Hydrogen is often seen as a major player when it comes to alternative energy, but it takes real world applications to show not only its strengths, but also its shortcomings that will need to be overcome if it's to have widespread application, much less form the basis for an entire economy.

Launched on May 4, 2024, Project 821 is intended to push hydrogen technology to its limits as it relates to superyachts. This is particularly important because there aren't any regulations for storing hydrogen or in regard to fuel cell systems at class, flag-state, or even IMO level. As a result, Feadship had to work with superyacht brokers Edmiston and Lloyd's Register to come up with not only the scaled technology for ships over 100 m (328 ft) in length, but the prospective protocols and regulations.

Hydrogen fuel cells have been around ever since they were used on the Apollo Moon missions during the Space Race but they've never had much of any application in the maritime sector – at least, not on any large scale.

Project 821 illustrates some of the hurdles still to be overcome. Even in such a large ship, hydrogen is hard to deal with. Though the gas is a very efficient energy source, it has a tenth of the density of diesel fuel and has to be stored under pressure at -253 °C (-423 °F).

For Project 821, the ship has to carry over four tonnes of hydrogen to run 16 fuel cells through special switchboards to deliver DC power. This doesn't even touch on problems like hydrogen embrittlement of metals that such systems are prone to or the special vent stacks to handle the venting water vapor, which required lengthening the hull. On top of this, the ship has to be able to carry easier to store methanol to feed the fuel cells for when hydrogen isn't available.