Getting ready for prime time: high-speed methanol engine options

Two-stroke dual-fuel, slow-speed marine engines capable of operating on methanol have been available for a decade, racking up more than 600,000 running hours. This success has proven the viability of this low-carbon, alcohol-based fuel for use in the sector, with more options now commercially available from medium-speed OEMs.

But the first four-stroke, high-speed engines to burn methanol are just beginning to be introduced. With approvals from class societies in hand, engine designers plan to conduct extensive field tests of demonstrator models with the idea of making four-stroke methanol dual-fuel engines commercially available in the next three years.

One of those engine builders is Cummins. Dawn Wehr, executive director for strategy, product planning and digital for the Columbus, Indiana, OEM, says the company is “committed to providing solutions that work for different operations and fuel infrastructure availabilities to ensure ease of adoption.”

DNV awarded an approval in principle (AiP) to Cummins for its methanol-ready QSK60 IMO II and IMO III engines in June 2024. Designed with modular common-rail systems, these high-speed four-strokes are available in power ratings between 1,491 - 2,013 kW at speeds of 1,600-1,900 rpm.

Following field tests, Cummins plans to launch its methanol retrofit kit post 2028 “to align with market demand and infrastructure readiness.”

This project focusses on the conversion of existing engine installations, offering a simpler transition to burning zero- and low-carbon alternative fuels.

“There is a huge environmental benefit doing this”

Using green methanol, produced with renewable energy, offers significant environmental benefits compared to traditional marine fuels. It can reduce CO2 by 60-95% and NOx emissions by 60-80%, and virtually eliminate sulphur oxide and particulate matter emissions, according to the Methanol Institute.

Most of the currently available methanol is produced through steam reformation using natural gas as a feedstock. This fossil-based, grey version of the fuel is widely traded and used as a chemical component in solvents, plastics, paints and other products.

With an eye on futureproofing, Cummins says these new retrofit kits are designed for diesel-electric systems, and integration with battery technology. Battery-hybrid applications continue to grow, particularly in the offshore oil and gas and renewables sectors to improve efficiency, lower maintenance and cut CO2 and greenhouse gas (GHG) emissions.

Bibby Marine, for example, has ambitions to operate its new all-electric commissioning support operations vessel (eCSOV) entirely on batteries charged by renewable energy from offshore or shore-charging infrastructure to attain zero emissions when it is delivered in 2027. But the UK offshore vessel owner designed the eCSOV with operational flexibility to be powered by electrons or molecules. The 90-m vessel has 25 MWh of Corvus Blue Whale ESS, and two four-stroke Wärtsilä 3.48-MW W32 methanol dual-fuel engines.

Bibby Marine newbuild project manager, Gavin Forward, tells us that funding from the UK government allowed the owner to “put this big battery pack and a methanol fuel system [in place] to ensure that we can stay competitive with others delivering standard MDO vessels.”

Another consideration in the vessel’s design says Mr Forward are forthcoming taxes on carbon emissions resulting from regional regulations, the EU Emissions Trading System and FuelEU Maritime. 

“We look at the taxes coming in for the carbon and they are going to be around about US$100 to US$300 per ton. There are three tons of CO2 produced per ton of fuel consumed. So that’s a huge cost,” he said.