Research into the costs and feasibility of battery-electric ships
Converting part of the U.S. shipping fleet from internal combustion engines to battery-electric systems could significantly reduce greenhouse gas emissions and be largely cost-effective by 2035, according to a new study from Berkeley Lab researchers recently published in Nature Energy.
Shipping represents 3% of total U.S. greenhouse gas emissions from transportation, making it an important decarbonization target. But electrifying ships is a greater challenge than electrifying cars from both a technical and market perspective. A ship is a much larger capital investment than a car and has a lifespan of decades. Although better battery technology has led to longer-range EVs in recent years, ships are much heavier than cars and can travel very long distances between ports. These heavy weights and long distances have led some to think that electrifying shipping is not feasible.
The researchers decided to test that assumption, said Won Young Park, head of the study and an energy policy researcher at Berkeley Lab.
“Our analysis includes the feasibility of electrification for 100% of all voyages, while also examining the exclusion of a small percentage of very long one-way voyages, which could potentially be addressed through optimized multi-ship operations,” he said. “Decreasing battery costs combined with increasing battery energy density, cleaner networks, optimized vessel operations and valuing battery second life create a unique electrification opportunity in domestic shipping.”
The researchers analyzed U.S.-flagged ships with a gross tonnage of less than 1,000, including mainly passenger ships and three types of tugboats. They identified 6,323 such ships. Of those, 2,722 had enough data from the Automatic Identification System, an automatic ship tracking system, to understand the length and patterns of the voyages they made.
Park and his colleagues found that eliminating just 1% of the longest voyages made electrifying the ships much more feasible, making batteries two-thirds smaller than would be needed for the longest voyages. For passenger ships, the size could be reduced by 85%, they found.
How much electrification reduces emissions depends on the carbon intensity of the electricity used for charging. These 6,323 ships contribute 9.5% of total U.S. domestic shipping emissions, according to the newspaper. The researchers looked at three scenarios for the carbon intensity of the electricity grid over time. Scenario one was the status quo, scenario two was decarbonizing the electricity supply by 95% by 2050, and scenario three a more aggressive decarbonization of 95% by 2035. Retrofitting these ships would reduce maritime CO2 equivalent emissions by 2035 can reduce by 34-73%, with the highest reduction. achieved via the third scenario.
The researchers also looked at how electrifying shipping could be cost-effective, meaning that converting to battery electrics would cost the same or less than operating an equivalent ship with an internal combustion engine. For ships with internal combustion engines, the total costs include fuel, operation and maintenance, and the social costs of CO2 equivalent emissions and air pollution. For the battery-powered ships, the total costs include batteries, charging, operation and maintenance, charging infrastructure costs, the social costs of CO2 equivalent emissions and the value of the battery during its second life at the end of the first life. The researchers again compared these costs across scenarios, including the percentage of total trips, the CO2 intensity of the electricity grid, and different cost scenarios for the battery system and charging costs.
Under the scenario of 95% low-carbon electricity by 2035, electrifying up to 85% of these ships that make 99% of annual voyages would be cost-effective by 2035, they found.
The researchers also studied how much charging energy the ships need for successful electrification. They found that about half of charging needs could be concentrated in 20 U.S. ports.
“The electrification potential is concentrated in relatively few ports, including New York – New Jersey, New Orleans and Houston,” said Hee Seung Moon, a postdoctoral researcher from Berkeley Lab and first author of the paper. “This implies that concentrating infrastructure investments on these ports will facilitate the electrification of ships.”
“Our analysis provides an essential first step in understanding battery-electric shipping options,” said Park. “It lays a foundation for future research and policy development to identify optimal locations for prioritizing battery electrification based on individual ship activity and local network emissions.”
This research was supported by the U.S. Department of Transportation’s Maritime Administration (MARAD).
Research report:Research into the cost and emission impact, feasibility and scalability of battery-electric ships
