Methanol as a marine fuel is increasingly becoming a viable contributor in shipping’s drive for a clean, sustainable fuel mix, and is providing the experience necessary for the development of stronger marine fuel standards on the seaward journey to decarbonization, says an article published on maritime executive website.
Methanol as fuel
Methanol as a marine fuel has potential thanks to its simpler handling and lower investment infrastructure costs. Using methanol produced from natural gas offers a proven reduction of NOx and SOx emissions, and by producing methanol from renewable sources, shipping can substantially reduce its GHG emissions.
As with other new fuels entering the market, the concerns of shipowners and other stakeholders are focused on safety, fuel availability and meeting future GHG requirements. One of the main challenges to owners during this fuel transition is to decide on an alternative fuel or fuels to prepare for 2050.
IMO guidelines
In November 2020, the Maritime Safety Committee of the International Maritime Organization (IMO) adopted interim guidelines on the use of methanol as a marine fuel, making ethyl and methyl alcohols options for shipowners and operators. 12 methanol powered ships are already in operation, with another 10 on order.
Early adoption of any new fuel depends on the demand and the supply landscape. In the case of methanol, even though its trade is well-established globally with more than 70 million tons produced annually, its use across many applications and industry sectors may restrict the actual volume available for the shipping industry unless incentives are introduced. This could mean methanol being produced synthetically, which could incur extra costs.
Benefits
Methanol has the advantage of a liquid state and the ability to re-purpose existing infrastructure, to include engines and vessels with efficient retrofits. Onboard containment of methanol is easier than LNG, though the liquid fuel has a lower volumetric density than LNG, necessitating comparatively larger containment tanks.
Methanol could be made 100 percent renewable, as it can be produced from a variety of renewable sources such as biomass or electrolysis powered by renewable energy. This makes it a strong candidate fuel for a sustainable future in which shipping is powered by 100 percent renewable fuels.
Fuel Properties
Methanol is a colorless liquid at ambient temperature and pressure with a characteristic pungent odour. It is easier to store and handle than liquefied natural gas (LNG), ammonia and hydrogen fuels. Its properties are shown in Figure.
Methanol’s specific energy of 19,700 kJ/kg is much lower than that of LNG and conventional liquid fuels. For the same energy content, methanol requires about 2.54 times more storage volume than conventional fuels. When comparing methanol to LNG, an overall decrease in the effective volumetric density of LNG is to be accounted for due to packaging factors for cylindrical tanks, insulation and filling factors, boil-off gas, and custody transfer losses.
Regulatory Approval
The general safety principles of the IMO’s IGF and IGC Codes provide the framework for the use of low-flashpoint marine fuels such as methanol. Common safety principles such as fuel tank protective location, double barriers on fuel supply lines, ventilation and gas detection, hazardous area classification, explosion mitigation, etc. are equally applicable to all low-flashpoint fuels.
The recently-adopted IMO Interim Guidelines for the Safety of Ships Using Methyl/Ethyl Alcohol as Fuel covers considerations for ship design and arrangement, as well as fuel containment system, materials, pipe design, bunkering, fuel supply, power generation, fire safety, explosion prevention, hazard area classification, ventilation, electrical installations, control systems, crew training and operations.
In addition to methanol being traded and transported in chemical carriers for many years, there is also the experience of the Offshore Support Vessel (OSV) and Platform Supply Vessel (PSV) fleets handling methanol for the offshore industry, which can also be reference points for the wider adoption of methanol as a bunker fuel.
Vessel Applications
The adoption of low carbon and net carbon-neutral fuels for large vessels is more challenging than for smaller ones. Using fuels with low energy content, such as methanol, would require a significant redesign, not least because their fuel tanks would need to be expanded to store enough energy for longer deep-sea travel.
However, methanol is more suited to storage in near-conventional fuel tanks which can be easier to accommodate in ship designs than other low-flashpoint fuels, and under MSC.1/Circ.1621 5.2.1 can also be bound by a vessel’s shell plating when stored below the lowest possible waterline.
Near Term Potential
The benefits of reduced emissions from burning methanol could be a significant contributor to reducing greenhouse gas emissions from the maritime industry. Existing methanol trade infrastructure can also be an important factor for the cost and availability of methanol over other alternative fueling options.
Using methanol as a fuel in methanol carriers for propulsion and power generation, along with the development of efficient and feasible dedicated propulsion systems, has already created an increase in newbuild cargo vessels powered by methanol. If methanol is produced renewably, these tankers could have an even greater potential to reduce life-cycle emissions while concurrently improving the renewable methanol fuel supply chain for other applications.
Summary
- Methanol as a marine fuel is increasingly becoming a viable contributor in shipping’s drive for a clean, sustainable fuel mix, and is providing the experience necessary for the development of stronger marine fuel standards.
- Methanol as a marine fuel has potential thanks to its simpler handling and lower investment infrastructure costs.
- In November 2020, the Maritime Safety Committee of the International Maritime Organization (IMO) adopted interim guidelines on the use of methanol as a marine fuel.
- Methanol could be made 100 percent renewable, as it can be produced from a variety of renewable sources such as biomass or electrolysis powered by renewable energy.
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Source: maritime executive
