Boating’s Fuel of the Future?

In the race to clean power, electricity is in the lead.
But how do we generate the necessary juice on board without burning fossil fuel?
One superyacht builder has an answer.

We all love our internal-combustion engines—our ICEs—but even the newest and cleanest-burning of them produce greenhouse gases (GHG) that contribute to global warming. In 2023, ICEs are the bête noire of the environmental folks, and if they have their way, by the mid-2030s, we’ll all be driving electric cars, like it or not. But what about our boats? Will we also have to replace our gas and diesel engines with electric motors? Battery power is fine for mooching around the harbor, mostly at slow speed, but how will we get the range we want for cruising and fishing offshore if they take away our ICEs, given today’s battery technology? Nobody carries a yellow cord that long. Maybe there’s a better answer.

Compared with the exhaust of fuel-burning power stations, factories, cars, trucks, trains, planes, ships, lawn mowers, leaf blowers and so forth, the amount of GHG (CO2, methane and nitrous oxide) produced by pleasure boats is a pittance. Europa.eu says that shipping accounts for about 3 percent of total GHG emissions from all sources. But most of the emissions come from ships, not yachts: According to the International Maritime Organization, yachting accounts for just 0.22 percent of greenhouse gas emissions for the entire maritime sector, or not quite .007 percent of the total emissions from all sectors. Boat owners are small potatoes in the battle against global warming, so even if we throw all our ICEs overboard in favor of electric motors, what difference will it really make? Well, any reduction in GHG emissions, however minuscule, is a positive step for the planet, so it behooves all of us keep an open mind about reducing our carbon footprint.

Some yacht builders are ahead of the carbon curve: Greenline has been building hybrid-drive boats since 2008, using onboard diesels coupled with electric motors for propulsion, with solar cells for passive recharging at anchor. The electric motor is used mostly for short-range, low-speed cruising, with the diesel at hand for recharging and faster passagemaking. Azimut says its new Seadeck series of hybrid motoryachts will reduce CO2 emissions by 40 percent over a year of average use, including cruising and time spent at anchor.

No Free Lunch

The shipping industry is also working to reduce emissions. In 2011, the IMO instituted mandatory measures to reduce GHG emissions from ships, which traditionally burn high-sulfur, molasses-thick bunker oil—some of the nastiest stuff imaginable. The goal is a 40 percent reduction in CO2 emissions by 2030 and 70 percent by 2050, compared to the 2008 level, and a reduction in total GHG emissions of 50 percent. One way of achieving this is by replacing hydrocarbon fuels with biofuels produced from sustainable feedstocks (organic materials that can be used as fuel or converted into fuel) using sustainable energy sources. Biofuel production requires energy and emits GHG, the amount depending on how the fuel is made, and there are many methods, using different feedstocks and sources of energy. But refining crude oil takes energy and produces pollutants, too. Thus, the goal is an overall reduction of GHG from production to consumption of biofuel vs. the GHG produced from extracting, refining and burning fossil fuels to produce a similar amount of energy. (When it comes to energy, there’s no free lunch. How much extra fuel will be burned, and extra GHG produced, to meet the demand for electricity when entire neighborhoods plug in their EVs at the same time? Ideally, it will still be substantially less than the GHG emissions produced from fossil fuel powered cars.)

Biodiesel and ethanol are the biofuels most people are familiar with, but methanol (wood alcohol; don’t drink it) is also a source of relatively clean energy. Methanol is fairly cheap to produce relative to other alternative fuels, according to the U.S. Dept. of Energy, less flammable than gasoline and can be produced from a variety of organic feedstocks. In a fuel cell, the methanol isn’t burned, but electrolyzed to produce electricity. “It’s also one of the most readily available (bio)fuels on the market, supplied in around 100 ports,” according to an R&D engineer for Sanlorenzo.

Sanlorenzo is planning a new model, the 50Steel, to be built at their Spezia, Italy shipyard and launched in 2024. The 164-footer will carry an array of methanol fuel cells that will power all the “hotel” systems—essentially everything except propulsion. The client for this innovative new yacht is Massimo Perotti, Sanlorenzo’s CEO.

Energy Without Ignition

Fuel cells create electricity through galvanic action, similar to the way a battery works—but instead of storing and discharging electrons, a fuel cell generates electron flow from a fuel, usually hydrogen. Like a battery, fuel cells have an anode and a cathode, separated by a polymer electrolyte membrane (PEM) similar to a thin piece of plastic wrap. When hydrogen is introduced to the anode side, a catalyst, generally a platinum coating on the anode, encourages the hydrogen atoms to split into protons and electrons. The PEM allows the protons to pass through to the cathode, but the electrons must travel through a wire from one side of the cell to the other. En route, they supply electricity to whatever appliances are in the circuit. Once the electrons reach the cathode, they rejoin their protons, and combine with oxygen from the atmosphere to form water molecules. Thus, water is the only byproduct of a fuel cell, making it a very clean source of power.

