How international shipping has considerable potential for becoming more climate-friendly. A technical article ay Rainer Moritz and Lars Ronge.

The shipping industry is reducing CO2 emissions through various approaches to lessen its environmental footprint and to meet international climate goals. Key strategies here include efficiency improvements in design and construction, the use of alternative drives (such as fuel cells), the integration of renewable energy, operational measures, increased international regulation, harmonisation, and research collaboration.

Combining the various approaches can significantly reduce the industry's CO2 emissions. The fuel cell is therefore one of several technologies that will become increasingly relevant for the shipping industry to achieve the net-zero goal.

Using fuel cells as a means of propulsion in ships is still largely limited to pilot projects like those in inland shipping (see Figure 1). However, the first luxury yacht manufacturers are also using fuel cell propulsion. PEM (proton exchange membrane) fuel cells with a total output of almost 1 MW are used here. The Central Commission for the Navigation of the Rhine and its member states have agreed to largely eliminate greenhouse gases and other pollutants by 2050. This promotes research and development of greenhouse-gas-neutral technologies.

A question of technology

Various fuel cell technologies are available that can use natural gas or methanol as fuel in addition to hydrogen. However, hydrogen is the most commonly used fuel today due to its high energy density and clean combustion without emitting CO2 or other greenhouse gases. PEM fuel cell technology has become established for mobile applications even though every fuel cell technology has its specific advantages and disadvantages.

In maritime shipping, which usually has longer distances and deploys larger ships, solid oxide fuel cells (SOFC) are also used. The DLR Institute for Maritime Energy Systems is using the HELENUS research project to test a TRL-7 500 kW SOFC on an MSC World Europe-class cruise ship (see Figure 2) to generate both current and heat, which leads to a reduction in the use of conventional fuel.

One recurring question is about the origin of the hydrogen. Green hydrogen is needed for completely carbon-neutral operation. In other words, this is hydrogen that is produced from renewable energy. The majority of hydrogen used today is not yet produced in a climate-neutral manner. In this context, it quickly becomes clear that the transformation of our energy industry must be interlinked in numerous places and that holistic modeling is needed. Another question being discussed is the ideal form of hydrogen transportation. For example, it can be transported very efficiently in its bound form as methanol. Before use in the fuel cell, methanol must first be converted back into hydrogen (abbreviated to M2H2). This process can be climate-neutral if the methanol was produced using renewable energy.

Measurement and control technology for the fuel cell

The fuel cell as well as the necessary measurement and control technology for it are already available and fully developed. Fuel cell technology itself can be considered fully developed, although further research and development initiatives are expected to lead to improvements and technological advances. Figure 3 shows a simplified diagram of a fuel cell's function principle. Hydrogen reacts with oxygen from the ambient air to form water. This chemical reaction creates electrical voltage in the fuel cell, which can be utilised as current. A cooling circuit dissipates the heat generated by the chemical reaction.

JUMO products can help with monitoring, controlling, and evaluating the input as well as output variables. Typical measurands required for the fuel cell and its peripherals are pressure, temperature, and level. Many JUMO products are certified specifically for maritime use. For example, the JUMO MIDAS S07 MA pressure transmitter (see Figure 4) can be used to monitor the pressure of the hydrogen circuit.

As a system and solution provider, JUMO is represented at almost all levels of the automation pyramid (see Figure 5) with products, services, systems, and solutions.

The sails have been hoisted

Shipping is responsible for about 3 to 4% of human-induced CO2 equivalents worldwide. At the same time, CO2 emissions per transported metric ton are significantly lower compared to road and air transport. Only a rail-based system can achieve an even better ecological balance here. The International Maritime Organization (IMO) has taken several measures to reduce CO2 emissions by 40% by 2030 and 70% by 2050 compared to 2008.

International shipping has considerable potential for becoming more climate-friendly. Assuming that rail and ship will grow more strongly than road and air traffic due to their lower CO2 emissions, these cost savings will be even more significant. Fuel cell technology will find its place between purely battery-electric drives and synthetic fuels. The application is what counts. This is how we make the future green!