Ocean-going vessels, most of which are powered by heavy fuel oil, produce significant amounts of CO2 and nitrogen oxide emissions. However, shipping companies are unlikely to start electrifying them until the economic case for electrification becomes clearer.
A new study from the University of California, Berkeley and Lawrence Berkeley National Laboratory indicates that nearly half of the world’s container ship fleet could be cost-effectively electrified, using current technology.
“We outline a pathway for container ship battery electrification this decade that electrifies over 40% of global container ship traffic, reduces CO2 emissions by 14% for US-based ships and mitigates the effects of air pollution on the health of coastal communities,” write study authors Jessica Kersey, Natalie D. Popovich, and Amol A. Phadke.
For the new study, which was published in the journal Nature, the research team modeled a wide variety of container ship sizes, against the backdrop of 13 major global trade routes.
“Previous studies of ship electrification have relied on outdated assumptions about battery cost, energy density values, and available space on board,” the researchers write. “We show that at battery prices of $100 per kWh, electrification of intra-regional trade routes of less than 1,500 km is economical, with minimal impact on ship load capacity.”
The study found that electrified container ships have an economic advantage over older ships, even when the environmental and health costs of fossil fuel-burning ships are excluded. According to the researchers, the environmental and health damage caused by ICE container ships is at least three times the operating costs. “The inclusion of environmental costs increases the economic scope [of electrified ships] 5,000 km,” the researchers note. They estimated the environmental and health footprint of an electrified ship to be around 1/12th that of an ICE ship.
Expected future advances in battery technology will dramatically increase the number of routes that can be served economically by battery electric vessels. “If the batteries reach a price of 50 kWh, the economic range almost doubles,” the researchers write. In a few years, as the costs of large ICE container ships continue to rise, as electrified alternatives become increasingly cost-effective, fossil fuels could become much more expensive.
As is the case with on-road vehicles, different nautical use cases might be better served by different battery chemistries. Ships serving short routes require less power, but need to recharge quickly, so an LFP chemistry, which offers fast charge rates and long lifespans, might be the best choice. Long-range ships typically spend a lot of time in each port and could benefit from the higher energy density of NMC batteries.
The size and weight of battery systems are not trivial considerations. A container ship serving a 5,000 km route would require approximately 6.5 GWh of battery capacity. For a ship with a range of 20,000 km, the batteries and motor would require 32% of the ship’s load capacity, or 2,500 twenty-foot equivalent units (TEUs).
“The primary technical constraint for battery electric container transport is the volume of the battery system and electric motor relative to the volume occupied by a vessel’s existing engines, fuel storage and mechanical space,” write Researchers. However, they found that “as load capacity increases, the percentage of the total volume of load capacity occupied by batteries decreases, since larger vessels generally have lower energy requirements per unit of load capacity.”
A Neo-Panamax container ship serving a route of less than 3,000 km would indeed require less space for batteries and motors than the volume currently occupied by combustion engines and fuel tanks.
As for the infrastructure needed to charge such gargantuan batteries, the researchers predict it will be affordable, due to typical port dynamics. Most berths are occupied more than 50% of the time, and at 50% utilization, the study model indicates that the levelized cost of a 300 MW charging station would be around 0, $03 per kWh.
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