Home Top News Rapid battery cost declines accelerate the prospects of all-electric interregional container shipping

# Rapid battery cost declines accelerate the prospects of all-electric interregional container shipping

International maritime shipping—powered by heavy fuel oil—is a major contributor to global CO2, SO2, and NOx emissions. The direct electrification of maritime vessels has been underexplored as a low-emission option despite its considerable efficiency advantage over electrofuels. Past studies on ship electrification have relied on outdated assumptions on battery cost, energy density values and available on-board space. We show that at battery prices of US$100 kWh−1 the electrification of intraregional trade routes of less than 1,500 km is economical, with minimal impact to ship carrying capacity. Including the environmental costs increases the economical range to 5,000 km. If batteries achieve a US$50 kWh−1 price point, the economical range nearly doubles. We describe a pathway for the battery electrification of containerships within this decade that electrifies over 40% of global containership traffic, reduces CO2 emissions by 14% for US-based vessels, and mitigates the health impacts of air pollution on coastal communities.

## Main

Transporting 11 billion tonnes annually, the maritime shipping industry handles nearly 90% of global trade by mass1,2. The industry’s meteoric growth has been underpinned by access to cheap, energy-dense heavy fuel oil (HFO). The shipping industry consumes 3.5 million barrels of low-grade HFO annually, produces 2.5% of total anthropogenic carbon dioxide equivalent (CO2e) emissions in 20182,3, and engenders enormous damages from marine eutrophication and ecotoxicity, air pollution, and climate change impacts4. By 2050, maritime shipping emissions are projected to contribute as much as 17% of global CO2e emissions5,6. The industry’s outsized contribution to criteria air pollutants—12% and 13% of global annual anthropogenic SO2 and NOx emissions, respectively—caused an estimated 403,300 premature deaths from lung cancer and cardiovascular disease in 20203,7.

Mounting political pressure has prompted the International Maritime Organization (IMO) to take regulatory action to reduce GHG emissions consistent with the Paris Agreement. Actions include resolution MEPC.302(72), which aims to reduce annual CO2e emissions by 50% by 2050 from 2008 levels8, and recommended amendments to the International Convention for the Prevention of Pollution from Ships (MARPOL)—whose members cover 99.4% of world shipping tonnage—to prohibit using or carrying HFO in Arctic waters after 20249,10. In concert, IMO’s 2020 emissions standards reduced the allowable marine fuel sulfur content from 3.5% to 0.5% by mass11.

Faced with this tightening regulatory landscape, the marine shipping industry is racing to identify commercially deployable zero-emission alternatives to HFO at a pace sufficient to substantially curb the sector’s emissions and avert catastrophic climate change. Optimistic outlooks for zero-emissions alternatives for marine applications suggest that electrofuels (e-fuels) would increase the total cost of ownership for bulks carriers by 200–600% relative to HFO12. Such analysis prompts additional research into which existing propulsion technologies could achieve parity with HFO in the near-future, particularly battery-electric propulsion. Maersk, the largest shipping company by volume, is already piloting battery hybridization on a containership operating between East Asia and West Africa13. A fully electric 80 m containership, the Yara Birkeland, is expected to begin autonomous operation in Norway in the early 2020s. Similar battery-electric vessel projects are underway in Japan, Sweden and Denmark14,15. However, systematic analysis of the adoption potential for battery-electric containerships has yet to be conducted. 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.

Using the best-available battery costs and energy densities, we examine the technical outlook, economic feasibility and environmental impact of battery-electric containerships. We define two scenarios: first, a baseline scenario using today’s best-available battery costs, HFO costs, battery energy densities and renewable energy prices; and, second, a near-future scenario that tests the impacts of projected 2030 improvements in these variables. By contrast to most previous studies, we treat the volume repurposed to house the battery energy storage (BES) system as an opportunity cost instead of a fixed technical constraint. We specify eight containership size classes and model their energy needs, their CO2, NOx and SO2emissions, and total cost of propulsion (TCP) across 13 major world trade routes—creating 104 unique scenarios of ship size and route length that can be compared with almost any containership operating today. We focus on battery-electric containerships and briefly explore the implications of our results for electrifying other ship types. Our results suggest that over 40% of global containership traffic could be electrified cost-effectively with current technology, reducing CO2 emissions by 14% for US-based vessels, and mitigating the health impacts of air pollution on coastal communities.

## The search for low-emissions pathways for maritime shipping

In the short term, most ship operators have turned to energy efficiency measures such as slow steaming (deliberately reducing a ship’s cruising speed to reduce fuel consumption), route optimization and hull fouling management to meet IMO mandates16. However, the 10–15% emissions reductions achievable through these measures are not sufficient to comply with forthcoming IMO efficiency regulations17,18. Hybrid battery technology has been explored a viable short-term solution to reduce—but not eliminate—emissions from fossil-fuel energy sources. One study suggests a best-case scenario for hybrid systems is only 14% reduction in emissions for dry bulk carriers (comprising 2% of global fleet emissions)19, not substantially better than the existing energy efficiency measures. Small modular nuclear reactors, which have been used in military and submarine applications for decades20, are a viable alternative, but are unlikely to achieve wide-spread deployment in commercial vessels given the regulatory challenges surrounding nuclear proliferation, safety and waste disposal. Marine gas oil, liquefied petroleum gas, liquefied natural gas, methanol and their bio-derivations have received substantial attention as medium- to long-term options, but recent research has questioned the potential of these fuels to reach cost parity and considerably reduce lifecycle GHG emissions21,22,23. Not all transport modes are viable candidates for immediate and direct electrification; commercial jet planes cannot reasonably be electrified until battery pack specific energy increases to three to ten times their current values24. It is within this context that propulsion technologies generated with renewable power have received the most attention. For example, blue hydrogen (hydrogen produced from natural gas with carbon capture and storage) is expected to reduce GHG emissions by only 20% compared with burning natural gas25. Although renewably produced ammonia and hydrogen provide operational emissions reductions, the inefficiency of the production process relative to HFO makes them unlikely to become sufficiently cost-competitive to displace fossil fuels26,27. By contrast, direct electrification is typically five times more efficient than e-fuels in the transportation sector, exclusive of losses from e-fuel transport and storage27.