The original Stirling machine, developed 200 years ago by Reverend Robert Stirling, did not attain significant technical or commercial success until the latter half of the 20th century. An increased focus on this technology over the last 50 years has led to significant breakthroughs in terms of operating concepts and supporting technologies. 

The principal Stirling advantage: As a closed-cycle external combustion engine,
the heat source is outside the engine, so the inside of the engine can be maintained at high pressure. Stirling engines have a regenerative heat exchanger that allows them to re-use their heat to some extent. This feature is what makes the Stirling cycle so efficient. Since an external burner drives the Stirling engine, it can operate using virtually any heat source (e.g., oil, gas, solar, wood, coal, natural waste).

Until recently, the principal design used was the kinematic Stirling engine. There have been numerous attempts to integrate it as prime work engine in a variety of applications, but the high cost of manufacturing and reliability issues (inherent in its design) prevented it from achieving commercial success. However, newer variants of Stirling engines specifically the FPSEs (Free Piston Stirling Engines) ,have marked advantages.

The FPSE directly converts the reciprocating motion of the pistons into electrical power via a linear alternator inside the engine. Eliminating the crank mechanism and power output shaft in the kinematic Stirling engine solved fundamental issues of wear, sealing and reliability. The most noticeable FPSE advantages are high reliability, higher life expectancy, and zero maintenance.


Qnergy & Stirling

As a spin-off of Ricor, Qnergy was founded on the accumulated experience of more than 40 years of Stirling know-how. Based on an in-depth understanding of Stirling technology, and access to Ricor’s IP, Qnergy has taken a fresh approach in its development and manufacturing of engines and systems for residential, commercial, and industrial applications. This has helped in solving the energy production gap and benefits the environment.

Qnergy’s engines and systems' design provide an excellent solution to a number of power-generation applications, most important among them are: 

  • highly efficient generation of electrical power
  • high reliability and zero maintenance
  • very low noise and competitive price.