So How Does Hydrogen Power Work on a Yacht, Anyway?
We're not engineers, but the growing body of evidence regarding hydrogen's potential can't be ignored any longer
As the transition from conventional gas-power and new-age electric power continues, a quiet but effective third option is emerging.
Today's news is full of headlines about the ongoing transition to electric power. While there is certainly merit to its inevitable arrival, there is also an undercurrent questioning its current viability. Such are the ebbs and flows of progress.
There are obvious benefits to reducing emissions and providing net-zero manufacturing that electrification or alternative fuel sources can provide, but as it stands today, there is still ground to be made up in terms of range, capability, and value. At present, gas power still resides atop the marine propulsion heap. But electric power is rapidly climbing.
While that emerging market undergoes its evolution, there is a quiet dark horse showcasing major potential for marine propulsion.
We've discussed it before. Several major shipyards have been tinkering with the technology for years. Names like Lürssen, Feadship, and Sunseeker, for starters. Even gas-engine manufacturers have devoted significant resources towards hydrogen development. Names like Yamaha and Toyota.
There have even been some radical designs with undeniable potential.
Now the early labours of hydrogen advancement are beginning to bear fruit.
In March, Lürssen launched their first ever hydrogen-powered superyacht for a Japanese customer. It's legitimately impressive -- they designed their own fuel cell that utilizes the conversion of methanol to hydrogen to generate enough power for the secondary systems on a 314-foot ship. The superyacht, dubbed Project Cosmos, can travel up to 1000 miles at a slow cruise using stored hydrogen.
The problem for outsiders and non-engineers, however, is that it's never been particularly clear how hydrogen works on a yacht.
The average boating enthusiast who isn't an engineer or marine technician is left scratching their heads -- how is it different than gasoline?
Before you can advocate for something, you must first understand it.
Of the currently available examples of hydrogen-powered yachts, shipbuilders have been clear that their systems are complimentary -- they work in conjunction with diesel, solar, electric, or some combination thereof.
Most hydrogen fuel cell technologies being applied to boats take liquid hydrogen stored in tanks and distribute it over an assembly of individual membrane electrodes to produce electricity. Once the electrification process is complete, the power is either assigned to a ship's propulsion system to turn the engine or, depending on the ship's design, to battery banks for future use. There are variations in the process, some of which use methanol or ammonia in place of hydrogen, but the end goal is the same -- to store an alternative to fossil fuel onboard that can generate electric power.
This still begs the question -- how can we integrate hydrogen fuel cells and battery banks onto yachts? Furthermore, can they be made small enough to fit on the average recreational boat? If so, will they be safe?
Some of the best new evidence comes via Dutch shipyard Feadship, who announced their own proprietary hydrogen fuel cell. Thanks to some informative graphics and information provided by the company, the average boater can now get a clearer picture about how hydrogen power is designed and applied in the marine world.
Jan-Bart Verkuyl, Feadship Director and CEO of Royal Van Lent Shipyard, stated in a LinkedIn post regarding their new project: “The yacht will house a cryogenic fuel tank, storing liquified hydrogen at around -250°C, being the densest storage method of pure hydrogen. This fuel cell bank will be sufficient to sail at a decent speed while still powering the hotel load in summer conditions."
The graphics provided by Feadship make the design more clear:
In a recent blog post from Bram Jongepier, a Senior Specialist for Feadship at De Voogt Naval Architects, stated: "Without sacrificing luxury, size, freedom and all the other reasons to build a yacht, efficiency can be raised by 20, 30, maybe 40%, but at some stage we’ll have reached the maximum of what is technologically feasible; laws of nature cannot be cheated. The only way for further reduction is to change our fuel."
Jongepier also added, "in the not-so-far-away future, methanol and hydrogen will be part of the available sustainable fuel marketplace. Of the current methanol and hydrogen on the market less than 5% is produced sustainably, but these percentages are expected to rise fast. Maritime type approved dual fuel engines and fuel cells will be available in a couple of years, so new Feadships (with a very conservative estimated lifespan of thirty years) are now built to cope with that changing fuel marketplace."
Some of the major lingering questions about hydrogen power are: Can it be installed in vessels besides superyachts? Can it generate enough power to make gas/diesel obsolete? And perhaps importantly: can it be stored safely?
Feadship's design appears to include a series of 4-5 generators placed in the bottom of the hull next to a cryogenic storage tank. Since the storage space required for hydrogen is significantly higher than a typical diesel engine arrangement, Feadship has factored its storage requirements into the hull design. The hydrogen, which must be kept at a frigid -250 Celsius under pressure, has been placed at the base of the hull, which will presumably change the vessels center of gravity (as compared to diesel fuel tanks). This may provide later opportunities for advancements in ship design because conventional weight distributions will have to be entirely reconsidered. Once the power is generated it's sent to the nearby generators for immediate use, or to batteries for later use. The storage requirements for lithium batteries will also affect hull design, weight distribution, and storage capacity.
The Feadship design will be a template for the future. But according to experts, the existing regulations regarding hydrogen storage may be the biggest barrier to advancement.
Laurent Perignon of Energy Observer developments’ maritime division told the Superyacht Times: “A major difficulty we face is that current maritime legislation – or rather the lack of it – limits compression to 350 bar as opposed to the 700 bar for cars. This poses a problem because at 300 bar the hydrogen storage tanks on a yacht need to be around fourteen times bigger than equivalent diesel tanks and five times the weight. At 700 bar we could at least reduce the volumetric mass by half.”
If pressurization can be increased, which reduces storage space, then using hydrogen on smaller vessels becomes more realistic. If hydrogen fuel systems can be similarly sized to current gas/diesel configurations, then their adoption potential increases even more, especially among smaller vessels. And lastly, if hydrogen can be stored safely under pressure while producing zero emissions, then its viability increases even more.
One lingering detail that currently affects the above statement is redundancy. Given the need for cold temperatures and high pressure, current systems can't be used in isolation. Marine regulations forbid it, which is why hydrogen's earlier pioneers are using a combination of hydrogen, gas/diesel, and even solar power to offset the risks.
Will we see hydrogen power on small boats in the near future? All signs point to yes.
There are kinks to be worked out, but the engineering capability of superyacht shipyards is continuing to lead the charge on behalf of the recreational boating market.