4. Development and outlook

For many years, steam-driven power plants (SGPs) were the mainstay of power generation. These are still used worldwide, thanks to their much higher unit output than gas turbine (GT) power plants, as well as their greater efficiency. The main fuel used worldwide is coal, followed by fuel oil. Virtually all cycles are Hirn resuperheating cycles, with 6 to 8 extractions. Only a handful of power plants worldwide use a supercritical cycle (pressure in excess of 221 bar). Nuclear power plants, the majority in France, also use this type of thermal-mechanical energy conversion with a steam cycle at lower temperature and pressure.

One of the drawbacks of VMIs is the need to cool the condenser by circulating water. Steam-air exchangers have been considered, but never built because they are too large. This water circulation requires a sufficiently large river flow if air coolers...