With CAT’s Methanol Engines, Sustainable Shipping is Possible

Recently, MarineNews sat down with Will Watson, Caterpillar Marine’s Product Manager, to discuss its rapidly emerging methanol engine development. Caterpillar Marine has already taken a considerable step forward in sustainability by planning to offer an upgrade kit for its methanol-fueled, dual-fuel Cat 3500E series engines. The immediate and long-term goal is to quicken the maritime industry transition to renewable energy.
The initiative, announced at an international tug & salvage trade event, aligns with the IMO 2050 target for a reduced-carbon future and the slowly developing market for lower-emission marine technologies. Caterpillar’s embracing of methanol as an alternative fuel in a dual fuel configuration is just one of many ways in which the company is responding to both regulatory requirements and customer demand for sustainable marine operations.

Defending Methanol and Leveraging Innovation

Methanol has been taken up quickly as a possible fuel for ships of all sizes, including commercial workboats, tugs, and inland waterway vessels. Its realistic storage capacity and energy density are very similar to diesel, so it is an achievable fuel solution for ships with fixed routes and established infrastructure networks. Or, in other words, the inland rivers and fixed route ferry markets.

“We are most focused on reliability and durability ... our customers know how our engine works on conventional diesel, and they want that same longevity and reliability on methanol,” – Will Watson, Caterpillar Marine’s Product ManagerWill Watson, global product manager at Caterpillar Marine, explains, “Everywhere in the maritime world, methanol’s been like, okay, this is a real thing. You get this reduction in greenhouse gas emissions ... more diesel-like than other fuels. Methanol requires less modification than hydrogen or LNG, but can be stored without much of a storage hurdle. It has less than half the energy density of diesel, so it’s perfect for small ships with space limitations, like a tug.”

Caterpillar Marine’s 3500E engine family well illustrates the company’s commitment to its signature of quality and reliability, even as it advances the application of alternative fuels. The methanol engines are engineered to produce as much power and fuel efficiency as Caterpillar’s conventional diesel engines. “We are most focused on reliability and durability ... our customers know how our engine works on conventional diesel, and they want that same longevity and reliability on methanol,” Watson said.

Converting these engines entails bringing cross-industry experience to the table, especially Caterpillar’s background in dual-fuel technologies from the oil and gas market. Indeed, Caterpillar’s reach across multiple shoreside, energy and marine market solutions is broad. Watson adds, “Our methanol engine is not like a blank canvas. It’s based on things we’ve been doing in other industries ... we’ve taken what’s been happening in some of our oil and gas world of dual fuel.” By using industry-tested technologies, Caterpillar’s methanol engines offer the kind of performance and safety standards expected from the industry.

The Cat 3516E Tier 4 Engine, methanol.
Image courtesy Caterpillar Marine

• “Our methanol engine is not like a blank canvas. It’s based on things we’ve been doing in other industries ... we’ve taken what’s been happening in some of our oil and gas world of dual fuel.” – Will Watson, Caterpillar Marine’s Product Manager
  
  

A major technical feat for the 3500E series is that it can be used on low-pressure fuel systems (less than 10 bar), allowing fuel flexibility without sacrificing power. The engines will reach very high methanol substitution, even at very low loads typical of tugs. “A 28-meter tug sailing at 8 knots, for instance, using just 600 kilowatts (kW) of propulsion energy, would aspire to achieve methanol substitution energy-wise greater than 70%,” said Watson. With this ability, operators can get substantial greenhouse gas (GHG) reductions with the same power they currently enjoy.

Modifications & Infrastructure Requirements

Moving from diesel to methanol as the primary fuel isn’t entirely straightforward; changes to the vessel’s fuel lines and fuel depots will have to be made. Methanol storage also requires independent tanks and other safety devices (e.g., a pump skid) to transport and bring fuel to the engine. “You’re going to need separate tanks ... today, you could just have common tanks with diesel fuel, but then in 20 years, you’ll have tanks with diesel and tanks with methanol,” Watson said. These requirements will remain with the same footprint for the methanol engines as for Caterpillar’s legacy diesel engines, making the switch more effortless.

