Analysis of “green” fuels for the maritime industry


The world is changing, and the transport industry has to take drastic measures in order to contribute to the reduction of CO2 emissions. Maritime transport with its time-consuming Shipbuilding industry has to plan ahead for the “green” ships of tomorrow. While oceangoing ships are already the most energy efficient means of transporting large amounts of cargo over long distances, the current level of emissions from shipping will no longer be considered acceptable for decades to come. Alphaliner shares its analysis of green fuels for the maritime industry: the pros and cons of methanol, ethanol, LNG, ammonia and hydrogen.

Even though, it is recognized that the environmental footprint of the shipping industry, including CO2 emissions, sulfur oxides and particulate matter, is quite small in relation to the huge volumes of cargo carried around the world. However, in absolute numbers, the adverse effects are large due to the sheer scale of the maritime industry.

As a whole, shipping accounts for about 3% of carbon emissions caused by human activities. Therefore, the International Maritime Organization (IMO) aims to reduce CO2 intensity (relative to the amount of cargo carried over a given distance, measured against a 2008 baseline) by at least 40% by 2030 and is making efforts to reach 70% by 2030. 2050. Some operators even plan to go beyond this and have committed to becoming ‘net zero’ by 2050.

Nowadays, there is an industry-wide consensus that the IMO targets must be achieved, and the idea of ​​reaching net zero within the commercial lifetime of a single generation of ships, around 25 years, has gained a lot of attention, and force. However, there is no clear consensus on the path towards this goal.
An important step in the right direction is ensuring that new containership builds are as flexible as possible when it comes to new types of alternative fuels.

recently, we have seen the adoption of LNG as a cleaner fuel that significantly reduces emissions of sulfur oxides and soot. While LNG ships emit less CO2 than comparable conventionally powered ships, they do not solve the greenhouse gas problem, according to Alphaliner.

Conversely, Alphaliner states that some scientists even claim that the problem of “methane creep” — small amounts of unburned gas escaping into the air — completely eliminates any advantage LNG would have in terms of its carbon footprint. This is because methane gas itself is a powerful greenhouse gas.

Currently, Alphaliners denotes that there are seven more or less realistic options for powering a large main ship over long distances. These are compliant fuels, HFO fuels for ships equipped with scrubbers, LNG, methanol, ethanol, ammonia, and hydrogen. Some of these fuels can be obtained in three ways: from fossil deposits, as biofuels, and through the power to X (PTX).

The latter means that electricity is used to synthesize combustible fuels from atmospheric CO2 and water. For PTX fuels to be “green,” the electricity that runs the chemical processes must, of course, come from a carbon-free source, such as solar, wind, hydroelectric, or, somewhat controversially, nuclear.

Based on the findings of a recent joint study by OCEANS ONE and GMW Consultancy, Alphaliner today looks at the pros and cons of some of these new fuels when applied to a large container ship (type ‘Megamax-24’).

The expected bunker costs for alternative fuels will be significantly higher than the bunker costs incurred based on the average costs of the last ten years. Bunker costs for biofuels will be at least a factor of 2.5, but most likely a factor of 4.0 higher than in the past.

Below, Alphaliner looks at five alternative fuel ships: LNG, methanol, ethanol, ammonia, and hydrogen. All of these are ‘in principle technically feasible today. However, each new fuel comes with its own challenges along the way.

Below, is the Analysis of “green” fuels for the maritime industry according to Alphaliner for the new building of ships with the current technology:


LNG is already a well-known fuel in the shipping industry and many Liners are aligning their strategy toward LNG propulsion. Due to the expansion of the LNG fueling infrastructure, switching to LNG is a suitable solution to meet various future emissions requirements, even when using the fossil variant of the fuel. However, the decision in favor of LNG is associated with significantly higher investment costs on the one hand and some operational challenges on the other.

Due to the low storage temperature of -163°C, all fuel handling equipment must be designed for cryogenic temperatures, and special ventilation requirements, as well as large, well-insulated tanks, drive up investment costs. In addition, from an operational point of view, the amount of evaporation gas generated by the tank that must be burned in the generator if the main engine is at high pressure must be taken into account. Therefore, energy-saving measures such as a power take-off or a waste heat recovery system do not make sense.


