This pneumatic rotary piston engine provides trouble-free use for an uninterrupted power supply. It is characterized by high performance and extremely fast response times. It comes in 50 to 500 kW sizes and requires less than 30 milliseconds to start, going from 0% to 100% load. For energy storage it uses compressed air, which is available in virtually unlimited quantities. Pivoting valves for air intake are mounted on the rotor of the motor. The bearings must be statically very stress- and temperature-resistant, with low static friction and high resistance to dirt. Initial trials with Carobronze bushings failed, because after a short period of use the bearings got clogged with dust particles and the valves would no longer open. Ball bearings and needle bearings were also unsuitable, because they required lubrication. Only the lubricant- and maintenance-free iglidur® plain bearings made for lasting, friction-free valve operation.