That's all that our refrigerant engine needs in order to make power. The exhaust vapor is recycled in our patented closed-circuit piping system. Sterling's thermal power plant is unique in that its recycling pump consumes heat, not power. There is nothing natural about freon. Refrigeration was discovered in an early experiment with ammonia.
Ammonia is used in many modern refrigeration systems.
Sterling's power plant can use any refrigerant. The refrigerant working fluid can be heated by almost any heat source. Solar, geothermal, waste heat, wood, propane. High temperatures aren't necessary. A garden hose reaches the required temperature.