The Future of Hydrogen in Cargo Ships: Fuel Cells vs. Combustion Engines

As the world seeks alternative forms of clean energy, the use of hydrogen in cargo ships has gained significant attention. Would cargo ships opt for hydrogen fuel cells or combustion engines? This article explores the possibilities and the factors influencing such a decision.

Current Technological Landscape

The initial answer might seem straightforward: hydrogen fuel cells. However, the practical application in cargo ships is not as clear-cut. While fuel cells offer a cleaner and more efficient alternative, conventional internal combustion engines (ICEs) have shown impressive efficiency rates, particularly in large cargo vessels. An internal combustion engine in a cargo ship can achieve efficiencies over 50%, whereas fuel cells, although more efficient, come with high costs and the need for extremely pure hydrogen.

Cost and Efficiency Considerations

The cost of implementing hydrogen fuel cells is a major barrier. Not only are these systems expensive, but they also require incredibly clean and pure hydrogen to function optimally. This purity requirement makes internal combustion engines a more practical solution for many shipping companies. As a result, combustion engines might remain the preferred option until the cost of fuel cell technology comes down sufficiently.

Hydrogen Blending and Ammonia Alternatives

However, there is another pathway to consider. Hydrogen can be blended with the intake air of diesel engines to enhance combustion efficiency. Additionally, the by-products of hydrogen boil-off from liquid hydrogen can be used directly as fuel in these engines, leading to efficient utilization of resources and no waste. Companies like those behind the liquid hydrogen tanker "Suiso Frontier," which has recently completed a successful trial by delivering liquid hydrogen to Japan, are exploring these innovative solutions.

Alternative Hydrogen Carriers: Ammonia

A more stable and efficient alternative to hydrogen gas is ammonia. Ammonia can carry hydrogen energy with greater stability and efficiency. The technology for ammonia as a fuel has been around since the 1930s. For instance, ammonia-fueled buses were used in Belgium for a period. Despite the initial cost of ammonia being high, it has the potential to become a more viable option as technology improves and costs decrease.

Environmental Considerations

Ammonia-fueled vehicles, like their diesel counterparts, could face issues with nitrogen oxides (NOx) emissions. However, this is a non-issue. Both diesel and ammonia-powered vehicles can mitigate NOx emissions through the use of additives like Adblue, which neutralizes NOx gases, converting them into harmless nitrogen.

Conclusion

The choice between hydrogen fuel cells and combustion engines for cargo ships depends on several factors, including cost, efficiency, and the availability of clean and pure hydrogen. While fuel cells offer an environmentally friendly solution, internal combustion engines may remain the more practical option for the time being. The emergence of stable hydrogen carriers like ammonia holds promise for the future, but it will require further technological advancements to be economically viable.

As the technology evolves and costs decrease, we can expect to see a shift towards more sustainable solutions in the shipping industry. However, for the near future, a blended approach combining hydrogen with traditional engines and exploring ammonia as a viable energy carrier may offer the best path forward.