Two years ago, a pre-study by Lighthouse and the Swedish Transport Administration showed that it is possible to operate an electrified cargo vessel during the summer between Skellefteå and Södertälje. A follow-up study now shows that the concept of green, electrified shipping can also become economically viable in winter.

It is often said that electrified shipping is only suitable for shorter routes, primarily archipelago traffic. In Sweden, for example, the Helsingborg–Helsingør route is served by a fully battery-powered vessel, while longer routes such as Stena Line’s service between Gothenburg and Frederikshavn require a hybrid solution.

The distance between Skellefteå and Södertälje is ten times longer—900 kilometers (about 560 miles). Researchers were therefore quite surprised when, two years ago, they concluded that it is indeed fully possible to transport battery cells using green electricity by sea between Northvolt and Scania. At least during the summer. In winter, ice creates challenges. A new pre-study has therefore examined how a smaller cargo vessel (the concept vessel ELINORR), with capacity for 130–140 TEU containers, would perform in ice conditions. Is it environmentally and economically competitive? How great is the risk of delays?

“In a severe ice winter, there can be significant delays and an increase in greenhouse gas emissions. In a normal or mild winter, there are either no delays or only a few isolated occasions when you do not arrive on time,” says Martin Ericson Borgh, one of the authors of the pre-study Ice-going performance prediction and voyage planning of electric ships operated between Norrland and southern Sweden.

A substantial amount of battery capacity is required to operate ELINORR. In a mild winter, five battery containers are not enough to enable fully shore-powered operation on all voyages under ice-free conditions. At the same time, an alternative with fifteen containers provides no noticeable improvement compared with ten containers (approximately 35 MWh of battery capacity), which is what the study recommends installing on board.

“During a severe winter, Scania in Södertälje may also need to be prepared to build up an additional stock of battery cells before winter,” says Martin Ericson Borgh, and continues:

“When ice conditions along the route improve during a particular voyage, it is also possible to increase speed somewhat, from eight up to around twelve knots. That way, the schedule can be recovered fairly quickly. There is also some margin to load a few additional containers. A third option is to transport a few containers by truck.”

So how does ELINORR compare with land-based transport from a sustainability perspective? Quite well, actually. A comparative study—where fossil fuels were not even an option—showed that over time the vessel results in lower emissions than an intermodal transport setup combining rail and road.

“In a severe ice winter, it is doubtful whether ELINORR can deliver lower emissions than transport primarily by rail. However, ELINORR is always more sustainable than road transport.”
“A key prerequisite is that the size of the vessel is adapted appropriately. It must not be too large, and the load factor must be high for the voyage to be energy-efficient. ELINORR should be regarded more as a container feeder.”

A third prerequisite, of course, is Sweden’s large supply of green electricity. South of the Baltic Sea, it would likely not be economically feasible, according to Martin Ericson Borgh.

“The biggest challenge will probably be finding shipowners willing to invest in a vessel like this. At present, it would likely require having a contract with the transport buyer for five to ten years. At the same time, we believe interest may increase as new EU regulations are introduced—regulations that will also cover smaller vessels under 5,000 gross tons.”

The pre-study Ice-going performance prediction and voyage planning of electric ships operated between Norrland and southern Sweden was authored by Zhiyuan Li (Chalmers University of Technology) and Martin Ericson Borgh (RISE).