EXMAR report 2023

34 INNOVATIONS From grey to blue and green Ammonia produced by steam reforming of natural gas is currently labeled ‘grey’ ammonia. The production process has a certain CO 2 footprint, which now comes with a cost in certain regions of the world where CO 2 emission trading schemes are starting to be applied. To mitigate CO 2 emissions, the ammonia production plants using natural gas as feedstock are looking into capturing and storing the CO 2 generated during the production process. Ammonia manufactured in combination with CCS is labeled ‘blue’ ammonia. Lastly, to fully avoid the use of fossil fuels, several producers are looking into projects to shift back to the production of ammonia using electrolysis. When renewable electricity is used, the ammonia produced is labeled ‘green’ ammonia. Ammonia as energy carrier Worldwide production of ammonia in 2023 was around 180 million tons. Almost all of it is currently produced from fossil fuels. The largest share, over 70%, is used to produce fertilizers, which makes it a fundamental part of the global food supply chain. Other ammonia applications include urea for catalyzer technology, explosives for the mining industry, refrigerants, base chemicals for synthetic fabrics and base chemicals for plastics manufacturing. It is relatively easy to produce ammonia using renewable energy, so a new ammonia application is emerging: the use of ammonia to transport energy. The push to shift away from fossil fuels and towards renewable energy creates a demand for renewable energy transportation. Whether it is solar, wind or hydropower, most of the renewable energy captured today is transformed into electricity. Unfortunately, transporting electrons over very large distances is not possible with current technology. Renewable electricity needs to be transformed into molecules so it can be moved from one continent to another. Together with its partners in the Belgian Hydrogen Import coalition, EXMAR has investigated several potential molecules that could be used as energy carriers. Imports from various locations were considered using liquefied hydrogen, e-methane, e-methanol, e-ammonia and liquid organic hydrogen carrier (LOHC) as an energy carrier. The calculation model was updated in 2023; it continues to confirm that e-methane, e-methanol and e-ammonia are the more economical choices. However, e-methane and e-methanol have a distinct disadvantage as they also need CO 2 as a feedstock to combine with the green hydrogen, whereas e-ammonia needs only nitrogen, which can be captured cheaply from the air. Liquefied hydrogen remains uneconomical in large volumes and at large distances because of the high technology cost of transporting it at -253°C and its low volumetric energy density. EXMAR’s conclusion is that ‘green’ ammonia is a very suitable candidate as an energy carrier for renewable energy, although the cost is still relatively high and the technology needs to improve to make it more cost efficient. Ammonia as marine fuel Another new application is the use of ammonia as marine fuel. Due to the absence of carbon in the ammonia molecule, ammonia combustion in a ship’s engine does not produce any CO 2 . The only emissions from the stack of an ammonia fueled ship are water vapor and nitrogen, with some traces of NO X and N 2 O (the last of which is lower than the allowable emission limit). Clearly, the