247Solar, an MIT-spinoff, and microturbine maker Capstone Turbine tested a commercial turbine that can generate electricity using hot air at atmospheric pressure, without combustion. This is made possible by a heat exchanger using a nickel-chromium-aluminum-iron alloy engineered for operation at very high temperatures. The plant is driven by a CSP system that heats air to a high-enough temperature to drive the turbine to produce electricity. According to the company, the hot-air-driven Brayton Cycle system “operates at atmospheric pressure and requires no steam, molten salts, or heat transfer oils.” The system stores up to 20 hours of energy as heat, using ceramic pellets instead of molten salts.  Source: 247Solar