This photograph features the concentrating solar power (CSP) dish set a new world record for solar-to-grid conversion efficiency at 31.25 percent. The Stirling Energy Systems dish generates electricity by focusing the sun's rays onto a receiver, which transmits the heat energy to a Stirling engine. The engine is a sealed system filled with hydrogen. As the gas heats and cools, its pressure rises and falls. The change in pressure drives the pistons inside the engine, producing mechanical power, which in turn drives a generator and makes electricity.