A boat is an energy island when sailing. Recover waste heat that come from the generation of on board energy, both mechanical and electrical, increases energy efficiency and results in a saving in fuel and cost during sailing. The added advantage in this application is that sea water is used in the HRU system to cool the condenser, which means it is not necessary to implement any additional cooling system (tower, aero) as occurs in most inland applications.
This aspect, combined with the growing cost of fuel, means that the system has a much reduced pay-back.