Methanol as a fuel offers several advantages over LNG as an alternative to existing fuels. Due to its storage temperature under normal ambient conditions, cryogenic equipment is not required, although special fuel processing equipment must be provided. The somewhat higher cost of a suitable main engine and generator engines must also be considered.

Compared to LNG, methanol has a lower specific energy density. However, since classification society regulations allow fuel to be stored between HFO-like bulkheads, but surrounded by some cofferdams to adjacent spaces, container slot capacity losses caused by methanol tanks will be lower than for LNG carriers and the cost of capital will also increase. be shorter
Given that synthetic methanol has a very high net CO2 savings potential, as well as an existing commercial infrastructure, it is definitely one of the best options for decarbonization.


Like methanol, ethanol can be stored under normal ambient conditions and no cryogenic equipment is required to handle the fuel. Therefore, the additional cost of the ethanol tank is likely to be of the same order of magnitude.

Since the specific energy density is slightly higher compared to methanol, the required tank space can be reduced to achieve the same operational flexibility as all other vessels in the comparison. So there is no loss of container space with this solution.

The only downside to the fuel is that it will most likely only be available as a biofuel and the net CO2 emission reduction potential is lower compared to PTX alternatives, even if the fuel can meet all future emissions requirements. .


Ammonia is being discussed as one of the most powerful alternative fuels for decarbonizing shipping, but it faces some challenges when considered to power a container ship.

Not only does it need to be stored frozen at -33°C, but it is also highly dangerous to health. Requirements for safe shipboard operations drive up capital costs, and finding the necessary trained personnel also drives up operating costs.

Furthermore, to ensure adequate operational flexibility, very large tanks are required, with corresponding capital expenditures. However, when considering ammonia from PTX sources, CO2
reduction potential outweighs fuel challenges. Because there is no carbon atom in the chemical formula, no CO2 is released when the fuel is burned. This is its big advantage over the fuels mentioned above, which can only deliver their CO2 reduction potential on a net basis.


Considered by some sources to be the ultimate solution to the world’s energy (transportation) problem, hydrogen still has some unresolved challenges when considering its application in an MGX-24 class ship.

Although the CO2 removal potential is the best compared to other fuels, the low specific energy density of hydrogen means that a tank of unprecedented size must be provided on a container ship.

It is not enough, the storage temperature is -253°C with a suitable cryogenic system. Apart from the fact that a suitable tank system in that size has not yet been developed, the thickness of the insulation would be at least 1.2 meters and thus the slot losses would be considerable.

The expected investment cost for such a system will easily be a third of the total price of the boat or even more. Despite the unsurpassed CO2 reduction potential, hydrogen as a fuel does not appear practical for large-scale use in an MGX-24 class container ship so far.


According to Alphaliner, the alternative fuel landscape is a vast field with many options. Shipowners face the challenge of choosing the right fuel to decarbonize their fleets according to their respective strategies. While some fuels are already available with the right infrastructure, others offer greater emission reduction potential at sometimes higher or even significantly higher investment costs.

Operational challenges and likely fuel availability must also be considered. For owners of large tonnage containers, the advantage is that the ships operate on a few selected main routes. Therefore, only the availability of fuels along the main route should be considered, rather than the global availability.

Looking at the expected costs of bunker if ships run on just one of the new low carbon or near carbon fuels, it becomes clear how high the prices are for 100% decarbonisation, even if this would mean a hefty over-compliance. . with the next regulatory framework of the IMO or the European Commission.

However, the aforementioned standards will lead to a more or less significant increase in bunker costs over time. Considering that in the past bunker costs accounted for around a third of slot costs per loaded container, it is clear that in the future fuel costs will be a major factor for container shipping around the world.

Thus, the investment costs will no longer be as important as the availability and prices of the right fuel. Vertical integration, cooperation, and joint development projects for fuel supply will be solutions for a viable decarbonization strategy and will determine the future success of shipowners.”

Source: Alphaliner

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