Safety by design – Engineering the future fleet: Daan Buitenhuis

From the magazine – Engineering a liquid hydrogen-powered powertrain of a foiling boat involves more than designing and building it. Daan Buitenhuis and the powertrain department of the TU Delft Hydro Motion Team are working hard to make it functional in time for the Monaco Energy Boat Challenge.

This article is part of our Young talent series “Engineering the future fleet”. This article was first published in our June 2026 issue. All articles in this series are written bij SWZ|Maritime editor Bas Lenferink. All photos by the TU Delft Hydro Motion Team.

Engineering the future fleet is back at the TU Delft Hydro Motion Team. The assembly of the hydrogen-powered and foiling boat is finished and testing has started in approach to the Monaco Energy Boat Challenge in July. I’m meeting with Daan, chief powertrain engineer. He is responsible for the team that engineers everything that involves energy; from energy coming from the hydrogen tank until it is high voltage electricity that reaches the motor.

Daan is 22 years old and finished his bachelor’s degree in Mechanical Engineering at the TU Delft last year. From a young age, he was working on little projects and interested in engineering: ‘I always tried new things, making lamps, repairing bicycles and making something out of nothing. As a little kid I always said that I wanted to be an inventor.’

From his high school where he finished technasium, a project and technology focussed VWO, he could see the tower of the EWI (Electrical Engineering, Mathematics and Computer Science) faculty at the TU Delft. He soon decided that the TU Delft was where he wanted to study. Daan’s role in the Hydro Motion Team fits in well with the career he has in mind.

‘I am thinking of pursuing a master’s in Mechanical Engineering: Energy Flow and Process Technology next year. The Dream Team gives me the opportunity to get some experience on the topic. Besides that, I like that it is a big project, bigger than my own little projects. With more money and more possibilities. When I finish my studies, I want to work in the innovation sector and make the world a better place. I would like to do so in the green energy sector. This year really adds up to that.’

Also read: Pushing boundaries – Engineering the future fleet: Casper Koopman

From chemical to electric

Everything from chemical energy towards electricity powering the electric motor is the responsibility of the powertrain department. ‘We start at the hydrogen tanks. Hydrogen flows through regulators and safety mechanisms to a fuel cell. Here, a high voltage current is produced, which is stored in a battery. The battery then drives the motor. From there on the vehicle dynamics team takes over.’

Making a so-called boil-off management system to dispose of pressure buildup from hydrogen gas in the liquid hydrogen tank is the team’s biggest challenge this year. Last year was the first year the team worked with liquid hydrogen and a lot of hydrogen gas had to be vented off. This brings safety concerns, because you are not able to vent hydrogen gas everywhere.

‘Liquid hydrogen has a temperature of 20 Kelvin and is stored in an isolated tank. Because the tank is not cooled, hydrogen gas boils off as the liquid hydrogen heats up. Pressure in the tank is beneficial for a gas flow to the fuel cell, but when it gets too high, the gas has to be vented,’ Daan explains.

For the boil-off management system, hydrogen gas is turned into electricity: ‘With our new system, we want to direct this gas to a smaller fuel cell of 500 watts (a 40-kilowatt fuel cell is used for the propulsion). This smaller fuel cell then charges a battery and an excess of electricity is delivered to the power grid, just like a solar panel. In the future, we want to build a device with resistors, that can turn the electric energy into heat and therefore lose the energy on board. Making it safe to use in for instance a harbour.’

Scale and energy needs

Systems can be designed having the boil-off in mind. That is where Daan sees an opportunity for the use of liquid hydrogen: ‘Big container vessels or oil tankers have a near constant energy use when sailing. You can design the systems to boil off less than needed. In that case, there is no excess gas that you need to dispose of and the flow can be regulated easily. Besides that, the tanks are round and if you double the size of a tank, the volume increases to the power of three. Which makes it more energy efficient, because the surface area increases less than the volume. Scale plays a big part.’

Another big part of the powertrain are the batteries. Just like a hybrid car, they can provide consistent power when demand peaks. ‘Energy conversion in the fuel cell is a mechanical process. It takes a few seconds before it is running at full power if needed. So, when the boat is accelerating during a race, the batteries can provide for the peak demand. Then, during the race at about 54 kilometres an hour, the maximum speed, the fuel cell produces 40 kilowatts. This is just a bit more than the motor needs and the battery can be charged.’

Also read: Liquid hydrogen as the fuel of choice

Pressure build ups and high voltage

Safety is high on the agenda for the team, or as Daan puts it: ‘It’s one challenge to make it work, the other is making it safe.’ The team has developed protocols to ensure safety.

‘We always try to think through everything that could go wrong and what would happen in that case. In theory, using liquid hydrogen is a basic thermodynamic process and to the tank, there is only a regulator and a pipe attached that goes to the fuel cell. But covering for big pressure changes or faults is the challenging part. The same goes for the high voltage system. In theory, it is not that different from a low voltage system, but 400 volts is coming from the fuel cell and 700 volts is going into the motor. That is a dangerous current. Making that safe to work around is my biggest concern.’

Confidence in the design comes from discussing with others and thinking everything through, says Daan. ‘We were new to the topic at the start of the year. We had a lot of help from companies and our predecessors. Walking through all scenarios and working with the theory makes you confident.’

Every year, improvements are made based on the previous design. Some improvements come from an unexpected field. ‘We are gradually integrating more and more safety standards from the electric car industry. For instance, the shutdown of the whole system when a high voltage cable is unplugged.’ Daan thinks it is important to share knowledge in the industry: ‘Not all companies produce papers on their innovations. I think it would help taking steps faster and improve everyone.’

The team is now in the testing phase, taking place on the Wantij near Dordrecht. The team does not just start sailing on liquid hydrogen, a testing schedule is made. ‘We first start by sailing on battery power and test all built-in safety features. Only then do we start with hydrogen gas, with liquid hydrogen being the last step.’

The coming weeks are dedicated to more testing. The race will take place in Monaco in July. After the race, SWZ will return to the team one last time, to discuss the results.

Picture (top): Daan Buitenhuis: ‘When I finish my studies, I want to work in the innovation sector
and make the world a better place’ (all photos by TU Delft Hydro Motion Team).

Also read: VIDEO: Hydro Motion Team reveals 2026 hydrogen boat