Graduation thesis – Lars Steverink Delft University of Technology

Metal hydride cooling systems for fishing vessels

Lars Steverink, a student at delft University of Technology, has successfully defended his graduation thesis. Lars has researched the thermal powering of metal hydride cooling systems for fishing vessels in Stellendam in consultation with the H2GO project Shipping.

Sustainable replacement
Metal hydride cooling systems can provide cooling by allowing hydrogen to flow through the system and may use residual heat for this purpose. This makes it a sustainable replacement for the current system. ‘Conventional’ metal hydride cooling systems are now being investigated to be used in the form of air conditioning, but the current study has looked at the technical possibility of replacing the presently used ice slurry refrigerator.

Developed computer model
To investigate this, Lars developed, validated and then tested a computer model with a new metal hydride powder. The final conclusion is that the reactors will weigh about 500 to 700 kilograms on the flyshooter ships for a cooling capacity of 16 kW, excluding the water network and pumps. More research needs to be done on low temperature metal hydrides to better understand the precise possibilities and cooling performance.

Fuel cell
The calculated system is “closed”. Hydrogen is trapped in the reactors. Another interesting possibility is the “open” metal hydride cooling system, to which a fuel cell and a hydrogen tank are connected. Hydrogen then flows through the cooling system from the storage tank to the fuel cell. The high pressure of the stored hydrogen then drives the system and no residual heat will be needed. Such a system is therefore also suitable for ships that sail fully electric. Another advantage of this is that the number of reactors can be halved and therefore the system weighs only half, compared to the “closed” system.

Price and duration
An important characteristic for the final use of such systems are the price and the still needed development time. Unfortunately, there is no answer to these questions from this research. The research area is currently small and the prices of different metal hydride powders seem to vary greatly. As a result, it has not been possible to make a good estimate in the study. The ongoing research in various places around the world to replace air conditioning in cars with a metal hydride system does give hope that it could be possible in terms of price in the future.