YachtTalk episode 11: The future of yacht propulsion

The 11th episode of Heesen’s YachtTalk deep dives into the topic of how to develop yachts with cleaner, more efficient propulsion. Hydrogen remains a focal point, but there are plenty of effective short-term solutions to meet emissions targets. To meet the requirements, however, the industry first needs to fundamentally change the way we approach energy in yachting. Host Charlotte Kan is joined by Tobias Kohl, director of Application Engineering for Marine at MTU/Rolls-Royce Power Systems – a leading expert in the field of hybrid drive systems and exhaust after-treatment solutions – and Pieter Dijkstra, owner of Green Tech Invest, an independent consultant for electric energy systems, and a pioneer in marine hybrid propulsion.

Forerunners
In 2021, MTU/Rolls-Royce Power Systems celebrated the 25th anniversary of its Series 2000 and Series 4000 engines, the first of which were installed on board Heesen yachts. Liaising with and educating owners and shipyards on the possibilities around cleaner propulsion systems is part and parcel of Tobias Kohl’s daily routine. He points out that much of what we rely upon in the marine industry has been learned from the automotive sector.

“Most of the technologies that we have on board yachts today have come from automotive,” says Kohl. “From exhaust after-treatment systems to hybrid installations, these types of innovations happened in the car industry first. Our job is to transfer those developments to the marine industry and make it fit the relevant market needs.”

There are, of course, differences between the two sectors, adds Kohl, highlighting brake energy recovery as an example of something that does not translate from automotive to yachts. The niche properties of yachting, compared to automotive’s mass market opportunities, also present challenges. “That’s where we need to further develop standards within yachting and learn from one another and transfer applications rather than developing one-off unique models for individual yachts.”

Pieter Dijkstra highlights subsectors within the maritime industry, from tugboats and ferries to inland vessels, as well as the aviation sector as being at the forefront of change. “Aerospace is going electric too and there is a lot of ongoing development there that can help the yacht industry,” he points out.

Hydrogen
Regarding clean propulsion, all eyes are on hydrogen fuel cell technology. Kohl believes it is “the most important energy carrier of the future” as we can produce hydrogen on a green, renewable basis. The main challenge is the capacity to store large amounts of energy on board a yacht. “That’s why the use of methanol fuel cells, which are able to operate with reformer technology and then be combined with a methanol combustion engine, could be the future,” he says.

Dijkstra agrees, saying: “Hydrogen is a building block to come to a sustainable solution. It’s not only the yacht that needs to carry fuel – there is an energy need and refuelling requirement in the destinations where the yacht is heading, too. In that instance, liquid fuels might be a more logical solution than gas, allowing the yacht to become an energy supply to remote areas where it’s difficult to have sustainable infrastructure, such as small Caribbean islands or locations with hot climates.”

Both experts conclude that the end result will be a form of energy mixing. “There is not just one fuel that fits everything,” says Kohl, “but we have the chance right now to influence how that happens for the future.”

New strategies
Forming part of MTU’s new strategy, Kohl highlights the three key pillars that will go towards making yachts cleaner in the next few years. “First, we need to look at efficiency, including how today’s diesel engines are used, after-treatment systems and waste-heat recovery systems. Second, we need to combine electrification and hybridisation on yachts – at present, both elements are completely independent from one another. And third, out net zero strategy means we must develop our engines further to be ready for sustainable fuels and have a clean, holistic approach; that is, zero CO2 in the atmosphere.”

Talking through a scale model of MTU’s hybrid system, Kohl highlights some of the benefits and key features, including meeting new emissions requirements, the newly developed electric motor – which gifts the option of powering a yacht entirely on electricity, as well as recharging the batteries on a long-distance cruise.

“Our approach is for this to be a modular system,” says Kohl, “which delivers standardised interfaces, all pre-tested in our facilities, and just one point of contact within MTU.”

Heesen has taken its own step towards sustainable yachting with the launch of BlueNautech, which it unveiled at the 2021 Monaco Yacht Show. It consists of six pillars: hull efficiency, propulsion efficiency, energy saving at anchor, sustainable operations, alternative materials and sustainable production methods.

“We are taking this step by step, but Project Sapphire’s optimised hull, newly launched Galactica’s pitch propellers and battery pack, and our hybrid propulsion system are all examples of what we’re already achieving,” says Sjoerd van Herk, senior naval architect at Heesen.

Future endeavours
A pioneer in the world of electric drive train solutions, Dijkstra introduced a hybrid engine system as early as 2006. “Today, we’re still busy finding new ways, smaller sizes, lower footprints and better components,” he says. “We’re still finding new solutions, getting into the heads of designers and to the heart of what owners truly want from their yachts.”

Heesen’s award-winning yacht Home was the first boat from the Dutch shipyard to have a hybrid propulsion system. Going forward, Dijkstra believes it is the new generations that are pushing for hybrid solutions: “I think that push is becoming stronger and stronger, and in the end there will only be hybrids or full-electric yachts. Regions around the world are becoming less accessible for full-diesel vessels.”

Kohl agrees, adding: “Hybrid allows clients to enter protected areas with their yachts, there are definitely customer benefits in the technology. I also think there is an expectation from both the market and society to see the yachting industry set standards and be cleaner for the future.”

Tune in for the next episode of YachtTalk.