Alternative Fuels in Yachting: Promises and Pitfalls

The structure of a yacht is built to last decades. Shouldn’t the propulsion and energy systems be equally adaptable? The answer is yes according to Capt. Paul Brackley, the CEO of Central Yacht Limited. The company counts yacht design, project and build management, and operations among its services. At the same time, it combines the know-how from traditional maritime experience with forward-thinking solutions. To that end, Central Yacht is developing a patented modular energy-storage and propulsion architecture for yachts in the 49- to 66-foot (15- to 20-meter) range. It permits replacing or upgrading components throughout the yacht’s life, supporting future fuels without locking owners into one technology. Because there’s a lot of discussion about alternative fuels in yachting but little understanding, we asked him for an overview of what’s available, along with pros and cons for each.

Horse manure and alternative fuels in yachting may seem to have nothing to do with each other. But there’s actually an important common lesson. In the late 19^th century, forecasters warned that Manhattan would soon be buried under several feet of horse manure. More horses meant more waste, and the growth seemed unstoppable. However, they failed to account for the disruptive force of economics and innovation. When the internal combustion engine arrived, the problem simply vanished.

Similarly, alternative fuels are reshaping our industry just as dramatically as oil once did. I’ve spent nearly 40 years in the business, 10 as an engineer aboard some remarkable vessels, including one of the earliest “silent yachts” in 1993 with a 5-ton battery bank. I was also the owner’s project manager and captain for Ambrosia, the world’s first diesel-electric azipod yacht in 2003. I’ve therefore watched alternative propulsion evolve from curiosity to necessity. This gives me a healthy respect for innovation, and an equally healthy caution about the corresponding complexity, safety, and cost.

Methanol is gaining traction in commercial shipping. In fact, marine adoption is growing quickly. Nearly 60 methanol dual-fuel ships are currently operating, with hundreds more on order. Methanol is starting to appear—cautiously—on yachts. Builders such as Sanlorenzo, for instance, are integrating methanol reformers feeding hydrogen fuel cells. Lürssen’s Cosmos, presently conducting sea trials, employs them as well.Research programs like the FASTWATER Consortium, which includes Lloyd’s Register, have demonstrated safe bunkering and operation.

There’s more good news. Firstly, methanol is liquid at ambient temperatures. Secondly, it burns cleanly, with significant reductions in sulfur oxide emissions and particulates. But methanol presents its own challenges. Its energy density is roughly half that of diesel, meaning larger tanks are required for equivalent range. Pure methanol fires can burn with an invisible flame. Its toxicity further demands careful handling and storage. Safety protocols are stringent. Recent guidelines emphasize inerting tanks with nitrogen, double-walled piping, specialized detection systems, and extensive crew training. Retrofitting can be expensive as well, 20 to 30 percent above a conventional diesel system. Plus, bunkering options remain limited in key yachting hubs.

Hydrogen offers the enticing prospect of zero carbon emissions at the point of use. More yacht concepts rely on PEM fuel cells, which combine hydrogen and oxygen to produce electricity, water, and heat. The technology works—and works quietly. Several high-profile yacht and megayacht projects—Sinot Yacht Design’s Aqua concept (above), Lürssen’s hydrogen-enhanced proposals, and Hynova’s production day boat—prove the feasibility. Sanlorenzo has taken practical steps, supported by emerging infrastructure such as Monaco’s hydrogen yacht pontoon.

That said, hydrogen’s storage problems are formidable. Compressed gas requires pressures of 350 to 700 bar. Liquid hydrogen needs to remain chilled, at -423°F (–253°C). Both of these factors demand large, heavily insulated tanks that eat into valuable interior volume, increase weight, and complicate design. The fuel’s wide flammability range means detection, ventilation, and automated shutdown systems are mandatory as well.

Even with its benefits, adoption remains slow. Infrastructure gaps, high costs, and the need for highly trained technicians all stand in the way of widespread use.

Well understood in commercial shipping, LNG delivers meaningful reductions in emissions. LNG is natural gas in liquid form, which further dramatically reduces its volume. Nevertheless, it’s a cryogenic liquid requiring storage at about –260°F (–162°C), requiring significant onboard infrastructure. Boil-off, a.k.a. natural evaporation, of the gas is inevitable due to the effects of heat. So, commercial shipyards employ insulated tanks, vaporizers, gas-handling systems, and precise temperature management to control it.

While LNG dual-fuel vessels are increasing rapidly worldwide, yacht adoption lags. Leisure ports lack bunkering facilities. Above all, though, the space penalty is often the deal-breaker. Designers struggle to integrate the required equipment without compromising layout and comfort. Costs are mixed as well. Significant upfront investment runs 15 to 20 percent higher than diesel. Although operational efficiency and compliance benefits can offset that over time, that’s assuming adequate fuel is available.

Biofuels derive from renewable resources, offering perhaps the most straightforward path today. Many are drop-in replacements for diesel and can reduce lifecycle CO₂ emissions by up to 90%. Blends such as B20 are already used in superyacht trials with minimal modification.

The main limitations are availability and stability. Global supply constraints exist due to competition from the road and aviation sectors. Additionally, the fuels can degrade faster in storage. This is particularly a concern for yachts that may sit idle for months. Regular testing, appropriate additives, and proper tank management are essential.

Even so, biofuels may represent the most accessible near-term option for owners looking to reduce environmental impact without major technical upheaval.

All alternative fuels in yachting come with added complexity. A new-build owner might be willing to shoulder the cost and training. Still, what happens five or 10 years later, when the yacht changes hands? Experience unfortunately tells us that maintenance shortcuts creep in, through “deferred” service of classed systems or postponed inspections. Also, as technologies age, finding qualified technicians becomes harder. These create the possibility that a future owner, unaware or unable to maintain the necessary safety systems, ends up in danger. We must consider the entire service life of these yachts, not just their launch year. Ultimately, owners want reliability, quiet operation, and peace of mind just as much as efficiency.

As they say, watch this space. And when you’re at the dock, be careful where you step. Predictions have a habit of leaving horse manure in the road behind them.