So where do you get hydrogen? Although it is the most abundant element in the universe, hydrogen is rarely found on its own; you have to extract it from other compounds—with the right technology, you can electrolyze hydrogen from water. Or you can get it from methanol: A reformer fuel cell, like those designed for Sanlorenzo by Siemens Energy, separates hydrogen from the other components of methanol, carbon and oxygen; only hydrogen ions will pass through the fuel cell. The carbon and oxygen are discharged as carbon dioxide—so this type of fuel cell isn’t as clean as one using pure hydrogen. However, the volume of CO2 produced is much less than a fossil-fuel generator would exhaust to make the same amount of electricity.

“The reformer transforms the methanol into hydrogen at the same time as the fuel cell is producing energy,” said the Sanlorenzo engineer. “This avoids having free (and explosive) hydrogen within the boat. The hydrogen is already in the fuel cell component.” Some reformer fuel cells operate at high temperatures—some even use steam to break down the methanol­—but the modules for Sanlorenzo, built by Advent Technologies, operate at normal pressure and only slightly higher than ambient temperature. “There are no particular safety issues associated with high temperature or pressure.” (At press time the system was undergoing the risk-analysis procedure conducted by Lloyds Register to certify the installation.)

Recycled Water

Sanlorenzo’s fuel-cell system will consist of 20 modules, generating a healthy 100 kW in total. This will be enough electricity to cover the 50Steel’s energy needs, said the company engineer. “The energy produced by the cells isn’t stored, but used immediately. There are lithium-ion batteries on board with a capacity of around 600 kilowatt-hours (about 7 Teslas worth), but they are used only to buffer peak energy demands.”

The 50Steel will carry 1,320 gallons of methanol, enough for about a week of full-load operation when mixed with distilled water at a 60/40 ratio. Water is a necessary component of the fuel that feeds a reformer fuel cell. Both the water and the methanol must be absolutely clean—any contamination will degrade the performance of the fuel cell and shorten its life. The water vapor produced by the reformer will be passed through a condenser and reused in the fuel cell. Thus, none will even be discharged overboard.

Unlike hydrogen, which is stored at up to 10,000 psi pressure, liquid methanol is carried safely at atmospheric pressure in conventional tanks. “Although it’s a fuel that can be likened to petrol or diesel,” said the Sanlorenzo engineer, “it requires a dedicated tank that’s different from normal fuel tanks, and is classified differently by current regulation.” Sanlorenzo is conducting research into adapting methanol tanks for use aboard the 50Steel.

Will projects like the 50Steel save the planet? Not a chance. It’s going to take a lot more than just methanol reformers, EVs and hydrogen-powered cars to clean up the atmosphere. Even if we all surrender our ICEs today, you and I will be boating on the River Styx long before the planet sees noticeable improvement. But it’s a start towards our children’s—and grandchildren’s—future, and maybe it will inspire other builders, especially those who deal in less-than-mega yachts, to take similar steps. It can’t hurt, can it?

Methanol as Propulsion

Methanol reformers aren’t just for powering ships’ systems; they can be used to spin propellers, too. The Elliott Bay Design Group in Seattle has designed a towboat for Maritime Partners of Metairie, Louisiana, with methanol reformer propulsion. The M/V Hydrogen One is the maritime industry’s first IMO 2030-compliant long-range towboat, according to Elliott Bay. (IMO 2030 standards represent a 40 percent reduction in CO2 emissions vs. 2008 levels.)

Engineered by e1 Marine in Bend, Oregon, the fuel cell in the 90-foot towboat can generate 1,700 continuous horsepower, enough to drive the Hydrogen One at 5.5 knots for four days or 478 nm before refueling; top speed is just over 8.5 kph. This doesn’t sound like much by Power & Motoryacht standards, but remember: This is while pushing barges full of cargo. Lithium-ion batteries can also be brought online for up to six hours for a substantial horsepower boost when needed; a conventional 150-kW Caterpillar genset recharges them. ABB Marine & Ports designed a power management system that balances the sources of power as necessary.

The reformer fuel cell consumes about 35 percent less energy and produces 28 percent less CO2 than a diesel generator of similar output along with zero particulates, zero nitrous oxides and zero sulfur oxide emissions according to the Elliott Bay Design Group. It’s “ideal for anything that requires continuous power over extended periods, including work boats and medium-range passenger vessels.” It might also make a nice, diesel-free power package for a coastwise-cruising trawler yacht, as long as a reliable source of methanol is available.

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This article originally appeared in the August 2023 issue of Power & Motoryacht magazine.

Source: https://www.powerandmotoryacht.com/boats/boatings-fuel-of-the-future