Rolls-Royce confirms methanol engine development

Batteries, he said, are not the best option for Crew Transfer Vessels (CTVs), and he also ruled out hydrogen and ammonia as potential fuels.

“We believe in methanol for high-speed and long-range applications,” he said. “Energy density is about half that of diesel, better than most of the alternatives. We are sure that green methanol will become significant in the future.

“We are developing the technology right now for methanol combustion engines, and it could be single fuel or dual-fuel combustion engines. What we see at the moment is the availability of methanol in the ports is quite limited, so we are waiting for a clear signal from the market.

“We are sure that green methanol will become significant in the future, and we will provide methanol engines in the future.”

When it comes to CTVs, however, size matters, he said – and the smaller the vessel, the less appropriate a methanol solution would be.

“With 35-metre CTVs it’s much easier to implement than in the 25m vessels but we don’t know what the future will bring, to be honest,” he said. “There’s pressure to decarbonise in the offshore wind market so I can imagine there will be a lot of dual-fuel engines in the market, but it also depends on the availability of the fuel.

“If it’s a dual fuel you can just go back to diesel but there will be a trade-off. You either optimise for diesel or you optimise for methanol. It will not be possible with a high-performance engine to switch from 100% methanol to 100% diesel.”

In conclusion, Gommeringer said methanol was the best alternative to diesel for the CTV market because:

• Batteries are not an option for high-speed vessels with long ranges
• Hydrogen systems are too complex and heavy, with low energy density
• Ammonia is too toxic and probably only suitable for deep-sea shipping
• ‘Drop-in’ fuels such as E-diesel and HVO are attractive, but had availability and cost challenges.

Going electric

CTV developer Tidal Transit is a firm believer in electric propulsion for getting to, from and around wind farms, and director Leo Hambro told Maritime Journal that quite simply, it was the most efficient way to do it.

“Obviously Rolls-Royce sells engines and therefore are not going to be supporters of batteries,” he said. “The very simple facts are electrical propulsion is the most efficient; electrical propulsion has lower maintenance costs and downtime; our clients produce electricity where we go every day that can be used to charge the boats.

“Offshore Wind is the one of the few marine sectors (like ferries) that can already work with electric vessels. This is opened up even more by offshore charging.”

“Today’s batteries are quite big and heavy,” said Gommeringer. “This is especially an issue for fast vessels and vessels with long ranges. However they might be an option if energy density improves a lot; the wind park is very close to the shore; vessel speed can be reduced.

“Of course offshore charging would help to go with batteries. But with today’s battery technology I assume this would still just be possible for very few CTVs. This would need to be checked case by case.”