Renewable-Powered Battery Swaps: Unlocking Ship Electrification At Global Canals

Last Updated on: 7th July 2025, 10:24 am

The Maersk McKinney Moller Institute published an analysis in late 2024 exploring the potential for battery-electric shipping. Their study rightly concluded that battery-powered ships are not only viable but increasingly competitive, driven by falling battery prices, rising energy density, and straightforward integration of battery containers onto vessels. They missed on amplitude however, as they were using already outdated battery prices, as I pointed out with a reassessment of their break evens recently given $51  per kWh grid battery packs in China vs the $300 per kWh the Institute had used.

As frequently happens when I publish on electrified shipping, a commenter chimed in with the thought of mid-ocean recharging of ships. The comment has occurred sufficiently often that I thought it worth publishing a clear analysis of why this isn’t going to happen so that I could use it as a response in the future. That doesn’t mean that there isn’t merit in mid-journey electron bunkering, just that it won’t be happening in mid-Atlantic or in the Aleutians.

The underlying notion behind mid-ocean charging is straightforward. Ships traveling thousands of kilometers across oceans could theoretically reduce onboard battery storage if intermediate charging facilities existed. Advocates suggest that just ten or twenty strategically placed offshore stations worldwide could suffice, enabling vessels to recharge en route rather than carry excessively large battery packs. Offshore wind farms with battery buffer storage could provide the electricity, offering an elegant technical solution to maritime emissions. Conceptually, this approach appears compelling, particularly given abundant renewable resources in certain remote oceanic regions.

Yet practicality in ocean infrastructure consistently faces harsh economic realities. Offshore facilities invariably cost more than their terrestrial counterparts. A useful rule-of-thumb in marine engineering suggests that infrastructure costing a notional $1 onshore escalates to roughly $10 offshore, about $100 subsea, and potentially $1000 or more when placed on deep seabeds. This exponential escalation in costs does not solely reflect complexity in engineering but accounts for increased risk, construction difficulty, maintenance challenges, and remote operational logistics.

Even offshore oil and gas, an industry accustomed to colossal capital expenditures, developed only in response to decades-long offshore reserves and high global oil prices. Renewable energy infrastructure typically follows a similar economic logic. Offshore wind platforms, for instance, become economically viable due to their high capacity factors, proximity to dense electricity demand areas, and limited available land-based alternatives.

Offshore HVDC platforms are being built because offshore wind is so valuable as a 50%+ capacity factor resource relatively close to major demand centers. Even there, as part of the TenneT 2050 scenario planning we cut 20 GW of the most expensive offshore wind, which was only 200 km from shore, because we economized by among other things reducing the not-going-to-happen hydrogen economy electrolysis in the base scenario by tens of GW of capacity.

Applying these financial and operational lessons to mid-ocean recharging stations highlights substantial barriers. Take, for instance, the suggestion that ships traveling trans-Pacific routes from China to North America might recharge near the Aleutian Islands. On a map, the Aleutians appear conveniently positioned along great-circle routes between major Asian ports and U.S. west coast destinations. However, geography alone does not determine practicality. The Aleutians rank among the planet’s most inhospitable environments. The islands regularly experience severe weather events, including hurricane-force winds, frequent dense fog, freezing rain, and violent seas. Steep volcanic terrain further complicates any large-scale construction projects, while seismic activity introduces significant risk to infrastructure longevity.

That there are old military bases on the Aleutians is due to the deep geopolitical security concerns of the Cold War with the USSR, not because it’s a welcome gig for soldiers. I’m pretty sure that anyone assigned there was either being punished, or was very ambitious and volunteered in order to jump ranks quickly. Eareckson Air Station on Shemya Island, which deals with radar surveillance and occasional help for trans-Atlantic flights, located near the western end of the Aleutians, is the only U.S. military facility still in operation and it has a very small staff of rotating military and contractor resources.

Any attempt to establish large renewable energy generation facilities or battery storage in such harsh conditions faces numerous logistical hurdles. These islands lack existing heavy infrastructure, local supply chains, or even basic transportation networks. Workforce management alone presents severe obstacles. The remote location, dangerous working environment, and lack of local housing would significantly increase operational complexity and cost.

Convincing shipping operators to pause at these remote, risky mid-route points compounds these problems. Operators focus primarily on reliability, efficiency, and predictable scheduling. Stopping at a facility located in a forbidding environment runs counter to these basic commercial priorities.

