The quickest way is with methanol
Some shipping companies are already switching from heavy fuel oil to methanol. However, this is only sustainable on one condition. And whether there will be enough of the fuel is questionable.
Shipping is dependent on fossil fuels: Ocean-going vessels primarily refuel with heavy fuel oil. But the industry is set to become climate-neutral worldwide by the middle of the century. Hydrogen, ammonia or methanol are set to replace heavy fuel oil and other marine diesel. On behalf of Greenpeace the German Aerospace Centre (DLR) has now investigated which of the renewable fuels would be the quickest way to make the shipping fleet climate-neutral. The answer is clear: with green methanol.
Green means that the fuel is produced from renewable resources: from hydrogen, which is obtained by electrolysis, and from CO2. This can be captured directly from the atmosphere or come from other sources. If all ships in Germany were to use methanol as a fuel, the emissions of the fleet would fall by 96 per cent, according to the study.
But why methanol and not ammonia or hydrogen? Methanol is liquid at room temperature and can therefore be transported and stored in existing plants in a similar way to diesel fuel. The technologies for its production are tried and tested, and engines can also be converted. In addition to being easy to handle, methanol is less toxic than ammonia. However, the fuel is still flammable and toxic, but there are already regulations for handling methanol in the shipping industry.
One tank of methanol also goes further. At 4.4 kilowatt hours per litre, its energy density is higher than that of hydrogen and ammonia. On the other hand, it only achieves half the value of heavy fuel oil or marine diesel. A ship powered by methanol would need correspondingly larger tanks, or it would have to be refuelled more frequently.
Nevertheless, methanol remains the most attractive option and interest in the fuel is growing accordingly. Large shipping companies such as the Danish Maersk Group are already converting parts of their container fleet to methanol propulsion.
However, as interest in the fuel grows, so too does demand and uncertainty as to whether there will even be enough available in the future. Today, it is still hardly produced in a climate-neutral way. According to the study, however, the future annual demand is 5.7 million tonnes to supply the German shipping fleet alone.
The widespread use of green methanol in shipping would be expensive: it would require electrolysers and CO2 capture would also be costly. Without government incentives and regulatory pressure, there will be a lack of the necessary production facilities, according to the study. In addition, parts of German demand would have to be imported. Nevertheless, the DLR expects methanol to become established for certain types of ships or routes in the future.
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