The Future King of Green Shipping Fuels: Is Methanol the Superior Choice?

With the maritime industry producing 3% of all global greenhouse gases (GHGs)¹ and the IMO setting a shipping emission reduction target of 70% by 2050, methanol’s rise to stardom as an alternative fuel is not surprising. Experts even suggest it’s in a unique position to be the mainstream renewable fuel type across the international shipping industry.

But methanol isn’t the only low-emission fuel on the horizon. Ammonia and, to a lesser extent, hydrogen could be two viable pathways to decarbonising the shipping industry in the future.

Is Methanol the Superior Green Shipping Fuel of Choice?

The advantages methanol has to offer as an alternative, low carbon fuel type are plain to see. Shipping companies are already aware of them, as there are now over 20 dual-fuel methanol tankers in operation. And thanks to the IMO’s Interim Guidelines for The Safety of Ships Using Methyl/Ethyl Alcohol As Fuel (MSC.1/Circ.1621), more methanol-driven vessels are expected to grace the open seas in the future.

But what makes methanol so special compared to other low emission fuel types? Does it come with any disadvantages?

 

Protects What’s Above – and Below

Methanol is a biodegradable fuel type and poses fewer climate and environmental risks.

Unlike diesel and gasoline, pure methanol combustion emits no sulphur oxides, reduces nitrogen oxides (NOx) by up to 60% depending on the engine, and produces minimal particulate matter and CO2². Injecting water into the combustion chamber can reduce NOx emissions furthers by lowering peak combustion temperatures and diluting oxygen.

It’s also biodegradable and dissolvable in water with a half-life of 1-7 days, which significantly reduces environmental pollution in the event of spillage³.

Ammonia doesn’t fare quite as well. Despite lower CO2 emissions, it has high nitrous oxide output upon combustion, producing reasonably high greenhouse gas emissions⁴.

But above all, it’s highly toxic and potentially deadly to humans. Incorrect handling and leakage incidents pose a risk to crew. Even air concentrations of 30 parts per million (ppm) can cause respiratory problems in a short amount of time. Significantly higher concentrations can cause irreversible damage or death⁵.

 

Flammability and The Need for Proper Storage

Correct methanol tanker storage, handling and transportation conditions are imperative to vessel and crew safety. The same goes for other alternative fuels like ammonia and hydrogen.

Methanol is extremely flammable. It has a low flashpoint of roughly 9-10°C, making it highly ignitable and susceptible to spark or flame-related explosion incidences⁶. Its vapour pressure is also high, sitting at roughly 13 kPa at temperatures of roughly 25°C, meaning it’s prone to evaporation and flammable vapour buildup at room temperature.

By comparison, ammonia is non-flammable but can ignite at temperatures exceeding 600°C or in the presence of other substances.

Vessel owners need to consider these risks. By employing the correct storage conditions, adequate ventilation and sophisticated valve systems, vessel and crew casualty risk can be virtually eliminated.

But what are the costs of preparing a ship for methanol use?

 

Cost Considerations

Nearly half of all operational vessels must be retrofit for methanol fuel and other zero emission fuel use to achieve complete shipping decarbonisation by 2050. And considering there are other carbon reduction targets before 2050, and a typical vessel’s lifespan is 25 years, widescale retrofitting must happen as soon as possible⁷.

But transitioning from high-emission fuels to low-emission methanol comes with some additional costs.

According to a recent report, the upfront cost of converting a high-emission fuel oil vessel to a methanol-enabled one is roughly 10-16% the cost of a newbuild tanker, amounting to USD 15-24 million depending on the preparation level. Retrofitting vessels for ammonia is 19-26% (USD 47.5-65 million)⁸.

 

Integrating Safety Valves into Methanol Storage

Installing the right safety valves offers long-term protection for shipowners, their crew and their methanol-ready vessel. But it all comes down to which valve solution they choose. And how compliant they are according to the recent MSC.1/Circ.1621 rules regarding valve specifications on methanol ships.

Many inline pressure-vacuum (P/V) valves cannot prevent the passage of flames or function unobstructed without a flame arrester, posing a risk of toxic methanol fume leakage into storage or living areas, potentially endangering the crew.

We design our end-of-line high-velocity valves as pressure vacuum release devices and flame arresters in one combined solution, capable of dispersing toxic methanol fumes upwards away from the vessel without obstruction or leakage into storage or living areas.

Each valve outlet functions at least three metres above-deck, six metres above a gangway and 10 metres away from living areas, ignition sources and other openings in accordance with MSC.1/Circ.677. This protects crew from dangerous methanol leakage and explosion-related incidences.

And they’re a cost-effective solution, as they’ve already gone through an endurance burn test and are certified in compliance with IMO MSC/Circ.677, as well as the amendments presented in MSC.1/Circ.1324 and MSC/Circ.1009.

 

Is methanol the future king of green fuel?

Methanol is gradually emerging as the leading fuel option for shipping and marine companies compared to other low-emission fuels like ammonia and hydrogen, thanks to its minimal carbon output, reduced environmental pollution and lower upfront retrofitting costs compared to ammonia.

Limited technology and official IMO guidelines for ammonia also make methanol out as the preferred option for ship owners. However, we should keep in mind that strict measures are vital for storing methanol safely due to its high flammability. That’s where proper ventilation and valve systems can help minimise any risks.

 

¹ https://ec.europa.eu/research-and-innovation/en/horizon-magazine/emissions-free-sailing-full-steam-ahead-ocean-going-shipping

² https://www.methanol.org/wp-content/uploads/2020/04/IMO-Methanol-Marine-Fuel-21.01.2016.pdf

³ https://www.methanol.org/wp-content/uploads/2016/06/White-Paper-The-Fate-Transport-of-Methanol-in-the-Environment-1999.pdf

⁴ https://www.sciencedirect.com/science/article/pii/S1743967122002069

⁵ https://www.ncbi.nlm.nih.gov/books/NBK207883/

⁶ https://www.icheme.org/media/9915/xviii-paper-32.pdf

7 https://www.globalmaritimeforum.org/content/2022/03/Insight-brief_Retrofitting-ship-engines.pdf

⁸ https://cms.zerocarbonshipping.com/media/uploads/publications/Preparing-Container-Vessels-for-Conversion-to-Green-Fuels.pdf