JAN-ERIK Räsänen has been on a personal journey that has led him to some new understandings about how to power both future and existing ships towards decarbonisation, he tells listeners to this podcast.

He is chief technology officer of the Finnish ship design and engineering company Foreship, which has been part of the consulting engineering inspection and certification group RINA since June 2025. Foreship’s specialism is the passengership sector, but his views are applicable to all ship types and to both newbuildings and existing ships.

Alongside all the alternative fuels now being developed, such as biofuels, e-fuels and even nuclear power, he ranks batteries as a significant technology to help fulfil global and regional decarbonisation goals.

It is a view that he attributes to a conversion experience, thanks to a chance meeting in 2011 with the CTO of a battery company during a ship inspection in Vancouver. At the time, he was sceptical that batteries were viable for ships. “My immediate thoughts were that this guy must be crazy,” he recalls. But that meeting was soon followed by a contract to explore whether two ferries could operate solely on batteries, which led to the largest battery retrofits ever done on ferries at that time.

With installed battery capacity across the global fleet now standing at about 1,900 MWh, he concedes that “my first impressions of batteries on board ships were completely wrong” and says in this podcast that he now has a mantra: “electrify what can be electrified”.

He provides details in the podcast of a number of battery-related passengership “firsts” with which Foreship has since been involved, including the largest battery conversion on a cruiseship and a ferry conversion that features both NMC (nickel, manganese, cobalt) and LFP (lithium-iron phosphate) batteries on board.

Installations such as these allow the generating engines to run at their optimal output, increasing efficiency compared with non-battery power plants, he says.

He acknowledges that a variety of solutions will be needed for all ship types and sizes to meet the emissions — and therefore efficiency — goals implied by the IMO and other regulations and ambitions, so he maintains what he calls an open-minded approach to technology choices.

For example, as well as his enthusiasm for batteries, he says in the podcast how alternative fuels can help align reality and requirements, but only if they are green fuels, such as bio-methanol, e-methanol or e-diesel. He is less keen on ammonia, especially for passengerships, because of safety concerns.

He also discusses LNG — which is a significant fuel in the passenger sector — but is concerned about its associated methane slip, especially at low loads, which brings him back to his core message: “the easiest way to reduce the methane slip from an engine is to install batteries” so that they can operate at their optimum load.