I did some research and found out that in order to generate that amount of electricity( consider about 100MW) the size of the Stirling engine will be very big as compared to that of a steam turbine.

But then some articles said that upon using helium in the Stirling engine the size will become much smaller. This will also increase the power density of the engine.

If this is the case then why is Stirling engine not used, is this due to lack of research since steam turbines became popular.

  • $\begingroup$ Could you update the question to include the references/url links to the articles you are referring to? $\endgroup$
    – NMech
    Commented Jan 26, 2021 at 6:42
  • $\begingroup$ "Steam Turbines for Modern Fossil-Fuel Power Plants" by Alexander S. Leyzerovich. This book chapter provides an in-depth discussion on the design and operation of steam turbines, as well as their advantages for large-scale power generation. $\endgroup$
    – user13416
    Commented Mar 17, 2023 at 2:35

2 Answers 2


Several reasons

  • poor thermodynamic efficiency. It's fairly low. Where as the modern gas turbine has an efficiency of 44-66% and with waste heat capture 80+ percent.
  • stirlings use conduction to transfer heat...this leaves huge energy losses. And makes them less efficient in warmer climates.
  • low power to weight ratio..which is why despite simplicity steam engines replaced them in ships.

On the other hand low temperature stirlings might be able to capture waste hear for accessory uses...

  • $\begingroup$ Your second point isn't really accurate. Turbines are also less efficient in warm climates because the cold temperature in the thermodynamic cycle is higher. That's why power plants use cooling towers to lower their cold temperature below ambient. $\endgroup$
    – Emily Conn
    Commented Jun 21, 2022 at 12:56

My guess, is that even with helium the power density of the Stirling engine would not be that great compared to the steam engine, helium is quite expensive to be used in large volume application and also has a tendency to leak.

From the Power to weight ratio widipedia page, the power to weight ratio for a Stirling engine made by NASA and DOE in 1985 is 0.30 [kW/kg].

For comparison, the 1930's Junkers Jumo 205A two-stroke, diesel, opposed-piston engine had almost double weight to ratio (1.1 kW/kg).

  • $\begingroup$ The other thing to add is resource availability: the suppliers of helium are very few in number, whereas water for steam generation is more easily acquired. $\endgroup$
    – Fred
    Commented Jun 20, 2022 at 9:26

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