Electricity generation is essential for the development of society, but it also implies a great environmental challenge, due to the intensive use of water and the emission of greenhouse gases.

To meet this challenge, innovative solutions are needed to increase the performance and efficiency of thermal power plants while minimizing their environmental impact.

One of these solutions is the hygroscopic cycle, a technology created by Francisco Javier Rubio Serrano, who is currently the director of engineering at IMASA Energía, and developed by the company IMASA, INGENIERÍA y PROYECTOS, S.A.

This thermodynamic cycle represents an evolution with respect to the Rankine cycle, since it allows working with hygroscopic compounds to improve steam condensation at the turbine outlet. By absorbing water vapor, these compounds raise the condensing temperature to a constant pressure, which improves process efficiency by significantly reducing subcooling. The use of a vapor absorber and dry air coolants avoids the need for cooling water and reduces electricity consumption.

The hygroscopic cycle uses the same chemical additives as a conventional steam cycle, such as pH stabilizers, corrosion inhibitors and oxygen scavengers, which already have hygroscopic properties, so there is no need to change the existing additives.

Hygroscopic Cycle and Rankine Cycle: are they the same?

The hygroscopic cycle shares several similarities with the Rankine cycle, but stands out, above all, for its ability to implement improvements similar to those of the conventional cycle. This makes it possible to achieve even higher performance compared to the Rankine cycle, thanks to improved cooling conditions, influenced by the use of various hygroscopic compounds.

Advantages of the Hygroscopic Cycle

This cycle presents a series of significant advantages, both from an environmental and operational point of view, among which the following stand out:

  • It eliminates the use of cooling water, which saves resources and reduces pollution. It also avoids the problems associated with cooling towers, such as spills and chemicals.
  • Greater freedom of location, as it does not require cooling water consumption, it allows greater freedom when locating the plant.
  • It allows working with very low condensing pressures, which improves the net electrical efficiency in a Rankine cycle. Thus, maximum use is made of the energy of the steam leaving the turbine.
  • It reduces operating and maintenance costs by simplifying plant design and using hygroscopic compounds that protect the cycle from corrosion, pH and fouling.
  • It offers maximum operational flexibility, as it adapts to environmental conditions and plant needs. It also allows the incorporation of improvements to the Rankine cycle, such as superheating, superheating, regeneration or supercritical conditions.
  • Reduces noise impact compared to current technologies
  • It enables dry cooling in environments with temperatures above 40ºC, which is a breakthrough for power generation in arid or water-scarce areas.

It also eliminates visual impacts, such as plumes, and aligns with COP21 and COP23 objectives to mitigate climate change.

Hygroscopic Cycle Applications

The Hygroscopic Cycle stands out for its versatility, offering key applications in the field of power generation and industrial process optimization.

Areas where this cycle finds its maximum impact include:

  • Power Generation:
  • Thermoelectric Power Plants.
  • Solar thermal.
  • Biomass Plants.
  • Nuclear Power Plants.
  • Combined Cycles.
  • Geothermal energy.
  • Cogenerations.
  • Process Vapor Condensation.

And it can be implemented in both new construction facilities and existing plants, offering a substantial improvement in competitiveness by reducing production costs in each of these areas.


The implementation of the Hygroscopic Cycle saves cooling water, increases performance, reduces maintenance costs and eliminates smoke plumes. This opens up new possibilities for previously unfeasible projects, thanks to technical, economic and environmental improvements, facilitating their success and contributing to the expansion of energy generation in a more efficient and sustainable manner.