100 % carbon-neutral electricity from industrial residual gases and waste heat

A technology with a history…

The Stirling engine, which is what is referred to as a gas pressure engine, was invented in the early 19th century. From an historical perspective, its practical applications has been limited, compared to the internal combustion engine, with the result that the technology has never had a major commercial breakthrough. Combined with an overall societal push to reduce the use of fossil fuels, the refinements made to the technology in recent decades may mean that the breakthrough is imminent.


…and unique characteristics

The Stirling engine has a number of characteristics making it particularly well suited to the development of climate friendly, cost effective power generation solutions. Among other things, the Stirling engine can in principle be operated using any heat source. The combustion that drives the engine takes place externally – i.e. outside of the engine itself. It is quiet and virtually vibration-free. Above all, the Stirling engine features very high efficiency in its ability to convert thermal energy to kinetic energy.


The engine's simple operating principles

In its simplest version, the Stirling engine is a closed system with an expansion cylinder and a compression cylinder filled with a working gas. The pistons of the cylinders are linked by a connecting rod. When the working gas in the expansion cylinder is heated, pressure increases. This depresses the piston and thus performs work. Part of the force is used to push the hot working gas from the expansion cylinder into the compression cylinder. Once its outward motion in the compression cylinder is arrested, the piston returns by the inertia of the connecting rod, and by the fact that the working gas is compressed at low temperatures. The gas is then forced back into the expansion cylinder. Overall, the expansion of the hot gas in the expansion cylinder does more work than is needed to compress the cold gas in the compression cylinder. This work can be used to drive an electrical alternator that is directly connected to the engine’s connecting rod.