English EN Română RO Italiano IT Deutsch DE

Heat Recovery from Engines

Diesel engines typically convert no more than 33% of the energy contained in their fuel in mechanical energy; about 25% of the energy input ends up in the cooling circuit and 33% in the exhaust gases (source: SAE ). So, it is evident how any intervention having the purpose of recovering at least a part of that large waste of energy is welcome.

Zuccato Energia ORC modules – thanks to their low operating temperatures – represent an excellent choice to recover waste heat from a wide range of engines and gensets, to which they may be interfaced safely and easily through a simple hot- or overheated-water loop that insures efficiency, safety and simple engineering.

Heat wasted by an internal combustion engine can be recovered in different places:

  • Exhaust gases, by inserting a fume/water heat exchanger in the exhaust piping;
  • Engine cooling jackets, by inserting a water/water exchanger in the cooling water circuit;
  • Oil cooling circuit, particularly in larger-size engines (e.g. naval applications).


Heat recovery from oil and cooling jackets is made possible by the exclusive low-boiling working fluid used in the Zuccato Energia ORC modules. The system sizes of the Zuccato Energia ORC systems lend themselves perfectly to recovery from these sources, simplifying the possibility of retrofitting to existing systems, considering that where the heat coming from only one of these sources is insufficient, it is possible to collect it from more sources (e.g. fumes + shirts).

Zuccato Energia has already installed several plants of this type , recovering heat from MAN, Jenbacher and Caterpillar gensets fueled by biogas, syngas and vegetable oil (see references in sidebar), and has also developed a product line specifically designed for heat recovery from naval engines, where retrofitting ORC modules in place of existing gensets allows a significant fuel saving.


Zuccato Energia has a long experience in recovering engine heat, with several installations on MAN and Jenbacher engines as well as other brands, using biogas from fermenters, syngas from gasifiers or just plain vegetable oil as fuel.

Zuccato Energia has several references in this field, and some of the heat-recovery ORC systems it installed have been up and running since 2011, a testimonial to their reliability.

The systems offered in this field, as all of Zuccato Energia ORC modules, are mounted on a self-supporting frame (“skid”) and are also available in a weatherproof, containerized version for outdoor installation..

Naval Engines

Strong in its multiannual experience in heat recovery from land-based gensets, Zuccato Energia has developed a range of ORC modules specially designed for heat recovery in the naval sector charcterized by par­ti­cu­lar­ly low operating temperatures regarding both the incoming thermal energy (≥86°C) and the cooling water in the condensation stage (≤20°C).

These systems – mounted on self-supporting skids as all Zuccato Energia systems – are further characterized by their compact dimensions, comparable with those of the gensets they aim to replace.