Green methanol, also known as renewable methanol, is one of the biggest challenges in methanol adoption. As with diesel, methanol supply chains, particularly green methanol, are still in development, even though they are already in most ports worldwide. “The big issue is that green methanol infrastructure,” said Watson, indicating that customers will install methanol engines in their fleets, but green methanol availability will be what keeps the adoption moving. Hence, the question might be asked: ‘If they build it, will the customers come?’ Caterpillar is betting that they will.

“We want fuel flexibility for future-proofing assets. This technology will allow owners to take their fuel of choice at a time that works for them without constructing a new facility or paying costly retrofits.” – Will Watson, Caterpillar Marine’s Product Manager

Performance and Environmental Impact

With 3500E engines, marine operators will get reliable power as Caterpillar’s diesel engines without the extra emissions. “You’re not going to get a performance difference ... what we’re trying to do is, you’ve got a regular diesel engine, and you have our methanol engine, and you’re not going to get a performance difference on the response of that engine,” Watson explained. Renewable methanol provides the best environmental impact, vastly reduced GHGs over the entire lifecycle*. However, the environmental impact differs based on whether you use green, grey, or brown methanol. Watson recognized this struggle, continuing, “You won’t really start getting that global sustainability gain until you reach green methanol.” As green methanol production ramps, the company’s engines can help fleet operators adhere to and perhaps exceed increasingly stringent emission requirements.

Collaboration and Future Outlook

The latest development is that Caterpillar Marine entered a Memorandum of Understanding with the well-regarded Damen Shipyards Group to deliver the first methanol dual-fuel Cat® 3500E engines in 2026. “We’re taking our deep dual-fuel know-how to mitigate marine emissions,” adds Watson. This partnership will also help establish the actual efficiency of methanol-fueled engines in the marketplace.

Separately, Caterpillar has also worked with the Methanol Institute and Blue-Sky Marine as these industry bodies work to solve the regulatory, technical, and logistical challenges of methanol adoption. These alliances, among other things, aim to establish standard fuel specifications and create the infrastructure to have methanol available in all markets. To that end, explains Watson, “We’re increasing the fuel range of the 3500E platform so customers have more choices in how to move forward with the energy transition.”

The Journey to Fuel Flexibility & Future Innovations

The Cat 3500E line isn’t finished. In fact, this is more likely the beginning of a bigger story. The company plans to add methanol compatibility to more engine platforms, giving operators more options to lower GHG emissions in their fleets. Caterpillar expects a broader use scale across commercial and perhaps even luxury industries as green methanol infrastructure matures. Watson touts the future of this effort, saying, “We want fuel flexibility for future-proofing assets. This technology will allow owners to take their fuel of choice at a time that works for them without constructing a new facility or paying costly retrofits.”

Caterpillar has also pushed for non-regulated emissions reduction as part of its holistic policy. This IMO III-compliant 3516E engine technology can be operated under both regulated and non-regulated emissions and still offers the same after-treatment space claim as the old model, demonstrating the company’s commitment to total environmental solutions. And, in a workboat industry where internal space savings are an all-important part of vessel design, this part of the Caterpillar journey is especially relevant.

Caterpillar Marine: the Cutting Edge of Sustainable Marine Power

When Caterpillar Marine begins bringing its first methanol-fueled engines to market, it will open the door to a sustainable, more available future for marine propulsion – for all workboat operators. The Cat 3500E engine family brand values innovation, dependability, and environmental sustainability, which is well-understood in today’s competitive landscape.

With continual collaboration, a drive for fuel scalability, and a future focus on platform growth, Caterpillar’s methanol engines stand ready to shepherd the marine industry into the next significant evolution. Watson summarizes Caterpillar Marine’s vision for sustainable shipping, insisting, “We’re constructing a product that needs to satisfy our reliability and durability expectations ... we’re developing a product that needs to satisfy the customer’s value benefit expectation to take us there.” And, that’s just the kind of industry partnership that’s destined to succeed.

* GHG emissions at the tailpipe are essentially the same as those of traditional fuels.