European Maritime Day: Sustainable Alternative Fuels and Shipping

, by Kelly Schwarz

European Maritime Day: Sustainable Alternative Fuels and Shipping
Credits: pexels Selective Focus Photography of Fuel Station

Today is European Maritime Day. The subject this year is ‘Sustainable blue economy for green recovery’ [1]. When talking about improving the sustainability of the maritime sector, an important topic is the future of alternative sustainable fuels.

Gas is perceived to be an alternative fuel by many businesses and political actors to achieve the ambitious climate goals of net-zero by 2050 in Europe, as stated in the European Green Deal. Gas in its liquid form, also called Liquefied Natural Gas (LNG), is seen as an alternative fuel for ships and has already been deployed by many ship owners. The use of LNG as ship fuel is also expected to rise, given the focus in the Fit-for-55 package on promoting LNG as a shipping fuel.

The European Union recently proclaimed gas to be a sustainable energy source. Gas has some advantages as it does emit fewer CO2 emissions than other fuels, has an established distribution network and relatively low costs.

However, gas is not a clean energy source. LNG is still a fossil fuel and has limited potential for greenhouse gas (GHG) emissions reduction of 10% compared to conventional ship fuels, and is already leading to a rise in methane, which is a dangerous GHG emitter and is “over 80 times more warming than carbon dioxide”. The problem with natural gas being declared a sustainable fuel is that it will lock in fossil-fuel LNG for the next decades because ships have a 10-20 year operating life span. Just recently, Transport & Environment, a non-profit organisation that focuses on advocating for cleaner transport in Europe, released this paper that shows the detrimental effects of ships using LNG as a fuel.

Biofuels are another fuel that is seen as a promising alternative. Biofuels can be derived from crops, algae and non-edible crops such as waste. It is also closer to being commercially viable compared to other sustainable fuels, as will be mentioned below. Biofuels have the ability to lead to reductions in GHG emissions and pose less of a risk to marine life when spilt into the ocean. However, there are problems with producing it sustainably. The fertiliser, water, and land necessary to generate enough biofuel to significantly reduce fossil fuel usage might cause other issues, such as increased pollution and decreased food access.

It is advised by many academics and NGOs to invest in and promote e-fuels (also called synthetic fuels) instead of LNG and biofuels. E-fuels or synthetic fuels are fuels produced from electricity. There are already many different fuel options, however, at the moment ammonia, bio-based methanol and hydrogen are declared to be “the most promising carbon-neutral fuels”.


If produced with renewable energy, hydrogen is the cleanest fuel of all the other alternatives. Hydrogen does not emit CO2 emissions, if it is produced with renewable energy, making it one of the most environmentally friendly alternative fuels for shipping. There are, however, some drawbacks with hydrogen, such as its storage which requires around six to ten times more space compared to conventional fossil fuel. Other problems are the high cost of storing the hydrogen and insufficient infrastructure for hydrogen supply to ships. Hence, in the near future, hydrogen is mostly only an option for short-distance shipping and ferries that can provide a steady supply of local fuels.

Also, hydrogen should be produced with renewable energy. If it is produced with fossil fuels, it will continue to emit carbon dioxide. Now, hydrogen is frequently created using fossil fuels, which release a significant amount of carbon dioxide. Another problem with this production method is the leakage of methane.


Ammonia produced via renewable energy is a promising source for deep-sea shipping. It is cheaper than batteries and unlike hydrogen or LNG, its storage is easier. However, it has several disadvantages, such as the need for significant expenditure on renewable energy production capacity and bunkering infrastructure to replace fossil fuels. Ammonia’s exhaust cleaning technology is still being perfected, therefore, using this fuel on current ships will necessitate engine modifications as well as the installation of new fuel tanks and safety equipment. In the year 2024, such engines are predicted to be commercially accessible. Another drawback is that ammonia is a toxic substance and combusted ammonia emits high amounts of nitrous oxide, also called laughing gas, which is a 300 times stronger greenhouse gas and depletes the ozone layer. Nitrous oxide is also an air pollutant and has detrimental health effects on people that live in the port area.


Methanol has several advantages. It is easier to store than hydrogen and upgrading a ship’s tank from traditional fuel oil to methanol is less expensive than installing LNG tanks. Furthermore, the storage of methanol on ships is easier and more economical. Methanol has less environmental impact than other shipping fuels because it dissolves well in water and only extremely high concentrations cause deadly circumstances or any change in local marine life. Methanol is abundant in the water, where it is created naturally by phytoplankton and rapidly absorbed by bacteria and microorganisms, allowing it to enter and maintain the food chain.

However, methanol also has drawbacks such as its low energy content meaning that methanol takes 2.54 times the storage space of conventional fuels for the same energy content, making it less appealing to smaller ships. Another problem is a required re-designing of ships in order to deploy methanol as ship fuel, such as bigger fuel tanks to allow for deep-sea voyages.


To fulfill the goals of the European Green Deal, it is essential to focus on promoting and employing low-carbon fossil fuels. There are, however, some problems with the e-fuels presented above.

Hydrogen is only a viable choice for short-distance ships and ferries. Both inland and maritime shipping might benefit from synthetic methanol and only ammonia can be used for deep-sea shipping. Regarding the potential for GHG emissions reduction, we need to bear in mind that these fuels can also be produced with fossil fuels, making them dirty fuels still. Hence, it is advised to only invest in fuels that are produced using renewable energy.

In the end, switching to these low-carbon fuels is not that simple because most of these fuels cannot be used for deep-sea shipping, only ammonia is a viable solution to this (for now). However, given its toxic potential, it is not seen as very interesting for companies to use. Moreover, a sudden switch to e-fuels is also unrealistic due to supply issues and because many of these fuels require re-designing ships which are costly for ship owners.

However, if the EU gives the right incentives and invests in making these fuels more commercially viable, it is doable. For this to be achieved, the EU should not focus on LNG that much in the FuelEU Maritime Proposal, but focus on investment in other fuels. Also, since LNG requires a re-designing of ships, it is better to focus on fuels with a higher GHG reduction potential. For the time being, the EU should give incentives to ship owners to reduce their operational emissions by reducing speed, for instance.


[1A sustainable green economy focuses on strategies in transport and energy etc. The blue economy focuses on marine sectors. Climate mitigation and adaptation techniques are included in both.

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