Could Battery-Powered Container Ships Serve Transatlantic Trade?

Prospects for Battery-Electric Container Ships across the North Atlantic

Many years ago, University of Michigan Professor of Business C. K. Prahalad authored Competing for the Future, in which he explored a concept termed the “convergence of technologies.” A convergence of technologies involving advances in the design of container ships and advances in battery technology offers the prospect of a large battery-electric container ship actually sailing between the ports of Algeciras and Halifax, across the North Atlantic.

Introduction

The advent of lower cost solar and wind electric power has prompted development of energy storage technologies, including low-cost, grid-scale energy storage batteries. While some grid-scale energy storage systems are non-mobile, it is actually possible to adapt other grid-scale storage technologies for mobile operation in mega-scale transportation vehicles, such as ships. The size of container ships has increased over the past 40 years, with the largest ships offering up to 24 times the capacity of the smallest container ships.

Researchers involved in energy storage development have focused on long-life, low-cost technology that would be recyclable. Combining advances in low-cost electro-chemical energy storage with advances in container ship development offers the prospect of a battery-powered container ship that could sail across the North Atlantic Ocean, with the shortest route connecting the Western Mediterranean transshipment terminal at Algericas with the port of Halifax in Eastern Canada, a distance of 3,300 nautical miles. Recent developments in game-changing container transfer and vertical container stacking technologies promise to enhance future container transshipment at the Port of Halifax, connecting to Boston and Montreal.

Slow sailing

While container ships can sail at maximum speeds of between 22 and 26 knots, some operators save fuel and pass on savings to customers by sailing at half that speed. That precedent indicates a market segment for a lower-speed service. Development is underway to introduce a new generation, wind-powered freight ship on the North Atlantic service, serving a segment of the market that seeks to reduce supply chain carbon emissions. The advent of low-speed sailing and the expected introduction of wind-powered ships to the North Atlantic service suggests a market for battery powered container ships.

A container ship of 12,000 TEU capacity with a beam of 158 feet and a length of about 1,100 feet may be used as a basis for a trans-Atlantic battery powered ship. The diesel engine of 60,000 horsepower and fuel tanks will be removed and replaced by 720 forty-foot containers carrying batteries, divided into two levels of 360 containers each. Each container would hold 4,000kWh of battery power, giving a possible 2,880,000 kWh of stored energy. Sailing at 11 knots would require 1/8 the power of sailing at 22 knots, or about 7,500 horsepower.

At 11 knots, the ship could sail for 480 hours and cover over 5,000 nm carrying 10,000 TEU. It could depart from any of Algeciras, Tangier or Rotterdam and stop at Halifax for partial recharge of the batteries and transshipment of containers, then sail onwards to Newark. A larger, Triple-E class container ship with 880 containers of battery packs could carry 16,000 TEU on the same route at a speed of 13 knots.  

Recharge stations

The Azores are located 1,200 nm from Algeciras and 1,500 nm from Rotterdam and represent a convenient location to partially recharge “plug-in” trans-North Atlantic battery powered ships. A partial recharge at the Azores would allow large battery-powered ships to sail between Western Europe and U.S. East Coast ports such as Jacksonville, Charleston, Norfolk and Newport News. It would also allow a smaller battery-electric ship to sail between Western Europe and the Port of Quebec City. Possible energy sources could include advanced nuclear technology, floating wind power with land-based energy storage, floating energy storage or charged liquid electrolyte (for vanadium flow batteries).

Battery-electric ships sailing between Western European ports and America southern east coast ports such as Savannah, Jacksonville and Charleston as well as New Orleans would  also benefit from the development of a recharge station at Bermuda. A recharge station at Bermuda would allow battery-ships from Europe to sail to the Panama Canal, where an additional recharge station may be possible to allow the ships to sail to north to Los Angeles and south to Lima and Santiago.

Competitive mobile energy storage

There are three main competitors capable of supplying mobile renewable energy storage technology suitable for ship propulsion. AMBRI of Boston offers a liquid metal battery technology that can withstand over 20,000-deep cycle discharges. A forty-foot container of their batteries can offer 4,000kWh of energy storage and requires recharging during layovers at port. Vanadium Corp. Resources offers a liquid electrolyte flow battery technology, where negative and positive electrolytes are carried in separate insulated tanks. To generate electric power, pumps flow liquid electrolyte through cell stacks, with tanks offering 40 watt-hours per liter of energy storage (with expectations that power density will to increase to over 60 wh/l). During layover at port and at recharge stations, pumps could exchange discharged electrolyte for recharged electrolyte, with massive volumes of discharged electrolyte being recharged at ports and at recharge stations.

A Vanadium redox flow battery located at the University of New South Wales (Radiotrefoil / CC BY SA 4.0)

Combined wind and battery power

Recent advances have occurred in mobile wind power technology, including airborne or flying sails, rotating cylindrical Flettner rotors, extendible height airfoil sails and even deck-mounted wind turbines. There would be scope to combine some wind power technologies with battery-electric ship propulsion. On eastbound voyages from North America to Europe, airborne sail-kites would assist electrical propulsion to increase sailing speed while conserving battery energy. Depending on wind speed on eastbound voyages, either an airborne or a deck-mounted wind turbine could help recharge batteries while at sea.

The angle difference between wind direction and sailing direction, along with the difference between sailing speed and wind speed, would determine whether to deploy technology like Flettner rotors or deck-mounted airfoil-sails to assist in ship propulsion. Such assistance would reduce drain on batteries and reduce the time duration at electrical recharge stations.

Conclusions

The convergence of contemporary maritime and mobile energy storage technologies provides the basis by which to explore the possibility of trans-Atlantic battery-powered ship propulsion. While technically possible and theoretically capable of sailing extended distances, many maritime economists would question the feasibility of battery-powered container ships connecting Western Europe to North and South America across the Atlantic Ocean. Conversely, environmental advocates would argue for the introduction of such ship technology to the international trade routes. While converting a container ship to plug-in battery power would reduce overall payload capacity, it could carry sufficient payload to be viable.