to highly efficient, zero-emissions Stirling engines. A test site in the Kalahari desert has reliably produced energy for four years and achieved a world record solar-to-grid electricity conversion of 32% and, big added bonus, uses no water, a major concern in deserts. By contrast, traditional solar PV has achieved about 15% usable grid power, while other forms of concentrated solar use water to power steam turbines.
The technology works by using the mirrors as giant lenses that focus the sun’s energy to a tiny hot point, which in turn drives a zero-emission Stirling engine.
The Stirling engine was developed by Reverend Robert Stirling in Edinburgh in 1816 as an alternative to the steam engine. It uses alternate heating and cooling of an enclosed gas to drive pistons, which turn a flywheel.
Ripasso says competing with the ever-dropping costs of solar PV is crucial. Their biggest challenge was getting funding from skeptical banks, so they secured private funding instead. Solar power like this would be an ideal way to power desalination plants on the coasts in deserts, as well as homes.