Why Is Methanol Poised to Help Transform the Maritime Industry?

Meeting Maritime Application Demands

There are multiple types of methanol. Most methanol commercially available today is produced using natural gas or coal as a feedstock and is referred to as gray or brown methanol, respectively. Blue methanol is produced using natural gas that has been produced through steam reforming. Green methanol, sometimes referred to as e-methanol, is produced using hydrogen derived through a renewable energy supply.

Compared to marine diesel, methanol can help lower CO₂ emissions as well as nitrogen oxides (NOx) and sulfur oxides (SOx)² although it’s important to note that formaldehyde can potentially form during methanol combustion, which could have safety and environmental impacts.³

Methanol also has a lower energy density than diesel but a relatively high energy density compared to hydrogen, and it can be stored as a liquid at standard conditions. These two crucial advantages are essential to minimizing ship design and operational range impacts. As large cargo vessels are beginning to make transcontinental journeys using methanol,⁴ this lower-carbon intensity fuel appears to be able to satisfy both safety and range considerations for marine applications.

Methanol is globally available today as a common chemical used in many industrial processes. Its existing infrastructure, as well as well-documented safety and handling procedures, supports the use of this extremely efficient hydrogen carrier as a lower-carbon intensity fuel for maritime applications. The primary challenge with using methanol fuel in today’ diesel engines is that it can’t ignite under compression and requires an external ignition source, such as a cetane enhancer, spark ignition or diesel pilot. Currently, only dual-fuel engines can enable methanol to provide a comparable performance to diesel, which is especially well-suited to the growing interest in marine fuel flexibility.

Methanol Complements Other Energy Sources

Methanol can play a critical role on its own as a future maritime fuel, and it can also be used with other lower-carbon intensity fuel options. While a dual-fuel engine requires diesel as the ignition energy, traditional diesel may be replaced with hydrotreated vegetable oil (HVO), biodiesel or any blend of such fuels to further reduce carbon intensity. Methanol can also be used to power generator sets that act as battery chargers in a battery hybrid installation. The myriad of possibilities affords vessel operators greater flexibility.

Over the past 20 years, Caterpillar has invested more than $30 billion in research and development (R&D). The company has also established cooperative R&D agreements with several universities and governments to leverage learning within the industry and share knowledge in academic spaces. One recent example is Caterpillar’s cooperation with the U.S. Department of Energy’s Oak Ridge National Laboratory to evaluate methanol’s use as an alternative fuel in marine engines.⁵

The methanol-ready Cat^® 3500E marine engine represents a notable example of maritime technological advancements. In 2022, Caterpillar Marine announced that the 3500E can be modified to run as a dual-fuel engine using methanol.⁶ In 2024, plans were revealed to deploy the first set of field demonstrator methanol dual-fuel 3500E marine engines with renowned shipbuilder Damen Shipyards.⁷ The engines have been optimized for high methanol substitution rates across a wide range of load factors.⁸ For example, a typical harbor tug could achieve a methanol substitution of greater than 70%, on an energy basis, demonstrating the significant potential benefits methanol can provide to such an operation.⁹

Navigating Climate-Related Objectives

The transition to a reduced-carbon future presents a range of opportunities for vessel operators. In many cases, it’s possible to achieve fuel flexibility that accommodates methanol without needing new builds or costly retrofits. Ship operators can review their unique circumstances and consider the benefits of adopting methanol and other solutions to help achieve their climate-related goals and address evolving industry requirements.