The maritime industry severely underestimates how quickly the numbers are coming down for space, weight and cost of batteries and electric engines, according to a study by engineers and economists.

Directly electrified shipping will soon outgrow the limitations of current short-haul trial projects — and even more quickly if governments force the industry to internalise the environmental and health cost of carbon emissions.

The study by the Lawrence Berkeley National Laboratory appeared in the monthly journal Nature Energy under the title “Rapid battery cost declines accelerate the prospects of all-electric interregional container shipping”.

“Past studies on ship electrification have relied on outdated assumptions on battery cost, energy density values and available onboard space,” wrote California-based Jessica Kersey and co-authors Natalie Popovich and Amol Phadke.

Warned off of batteries, shipowners have been investing in low-tech “short-term measures” to reduce carbon emissions, such as slow steaming, route optimisation and hull fouling management.

“However, the 10% to 15% emissions reductions achievable through these measures are not sufficient to comply with forthcoming International Maritime Organization efficiency regulations,” the researchers wrote.

To get beyond that marginal level of decarbonisation, direct electrification is a better answer than green fuels such as hydrogen and ammonia, they believe, not least because of expected inefficiencies in the fuel production process.

Battery power is increasingly playing a supplementary role in long-haul routes already, but fully electrified shipping is so far limited in practice to ferries and other shuttle routes between fixed points.

The researchers pointed to short-range projects such as the 120-teu experimental autonomous shuttle container vessel Yara Birkeland (built 2020), but said shipping must raise its expectations.

“With the exception of these initial pilot projects, battery-electric propulsion has been underexplored as a potential low-emissions alternative in the marine shipping sector, despite its considerable emissions reduction potential, recent decline in battery costs, improvements in battery energy densities, increasing availability of low-cost, renewably generated electricity, and its substantial efficiency advantage over e-fuels such as green hydrogen and ammonia,” they wrote.

Maersk studies

The authors acknowledge that mainline shipping companies including AP Moller-Maersk have looked into the outlook for long-haul battery-powered shipping and found it wanting.

Maersk said last year that, based on studies and experience with batteries on its own ships, its focus would be on new fuel types instead. A spokesman told TradeWinds that to attain full battery-powered propulsion, an unfeasible 80% of cargo capacity on the largest ships on a Singapore to Rotterdam route would have to be devoted to containerised batteries.

But the new study challenges this view.

It compared current battery power, size, and cost with the projected values for 2030 on eight size classes of container ships from 1,000 teu to 18,000 teu, trading on 13 global routes.

The 13,100-teu container ship Maersk Evora (built 2011). The new study challenges the current position of shipping giants such as Maersk. Photo: Port of Los Angeles

“Our results suggest that over 40% of global container ship traffic could be electrified cost-effectively with current technology, reducing CO2 emissions by 14% for US-based vessels,” they wrote.

The researchers have done the numbers on efficiency losses from the weight and volume of batteries, and Maersk’s 80% figure for the cargo space that batteries would displace on the biggest long-haul ships is not transferable to medium-sized tonnage.

“For a small neo-panamax container ship, representing an average container ship in the global fleet, the volume required by the battery system is less than the volume currently dedicated to the [engine] and fuel tanks for routes under 3,000 km [1,860 miles],” they wrote, referring to ships of around 7,650 teu.

For container trades, weight is less economically significant than volume, but still a concern. Batteries would add about one metre to the draught on a 7,650-teu container ship operating on ranges under 5,000 km. The batteries needed for ranges longer than that, however, could exceed its maximum draught.

The falling cost of the batteries themselves remains the most important number. Adjusting for the costs associated with volume and space, the researchers arrive at results that make short-range fully electrified shipping economically feasible.

“[At] battery prices of $100 [per] kWh, the electrification of intraregional trade routes of less than 1,500 km is economical, with minimal impact to ship carrying capacity,” they wrote.

The economically feasible range for battery-powered container shipping leaps from 1,500 km to 5,000 km at that power price when the environmental costs of fossil fuel shipping are factored in — especially if governments can internalise those costs through regulatory action.

If new battery technology achieves a $50 per kWh price point, the economical range nearly doubles.