Shipping accounts for a significant amount of world CO2 emissions because to global trade, cruises, and fisheries. 90 percent of all commodities are transported by water.
As a result, the fight against climate disasters must begin there as well. The bulk of ocean, coastal, and inland vessels still run on heavy fuel oil and diesel, with many of them running without any sort of exhaust gas treatment.
Currently, shipping accounts for around 2.5 percent of global greenhouse gas emissions. However, unlike vehicles, huge ship engines are rarely replaced with electric motors. Hydrogen, methanol, and ammonia are now considered to be climate-friendly replacement fuels.
Ammonia is a highly toxic gas. Its large-scale manufacturing utilizing nitrogen from the air and hydrogen is already well advanced, and it is an essential raw material for fertilizer manufacture. One nitrogen atom and three hydrogen atoms make up the chemical molecule, and hydrogen is a climate-neutral fuel.
Pure hydrogen, on the other hand, has the disadvantage of requiring a lot of storage space or requiring a lot of energy to decrease. The gas is either liquefied at minus 253 degrees Celsius or held at 700 bar, or 700 times the atmospheric pressure. According to Gunther Kolb of the Fraunhofer Institute for Microtechnology and Microsystems, “as a liquid, ammonia is satisfied with a modest minus 33 degrees Celsius at normal pressure and 20 degrees Celsius at 9 bar.” Storage and transportation are less complicated. Ammonia, on the other hand, makes hydrogen storage easier.
However, because of the single nitrogen atom, ammonia may generate laughing gas, a potent greenhouse gas, if it is not entirely burnt. Because current ammonia engines do not exist, the amount of nitrous oxide released during their operation is unknown.
Engineers like Bastian Lehrheuer of RWTH Aachen University’s Fuel Science Center are certain that the problem can be solved with an exhaust gas aftertreatment system. MAN, one of the world’s major marine engine manufacturers, is conducting extensive research on ammonia technology. Wärtsilä, a German-Finnish company, has also launched a demonstration project.
Lehrheuer believes that engines that can run on two fuels, such as methanol and LPG (Liquefied Petroleum Gas), may readily be modified to run on ammonia. Ammonia, on the other hand, may be utilized not just in engines but also in fuel cells.
To accomplish so, the hydrogen is isolated from the ammonia and purified to a great extent. Pure nitrogen escapes into the atmosphere or is combined with hydrogen in the fuel cell. No climate-damaging nitrogen oxides, including nitrous oxide, are created if the process is carried out optimally.
The fuel cell, according to Michael Steffen of the Duisburg Center for Fuel Cell Technology, is a mature technology. Fuel cells and accompanying electric motors, on the other hand, are more difficult to adapt to the power requirements of huge ships. Nonetheless, “ammonia and fuel cell technologies may be deployed from yachts to ocean liners from a strictly technological standpoint.”
Martin Cames of the ko-Institut in Berlin, like Steffen, believes that ammonia as a ship fuel is first employed in internal combustion engines and afterwards in fuel cells. He proposes technological steps to maintain the environmental danger of ammonia as low as feasible as the first author of a research on the subject: Ammonia is just as toxic as heavy oil in terms of its lethal effect on marine life, such as in the event of an accident.
Cames maintains a close check on nitrous oxide emissions as well. “Ammonia is a potential for future maritime fuel since it is a carbon-free post-fossil fuel,” he concludes. It is projected to be less expensive than other non-fossil fuels. Its usage on passenger ships is debatable since tank leakage might harm passengers. Cames, like Bastian Lehrheuer, believes that methanol might be a viable replacement to ammonia since it is less harmful to the environment.
Larger tanks are required for both ammonia and methanol if the ships are to go as far as before with a single fuel load. Lehrheuer adds that the energy level of both compounds is only around half that of diesel.
Furthermore, ammonia is only environmentally good if it is generated in a carbon-neutral manner. The standard technique does not work in this way. 1.1 percent of worldwide greenhouse gas emissions are attributed to this industrial activity alone. As a result, several researchers are focusing on other methods of manufacturing ammonia. “How sustainably hydrogen is produced is the essential component for environmental friendliness,” explains Ralf Peters of Forschungszentrum Jülich. This will happen in the future in places where substantial amounts of electricity from solar and wind power are accessible, such as Australia and Chile.
There are also some early actual initiatives, such as the Campfire research project’s ammonia drives for a sports boat, a small inland ferry, and a cruise ship, or the retrofitting of a supply ship for a Norwegian energy firm.
