The maritime shipping industry, responsible for nearly 90% of global trade by mass, heavily relies on HFO, resulting in substantial CO2, SO2, and NOx emissions. These emissions contribute significantly to climate change and air pollution, causing premature deaths. The International Maritime Organization (IMO) is implementing regulations to reduce GHG emissions, pushing the industry to adopt zero-emission alternatives. While electrofuels are considered, their high cost poses a challenge. This paper focuses on battery-electric propulsion, a largely unexplored alternative, despite its efficiency advantages and recent cost reductions in battery technology. Past studies often relied on outdated battery cost and energy density assumptions and treated onboard space as a fixed constraint. This research addresses these limitations by treating the space used for battery energy storage (BES) as an opportunity cost and examining the economic feasibility and environmental implications of battery-electric containerships across various ship sizes and trade routes.

Existing literature highlights the need for low-emission alternatives to HFO due to tightening regulations and the substantial environmental impact of the current system. Short-term solutions like slow steaming offer limited emission reductions. Hybrid battery technology provides some improvements but falls short of complete decarbonization. Other alternatives, including small modular nuclear reactors and various alternative fuels (marine gas oil, LPG, LNG, methanol, and biofuels) present challenges in terms of cost-competitiveness and lifecycle GHG emissions. Direct electrification is significantly more efficient than electrofuels but has been under-explored in maritime shipping due to past limitations in battery technology. This study builds upon previous work by incorporating up-to-date battery cost and energy density data and addressing the opportunity cost of using ship space for batteries.

The study uses a techno-economic model to assess the feasibility of battery-electric containerships. Two scenarios are defined: a baseline scenario using current best-available data and a near-future scenario projecting 2030 improvements. Eight containership size classes are modeled across 13 major world trade routes, creating 104 scenarios. The model calculates energy needs, CO2, NOx, and SOx emissions, and the total cost of propulsion (TCP). The volume used for the BES system is treated as an opportunity cost, representing forfeited cargo capacity. The model incorporates various cost factors, including battery costs, charging infrastructure costs, HFO costs, operating and maintenance costs, and environmental damage costs (NOx, SO2, and CO2). The Admiralty Law is used to approximate containership energy consumption. Equations are presented to calculate energy needs for both ICE and battery-electric ships, accounting for differences in engine efficiencies and mass, and the resulting changes in vessel draught. The study also considers various battery chemistries (LFP, NMC, NCA, LTO) and charging infrastructure requirements, including megawatt-scale charging and offshore charging possibilities. The levelized cost of charging infrastructure is estimated, and environmental impacts are assessed by comparing emissions intensities of battery-electric vessels with HFO/VLSFO-fueled vessels across different grid emission intensities.

The analysis reveals that for battery prices of US$100 kWh⁻¹, battery-electric containerships are cost-effective for routes under 1,000 km (without considering environmental damages) and up to 5,000 km when environmental costs are included. A reduction in battery price to US$50 kWh⁻¹ extends the cost-effective range significantly. The study shows that minimal carrying capacity needs to be sacrificed for battery systems on shorter routes. For longer voyages, larger ships show proportionally smaller reductions in carrying capacity. The required charging infrastructure (up to 300 MW) is achievable with current technology. The levelized cost of a 300 MW charging station is estimated to be US$0.03 kWh⁻¹ at 50% utilization. The near-future scenario projects a significant increase in the cost-effective range due to lower battery costs and higher energy density. However, for voyages over 5,000-6,500 km, the weight of batteries leads to draughts exceeding safe operating parameters. While containerships are the focus, the study suggests potential for electrification of other ship types like bulk carriers and tankers, with weight limitations being a key factor for those vessels. The study projects that about 40% of global container shipping traffic could be cost-effectively electrified, resulting in substantial reductions in CO2, NOx, and SOx emissions, particularly in regions with cleaner electricity grids. Figures in the paper illustrate the TCP analysis under baseline and near-future scenarios, highlighting the impact of battery costs, energy density, and charging infrastructure on economic feasibility.

The findings demonstrate that battery-electric shipping offers a viable pathway to decarbonize the maritime sector, particularly for shorter routes. The economic viability is strongly linked to battery costs, with lower prices significantly increasing the cost-effective range. The incorporation of environmental costs reinforces the economic advantage of electrification. The study highlights the importance of strategic adjustments to container shipping logistics and the potential for intermediate recharging to further expand the range of battery-electric vessels. The higher efficiency of direct electrification compared to e-fuels provides a strong argument for prioritizing this technology. While challenges remain regarding the cost of batteries and charging infrastructure, the ongoing development of battery technologies and the potential for innovative financing mechanisms could accelerate the transition. The integration of renewable energy sources with charging infrastructure is crucial to maximizing emissions reductions.

This study provides strong evidence that rapidly improving battery technology makes direct electrification a viable pathway for decarbonizing a substantial portion of the shipping industry. Cost-effective electrification is achievable for a significant portion of global container shipping traffic with current technology, with further improvements projected for the near future. Future research should explore intermediate recharging strategies to make longer-range voyages feasible, investigate the potential for electrification in other ship types, and examine innovative financing models to support the transition.

The model relies on certain assumptions, including projected battery cost and energy density improvements, charging infrastructure utilization rates, and environmental damage costs. Variations in these assumptions could affect the results. The study focuses primarily on containerships and may not fully capture the complexities of electrifying other ship types. The model uses a simplified energy consumption estimation, neglecting additional energy needs for manoeuvring and hoteling, and variations in energy savings due to slow steaming practices. The exclusion of battery production emissions, due to the wide variation in existing estimates, is another limitation.