FORESHIP SEES FUEL CELLS AND BATTERIES IN FUTURE MIX

Foreship is currently active in two cruise ship projects which use Foreship’s plug-and-play containerised ‘e-house’ solution as a means of integrating the fuel cell on board ship. Jan-Erik Räsänen, Chief Technology Officer at Foreship, discusses the future of cruise ship electrification with The Motorship

Why would the cruise industry consider batteries and fuel cells?

The IMO’s aim to halve marine greenhouse gas emissions by 2050 when compared to 2008 levels looks beyond the reach of even the most energy-efficient combustion engines. Supplementary or replacement shippropulsion technologies are therefore required, and battery systems alone are not capable of propelling large vessels over long distances. Against this background, fuel cell technology, which converts hydrogen-rich fuel into electrical and thermal energy by electrochemical oxidation, represents a promising alternative, especially if supported by battery systems for peak loads.

For vessels that are already diesel electric, like many cruise ships, what would be the trajectory to further electrification?

Conventionally, where big ships are concerned, the assumption has been that battery power is most useful for specific purposes, for example for manoeuvring in zero emissions zones. However, the reality is that battery power is increasingly being chosen for the way stored energy supports peak engine loading, improving flexibility and meaning that a specific operation can be carried out with fewer gensets.

Foreship has undertaken 39 projects covering shipboard battery power. Its assessment is that hybrid solutions achieve efficiency gains across the ship’s entire power load of between 2.5% and 4.7%. The true potential depends on a variety of factors, including the specific ship’s characteristics, its operating profile, the power plant set up, its use of and access to shore power, etc.

In some cases, owners would have liked to include a battery but it hasn't been possible. Why would that be the case?

Considering that battery power of 1MW/h can weigh in at roughly 10,000kg of extra equipment, clearly there are examples where ships are already operating too close to their stability limits to accommodate the installation.

To recommend the right battery power, we need a firm idea of objectives, but also a detailed analysis of the available space on board, the impact on stability, existing systems, the piping and cabling requirements, etc. In fact, there’s a fivestep Foreship approach that extends from the feasibility study and concept design stage, through to detailed analysis, class requirements and project management – either at the yard or with the ship underway.

Will batteries always offer some value beyond what fuel cells can provide and so be part of longterm electrification, or are they likely to just be a bridging technology while other zero-emission power systems mature?

Battery power will offer value beyond what fuel cells can provide for two reasons:

First, fuel cells offer – and will continue to offer – slow responsiveness to load variations. Batteries will provide the load ramping capability fuel cells need to optimise efficiency. In general terms, our view is that optimal efficiency will be achieved when a battery offering 10-15% of the fuel cell’s power rating is included for load ramping.

Like fuel cells, many of the alternative fuels being put forward to solve shipping’s low carbon needs won’t be practical until 2035 at least. In contrast, battery technology is mature enough to help today and is being scaled up on a commercial basis in a way that will grow its contribution significantly before other solutions become reality. Today, the installed base of shipboard battery power is equivalent to 560MW/h. As soon as 2025, we think this will reach 1GW/h.

Are fuel cells likely to move beyond the role of being a genset replacement?

We expect fuel cells will be used in a wider role than genset replacement in the years ahead. Shore power is not always available at the destinations cruise ships call, for example: we expect marine fuel cell technology to scale up to support zero emission hotel power - depending on the hotel load demand - to between 7MW to 13MW within five years.

Furthermore, where commercial ships are concerned, the market is fully aware of the progress being made by methanol as a fuel for two stroke engines. However, the situation is different for the four stroke engines which drive diesel electric cruise ships, where higher pressures and the balance between pilot and main fuels are real issues. There is no doubt that these will be solved by the engine makers, but there is a window of opportunity for fuel cells as a cruise ship propulsion technology. A fuel cell which used reformed LNG as its feedstock, for example, could do so without being subject to methane slip.