Proponents might suggest other remote oceanic locations for intermediate charging stations, such as mid-Atlantic floating facilities. Yet similar practical considerations apply. The Atlantic, while narrower than the Pacific, remains storm-prone, with consistently challenging wave conditions. Building and maintaining platforms in deep waters of the North Atlantic would again introduce exceptional costs and complexity, far exceeding comparable land-based renewable alternatives or biofuel-driven propulsion methods.

Despite these significant challenges, the broader concept of intermediate charging or battery replacement should not be dismissed entirely. Practical and economically attractive solutions exist where ships already routinely pause: maritime choke points. Specifically, battery exchange systems could leverage existing infrastructure at the Suez Canal, Panama Canal, and Strait of Malacca. Possibly the Strait of Gibraltar as well. Containerized batteries stored dockside could be quickly swapped as vessels await canal transit or passage through crowded straits. This approach drastically reduces infrastructure costs and complexity, aligning smoothly with existing maritime procedures and schedules.

Wind and solar resource availability varies significantly among the key maritime chokepoints under consideration. Near the Suez Canal, solar resources are abundant due to Egypt’s favorable climate, offering consistent solar irradiance levels conducive to large-scale photovoltaic installations. Wind potential is also considerable in certain coastal regions near the canal, making renewable-powered battery exchanges highly feasible. The Panama Canal similarly enjoys strong solar potential year-round, supported by high annual solar irradiance typical of Central America. Wind resources there are more moderate but sufficient in coastal and offshore zones for complementary generation.

The Strait of Malacca has good solar availability due to its equatorial location, providing consistent daily solar generation potential, although wind resources in this region are comparatively limited due to less predictable and weaker winds. The Strait of Gibraltar offers substantial wind resources, notably in the Tarifa region, which is already home to established wind farms. Coupled with good solar irradiance, particularly in southern Spain and Morocco, Gibraltar also emerges as a practical candidate for renewables-driven battery exchange infrastructure.

Containerized battery exchange stations would require minimal modifications to current shipping operations. Existing port cranes, supply chains, and logistics infrastructure can readily accommodate standardized battery containers. Crucially, these exchanges could occur rapidly, minimizing disruptions to ship operations. While limited to a small number of global choke points, this approach still provides significant potential for reducing onboard battery capacity, cutting vessel weight, and improving shipping economics.

Standardization across the industry remains essential to realizing this potential fully. A global standard for battery container dimensions, connection interfaces, electrical specifications, and logistics procedures would significantly enhance adoption rates and scalability. Regulatory incentives or mandates, potentially driven by the International Maritime Organization (IMO) or key national maritime regulators, could accelerate widespread adoption.

Battery technology advancements further reinforce the practicality of choke point containerized exchanges. Battery costs continue to decline rapidly, approaching thresholds at which electric propulsion economically outcompetes fossil-based marine fuels on shorter and mid-length routes. Improvements in battery energy density, reduced thermal management complexity, and increased cycle life directly support containerization logistics. Simpler packaging, lower fire risk, and improved efficiency also translate directly into lower operational and insurance costs.

The maritime sector can learn important lessons from analogous industries. Offshore wind developers continually refine approaches to reduce offshore operations and favor near-shore solutions. Oil and gas producers have long recognized the extreme cost premium attached to deep-water platforms and subsea installations, which only proved viable with sustained high commodity prices. HVDC platforms in renewable transmission similarly face relentless pressure to economize by minimizing offshore infrastructure complexity and cost.

Integrating these industry experiences highlights a clear and rational pathway forward for battery-powered shipping. Rather than chasing costly and logistically challenging mid-ocean charging stations, maritime electrification advocates should prioritize practical, economically realistic containerized battery exchanges at established global chokepoints. This approach maximizes existing port infrastructure, minimizes investment risk, and leverages proven technology standards. It aligns neatly with current ship operations, ensures scalability, and significantly improves maritime decarbonization economics.

Moving forward, maritime stakeholders, including ship operators, port authorities, regulators, investors, and equipment suppliers, should collaborate closely to define battery exchange standards and infrastructure investments at key locations. Early pilot projects at locations such as the Suez or Panama canals could demonstrate feasibility, economic attractiveness, and operational efficiency. Success in these pilot projects would then justify broader rollout, supported by regulatory frameworks that incentivize or mandate cleaner maritime propulsion systems.

Ultimately, containerized battery exchanges at maritime choke points represent the most logical, economically sound, and practically feasible strategy for rapidly advancing ship electrification. While the vision of mid-ocean charging stations captures imagination, economics and practicality consistently guide us toward shore-based solutions that deliver clear benefits without extraordinary risk or excessive cost.