Energy becomes scarce and expensive. There are also good reasons to counteract the looming global warming. One possibility provides the utilization of the energy emitted into the environment from heat and gas expansion processes. In many cases, this energy can be converted into electrical energy afterwards (e.g. by ORC). For this purpose high-speed turbines with a downstream electrical generator are mostly used. The feed-in system SD2R from Sieb & Meyer is developed according to the applicable standard (VDE AR 4105) with highest efficiency and powers between 12 KW and 80 kW. Generator speeds up to 120,000 rpm are controlled sensorless, also motordriven. Flywheel is another interesting field of application for the system. These store excess energy by use of high-speed motors that can be supplied on demand. In addition, there are various opportunities for the connection to a higher-ranking control.