Experience with methanol fuel

Apr 21 2022


Capt. Kanchan K. Mukherjee, Director Operations, NYK Bulkship (Asia) presented his experience with methanol fuel.

NYK Bulkship of Singapore operates the Takaroa Sun, an oil and chemical tanker (IMO Type 2), which can run on either conventional fuel or methanol.

 

Capt. Kanchan K Mukherjee, director of operations with NYK, discussed his experience with methanol, speaking at the DNV Alternative Fuels conference in October.

 

The vessel was built by Hyundai Mipo, and chartered to Waterfront Shipping in September 2019.

 

It has a MAN B&W engine, supplied ready for water-methanol blending, with a scrubber.

 

Between delivery of the ship in Sept 2019 and Sept 2021, the vessel had clocked around 5000 running hours on methanol, and consumed 6,000 metric tonnes of fuel.

 

The vessel was awarded a ‘special mention’ in the category “Green Ship of the Year” of the Singapore International Maritime Awards 2021, organised by the Maritime and Port Authority of Singapore.

 

Two more vessels will be delivered in Feb 2022 and Apr 2022.

These vessels have a “Pilot Oil Fuel Ignited in Water” (PIFIW) system which lowers the NOx level in the emissions, which eliminates the need for a scrubber.

 

Methanol basics

Methanol produces up to 15 per cent less CO2 than conventional fuel during combustion. This is less than LNG, which emits 25 per cent less CO2. But methanol is much easier to handle than LNG, being a liquid at under 64 degrees C. As with LNG, there are no sulphur oxide emissions.

 

Its volumetric energy density is less than half of diesel, so it requires fuel tanks more than twice as large for the same energy output. The pipeline systems need to be double walled.

 

There have been methanol carrying tankers which have used their cargo as a ship fuel since 2014. The world's first barge to ship methanol bunkering was carried out in Rotterdam in May 2021.

 

Globally, there are 12 methanol fuelled ships in operation and 20 more on order. It is available in almost 90 of the top 100 ports with minor modifications to existing bunkering and storage infrastructure, we heard in the webinar.

 

In future, it is envisaged that methanol could be produced from green (renewably sourced) hydrogen combined with biogenic CO2, such as collected from combustion of organic material. This would mean the whole cycle was ‘net zero’ since the CO2 would have been taken from the atmosphere.

 

But availability of methanol is still very low compared to the supplies that would be needed.

 

Crew training

“The first challenge for operations comes in crew training,” he said.

 

All crew except galley staff were required to undergo training in the basic IGF code (International Code of Safety for Ship Using Gases or Other Low-flashpoint Fuels). The master also undergoes an advanced IGF course.

 

Masters, before being given a command, are required to serve a month on an LNG, methanol or other low flash point fuel vessel, including witnessing 3 bunkering operations. If the advanced training includes simulator training, they only need to watch one actual bunkering operation.

 

However, the “ME-LGIM” engines proved to be very user-friendly for crews, he said.

 

Set-up

On the Takaroa Sun, the fuel supply system, service tanks and slop tanks are all located on deck, kept segregated with a fuel valve train.

 

The methanol fuel supply line is double walled, with a gas detection system and nitrogen purging.

 

Methanol is supplied at 8-10 bar, and injected at around 600 bar. This is similar to conventional oil fuelled engines, he said.

 

A 40 bar (high pressure) sealing system ensures no methanol is leaked in the injection system.

 

The quality of methanol is benchmarked to standards from the International Methanol Producers and Consumers Association (IMPCA).

 

The methanol needs 5 per cent pilot fuel, because it has a low self-ignition quality.

 

The second and third vessels operated by NYK have a “Pilot Oil Fuel Ignited in Water” (PIFIW) system which delivers pressurised water to be mixed with the methanol, which reduces NOx emissions to meet Tier III levels.

 

There is a safety system which monitors methanol injection and combustion, and if there are any alarms, it enables a seamless switch to low sulphur fuel oil or low-sulphur marine gasoil.

 

The vessel has a fuel conditioning system, known as a “Low Flashpoint Fuel Supply System (LFSS)”, provided by Alfa Laval. This has a panel providing easy identification of functioning / operation of various components during draining, purging of methanol, he said.

 

Experience

During the first 2 years of using the engine on methanol, no major failures were experienced with the main engine, he said.

 

There were some minor problems, which Captain Mukherjee described as a “Fuel Booster Injection Valve (FBIV) cut off shaft failure, a LGI (liquid gas injection) Connector Piece Seal ring damage, an LGI Connector Block Sleeve seal damage, and scrubber failures during operation due to IP converter and flow meter".

 

To resolve these problems, the LGI connector was replaced with an improved design and a seal with different material, filters were installed in the air line going to IP converters, he said.

 

On a non methanol voyage, it is recommended to run the main engine on methanol for at least an hour a day, to avoid "seizing of cut-off shafts inside the nozzle".

 

The CO2 emissions during the period were calculated at 24942 tonnes, where it would have been 26813 tonnes without methanol, so a reduction of 7 per cent. Theoretical minimum emissions, if methanol was used for all voyages and auxiliary engines, could have been 23404 tonnes, so a reduction of 13 percent.

 

In terms of the final economics, there was a marginal increase in OPEX for maintenance and training. However maintenance may become easier than with conventional fuel as the technology matures. It is very important to monitor liner lubrication, wear, and “scrape down analysis” (iron content in scraped oil), he said.

 

“The future of methanol certainly holds good.”

 



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