Developing a green solution for shipping

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The shipping industry is on a mission to become climate-neutral by 2050. For an industry that burns hundreds of millions of tonnes of oil-equivalent fossil fuel per year, this isn’t a simple process.

Denise Kurtulus, who heads our mtu marine propulsion business in Rolls-Royce Power Systems is convinced of a solution: “Green methanol has the potential to shape the energy transition in marine propulsion systems.”

Methanol is clean, efficient and can power ships in a climate-neutral way if produced using green electricity. However, its production and usage are not without challenges.

What are the pros and cons of methanol?

While methanal is a lot cleaner than conventional fossil fuels, it still releases CO2 when burned. Green methanol, however, is produced using a process where that CO2 is removed from the air during production, keeping the levels of CO2 in the atmosphere balanced.

Methanol has only around 50 percent of the energy density of diesel, meaning the tank volume must be twice as large as that of conventional diesel engines. On the other hand, it’s still much simpler to handle that other alternatives like liquid natural gas (LNG) due the fact it doesn’t need to be refrigerated.

Additionally, methanol is biodegradable and dissolves in water, which means there is less environmental damage in the event of an accident than with fossil fuels or ammonia, for example. Methanol is also less explosive than LNG or hydrogen. 

Bridging the gap to the energy transition

Our engineers are already testing methanol combustion with a technology demonstrator, working on parallel concepts for single-fuel methanol engines that only burn methanol and on dual-fuel engines. These are compression-ignition engines that can run on both diesel and methanol.

 

“In the long term, we see pure methanol single-fuel engines as the best solution,” explains Denise. However, she recognises that a dual-fuel engine will be needed to continue to support our customers in the medium-term.

“We see dual-fuel engines primarily as a bridging technology until green methanol is available across the board,” she continues. “However, the length of this bridge varies depending on the application.”

Yachts that call at ports all over the world, for example, will certainly rely on flexible dual-fuel propulsion for longer than ferry or tugboat operators who know their ports and therefore their fuel infrastructure. 

Global production of e-methanol

The Danish shipping company Maersk is already relying heavily on methanol. Not only has the company already put the first methanol-powered container ship into operation, but it has also ordered over 20 more such ships. And as demand increases, so does the production of green methanol. 

The world's first commercial plant for the production of green e-methanol started production in Kassø in southern Denmark at the beginning of 2025, aiming to produce 35,000 tonnes of e-methanol per year. 

In Anyang, China, CO2 methanol has been produced on a commercial scale for over two years now. Up to 110,000 tonnes of liquid methanol per year are produced here from carbon dioxide, which is recovered from the existing emissions from lime production.

In Germany, green methanol has been produced in a pilot plant since November 2023. Although this plant is smaller than those in Denmark and China, the production process is considered to be particularly cost-efficient.

While the development of green methanol solutions is important, we recognise that there will not be just one single solution for environmentally friendly ship propulsion systems in the future. Instead, various solutions based on renewable energies – including our mtu methanol engines – are needed.

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