Lurssen, MTU team up on methanol-fuelled superyacht engines

Lurssen has teamed up with Rolls-Royce Power Systems to build a motor yacht fitted with an MTU engine that will run on “green” methanol as a fuel source.

Green methanol is a synthetic fuel made by taking carbon dioxide from the atmosphere and converting it using solar or wind-generated electricity. According to Larssen, the amount of carbon dioxide emitted by the engines using the fuel “s equivalent to the amount originally extracted from the air, resulting in a 'net zero' carbon footprint”.

Why methanol? According to Rolls-Royce Power Systems, while methanol presents its own problems – you need about 2.4 times more methanol than diesel to provide the same amount of energy – it requires significantly less space than other alternatives such as hydrogen for fuel cells or batteries with the same range.

It is also less toxic than ammonia, a noxious liquid used to transport hydrogen that can then be used for powering fuel cells or for feeding into a traditional internal combustion engine.

Of note, methanol is also less expensive to produce than other forms of synthetic fuel.

“For Rolls-Royce, a high-speed methanol-fuelled engine for the marine industry is one of many solutions that form our net zero strategy, and is currently being developed by our MTU brand,” Rolls-Royce Power Systems said.

“Despite differing fundamentally from diesel in many chemical and physical parameters – from energy content, density, evaporation properties and ignition energy to viscosity and lubrication behaviour – the team can draw upon extensive experience with other liquid fuels, primarily taken from diesel engines.”

According to Lurssen, methanol has the greatest potential for motor yachts stretching more than 75 metres in length.

“Our customers want to dedicate as little hull space as possible to propulsion and fuel storage,” Lurssen chief executive Peter Lurssen said. “Methanol has disadvantages here compared to diesel, but clear advantages over other alternatives to fossil fuels.

“We're now seeing that today's prospective buyers of tomorrow's yachts are increasingly thinking about how they can make running their vessels as environmentally sustainable and climate-friendly as possible,” he said.

“We are therefore registering a growing willingness among future customers to invest in new technology for climate protection, and to make space available for it in the vessel.”

Rolls-Royce is developing a methanol engine based on the 4000 horsepower-plus 69-litre V16 MTU Series 4000, an engine typically used for high-speed motor yachts and low loads.

Unlike diesel engines, which ignite the fuel using high pressure, methanol’s lower flash point means it will need to be ignited using a spark plug, in much the same way as a conventional petrol engine.

Italian manufacturer Sanlorenzo also has jumped on methanol, and is planning a yacht with methanol-fuelled MTU engines “in the coming years”.

Lurssen believes its biggest challenge with the fuel is convincing owners of the benefits of methanol. To counter that, it plans on building a methanol-fuelled generator to handle the power needs at one of its shipyards to demonstrate the technology. It will also use the heat generated by the engine to warm its workshops.

Rolls-Royce MTU engines and a battery-fuelled hybrid electric system will also soon be built into a 76-metre Turquoise Yachts megayacht due to be commissioned in 2025 for delivery in 2026.

MTU plans to launch a fuel cell system for superyachts in 2028.