Fleetzero’s Container Ship Battery-Swapping Scheme May Help Electrify Shipping

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Ships spew a bunch of pollution into the atmosphere as they ply the world’s oceans. According to Fleetzero, a startup based in New Orleans, they account for 2.2% of global carbon dioxide emissions — about a billion tons a year — as well as 15% of nitrogen oxides and 13% of sulfur oxides. You may not know what nitrogen and sulfur oxides are, but trust us on this, you don’t want your loved ones inhaling the stuff, especially if you want them around to celebrate their next birthday.

Introducing Fleetzero

Image courtesy of Fleetzero

Fleetzero has developed a 2-megawatt-hour lithium iron phosphate battery pack that can fit inside a 20′ by 5′ shipping container. Load enough containers onboard (or tow them behind on a barge) to complete a sea voyage, then swap them out when they are depleted for fully charged replacements while the ship is in port to load or unload cargo. Steven Henderson and Mike Carter, the co-founders of Fleetzero, claim that their system is cost-competitive with long haul trucking between port cities — even with first mile and last mile costs taken into account.

“The weird economics of this is that the more ships you have, and the more stops you have, the lower your cost is. The key is to make the batteries swappable — this wouldn’t work for a plug-in vessel,” Henderson tells TechCrunch. “I actually had to model this out on the floor with my daughter’s toy boats.”

Think of it this way: If a ship has enough batteries to go a thousand miles, then unless you’re going exactly that distance every time, you either have too much or too little capacity. And if you only have one large ship that has to swap out batteries at each end, you must keep twice the number of active batteries around — a set to swap out at each destination. But if you split the same capacity among several smaller ships and add more possible stops, suddenly it takes far less battery capacity to move the same amount of cargo, TechCrunch explains.

Image courtesy of Fleetzero

“With smaller vessels we are able to access ports larger container ships can’t — effectively reducing congestion and delivering goods closer to the end consumer,” the company says. The way shipping works today, humongous container ships pile into gigantic ports. All those containers — millions of them every month — cause massive logistical log jams the port has to sort out in order to send them all to the proper freight terminals. Smaller ships can access smaller ports that are closer to local distributors and retailers.

Furthermore, “Unlike large container ships, our vessels are economical to build in domestic shipyards, allowing us to serve in regulated markets where ships must be built in the country they’re traveling within,” the company says. According to Investopedia, “The Jones Act is a federal law that regulates maritime commerce in the United States. The Jones Act requires goods shipped between U.S. ports to be transported on ships that are built, owned, and operated by United States citizens or permanent residents.”

Because the batteries are packaged in containers, they can be loaded and unloaded easily using existing cargo cranes. They can be recharged at the ports or trucked inland to charging stations where the existing electrical infrastructure is more robust. Fleetzero says its container battery system has received approval for vessel propulsion from the American Bureau of Shipping. It also claims that removing the enormous diesel engines and fuel tanks used to power a ship through  the water creates a lot of extra space in the hull where the battery containers can be stored.


People who own electric cars will understand this next part very well. It takes more energy to move a car through the air at 75 mph than it does at 60 mph. By the same token, the energy needed to push a vessel through the water at 25 knots is 8 times more than the energy it is to move the same ship at 12.5 knots, according to The Maritime Executive.

The key to the whole plan is smaller ships (around 700 feet in length) traveling at half the speed of the big 10,000-container ships. The payoff is direct delivery to smaller ports that are closer to the the final consumer. Time is money, and if you can get your product to market faster by unloading it at a port 100 miles away rather than one 1000 miles away, the disadvantage of slower speeds while on the water is nullified.

No Cost Increase

The shipping industry is fiercely competitive, with profit margins measured in pennies per ton/mile. Getting shipping companies to buy in to the idea of battery-powered ships will take some doing. But Henderson and Carter are relying on the same economic factors that electric trucks and buses appealing to fleet operators — lower total cost of operation.

Diesel engines are frightfully expensive to maintain and repair and the cost of fuel can vary significantly over time, which makes it hard to calculate how much to charge customers for carrying their cargo. The cost of electricity is lower and the cost of maintenance is much lower. Not only that, those gigantic megaships are only manufactured in a few places in the world. Building smaller ships could re-invigorate ship building in the United States which in turn would lead to an increase in employment opportunities in communities adjacent to shipyards. There’s a lot to like for the industry as a whole.

Launching Fleetzero

The company has ruggedized its battery packs to withstand the rigors of ocean transportation. It has raised a few million dollars from early investors. Now the task is to load a bunch of those battery packs onto a 300-foot ship and test out the whole shipping and swapping process start to finish. When that is done and the required regulatory approvals are in hand, the company will begin converting vessels in 2025 and getting them into revenue service.

TechCrunch says the idea has a lot of support from fleet owners, port operators, and logistics companies. And let’s not forget the Earth, which could sure use a  break from all the pollution the shipping industry is responsible for every year. Somehow the capitalist system always de-emphasizes the cost of pollution from fossil fuels when in fact that calculation should come first. Kudos to Fleetzero for putting the emphasis where it belongs for the shipping industry.

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Steve Hanley

Steve writes about the interface between technology and sustainability from his home in Florida or anywhere else The Force may lead him. He is proud to be "woke" and doesn't really give a damn why the glass broke. He believes passionately in what Socrates said 3000 years ago: "The secret to change is to focus all of your energy not on fighting the old but on building the new." You can follow him on Substack and LinkedIn but not on Fakebook or any social media platforms controlled by narcissistic yahoos.

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