Heat Recovery Micro Systems

       Thermodynamic Technology Development

Transport Sector

Rail & Road

A very large portion of CO2 and other greenhouse gas emissions originate from the transport sector, combusting fossil fuels for propulsion. The migration to electric propulsion is very slow, however, due to the weight and current cost of batteries. Transport propulsion systems therefore make researchers spend billions of dollars to increase efficiency and decrease emissions from internal combustion power units, but the progress is currently incremental, and not revolutionary.   

The introduction of REHOS technology would change that, however. The extremely high thermal to power conversion efficiency of  > 80% (see explanation in attached pdf file) could provide a propulsion unit converting the chemical energy in the fuel to electricity with an efficiency > 70% and using the final electrical motor drive chains for propulsion. At first, a small external combustion high efficiency liquid heater providing low temperature heat to the REHOS Generator may still use diesel, but at a much higher efficiency (about twice the current diesel engine efficiency used for transport propulsion. 

Using the current heat exchange technology as used by diesel powered vehicles, it would require a heat exchanger measuring 400 mm x 400 mm by 100 mm with a small fan forcing ambient air of 0,95 m3 / s through the exchanger to absorb 50 kW_thermal from ambient air at 25 degrees celsius to produce 40 kWe electrical power in a REHOS Generator, ready for vehicle propulsion. This kind of power pack would be very practical, as it can be used for electrical vehicle propulsion, but it can also produce electrical power for use in a household or building when the vehicle is not in use. The cooled airflow (heat extracted drop air temperature from 20 Celsius to 5 degrees) would then also be available for air conditioning in the same building! This would maximize the utilization of the REHOS Power unit for maximum return on investment!


Marine transport and freight depend for smaller craft, heavily on expensive marine diesel, while the larger ships use other fossil fuels like bunker oil to produce steam driven propulsion, also with a fair price.

Ships and marine vessels would benefit greatly when modular REHOS Power Generators become available, as these units would extract the required propulsion heat from the sea or river on which it is used. It delivers electricity to power modular pods providing electrical propulsion, completely doing away with the requirement for fuel of any kind. Using a liquid heat exchanger to absorb ambient heat energy is much smaller than air heat exchangers, due to the much higher density and heat capacity of water. This would revolutionize the marine transport and freight totally, as no cost component for fuel is part of the cost structure for marine transport any more.

Also, no combustion take place, making this propulsion solution also ideal for submarines, making batteries as well as diesel engines and fuel tanks obsolete! Marine transport would then also not produce any CO2 emissions into the atmosphere!


Serious research is already being done to change the airplane propulsion systems to electric. It was already proven that using an electric propulsion system for propelling a plane, have several advantages like eg. 30% lower power requirements with smaller lifting wings etc. Hybrid propulsion systems, where a gas turbine still supply the primary energy, but converted to electricity in a generator is already reality, while the use of the newest highest power to weight ratio batteries have also already been used to create aircraft of the future. The current biggest problem is the weight of battery systems.   

Using REHOS technology for providing the required electricity for propulsion is the answer with its high thermal to power conversion efficiency. A small external combustion low temperature high efficiency liquid heater, run initially from aviation fuel, but later possibly from liquid ammonia to produce the heat required by the REHOS Generator, supplimented by heat extracted from the air via a suitable heat exchanger. This solution have a chemical energy in the fuel to power conversion efficiency of 70%+, compared to the gas turbine efficiency around 10% (at take-off) and about 40% (at cruising speed and altitude). This huge difference would favor the REHOS technology, as the power to weight ratio would be more favorable, reducing fuel consumption drastically while fitting in perfectly with the future electrical propulsion systems for flight, currently being developed by researchers like NASA.