Fixed Routes Make Passenger Ferries a Practical Test for Battery Shipping

Shipping is difficult to decarbonize, but passenger ferries offer a more practical place to start than ships that spend weeks at sea. They travel fixed routes over short distances, on schedules that let operators estimate both the energy needed for a crossing and the time available to recharge in port.

That predictability matters because batteries remain heavy and charging infrastructure is not available everywhere. Shirley Meng, a battery researcher, says ferries are a good setting for new technology because route, load, ship size and design parameters can be planned and controlled. David Stringer, a shipping analyst, makes the operational point: ferry operators know how much charge a particular journey requires and how long the vessel can recharge while docked.

Ferries are a small share of shipping’s emissions, but they carry people, vehicles and cargo in coastal and urban settings. A study for trade association Interferry, using 2019 data, estimated that ferries carried more than four billion passengers a year and supported $60 billion in global GDP. Meanwhile, Stringer says international shipping emitted about 740 million tons of carbon-dioxide equivalent in 2024—roughly 1.4% of global emissions, more than Germany or South Korea and slightly less than Canada.

The conditions for electrification have improved. Meng says lithium-ion batteries have made substantial gains in cost, performance and safety over the past three and a half decades, making them more accessible to shipping companies considering battery power. A chart shown with her explanation tracks falling lithium-ion battery pack prices alongside rising energy density from 2010 to 2026. Pressure to cut maritime greenhouse-gas emissions is another driver.

In Tasmania, shipbuilder Robert Clifford’s company, Incat, is building a battery-electric ferry for Uruguay’s Buquebus. Known internally as Hull 096, the vessel is named China Zorrilla, after the Uruguayan actress. It is designed for a regular crossing of the Río de la Plata between Uruguay and Argentina: about 32 nautical miles each way, taking roughly 90 minutes.

The ferry is 130 meters long and 32 meters wide. It has three floors and is designed to carry 2,100 passengers and 225 cars, as well as a duty-free shop. David Riseley of Incat says it can operate at 25 knots.

Its power system comprises 5,016 lithium-ion batteries, with more than 40 megawatt-hours of capacity—enough energy, by the comparison used in the source, to power around 550 electric cars. The batteries sit in four rooms; Riseley says one room holds 1,250. They connect directly to one another rather than requiring scaffolding or additional brackets, reducing the space and weight they take up. Stringer says marine batteries are also designed with stronger protection against saltwater than batteries in electric cars and trucks.

The battery system is not the only weight to consider. Riseley puts the battery arrangement at 250 tons. Traditional fuels such as heavy diesel, high-speed diesel and liquefied natural gas carry more energy per unit of weight than batteries. Stringer describes the consequence plainly: electric ships need many batteries, and more batteries mean more weight.

The comparison Incat makes takes in the complete propulsion system, not just batteries against fuel. Meng notes that electric drivetrains can be light once the engine and supporting structures of an internal-combustion vehicle are removed. Incat says the batteries and electric propulsion system on Hull 096 weigh less than the equivalent fuel-powered setup when that setup is loaded with fuel.

Eight 2.4-megawatt electric motors drive eight waterjets, which propel and steer the ferry. Clifford says the ship has only half the power normally seen on a ship. A Danish customer wants a 38-knot vessel; Clifford says achieving that speed will require substantially more batteries and electrical power, and will make the ship less economical.

The costs remain uncertain. Clifford says batteries are expensive, even though electricity is relatively cheap: the operator buys the battery, he says, rather than buying fuel every day. Stringer says it is not yet clear whether electric ferries are more profitable to produce than conventional ones.

And the vessel is only part of the investment. Charging requires suitable port equipment and enough electricity transmission capacity. Stringer says governments have supported both vessels and the infrastructure needed to operate them. In Hull 096’s case, Caroline Hyde reports a total investment of $184 million, including financing from Banco Santander Uruguay and the World Bank’s International Finance Corporation. Part of the financing went toward charging infrastructure, with charging estimated to take about 60 minutes per trip. Uruguay also invested $20 million in grid upgrades and ship charging at the port of Colonia.

The infrastructure problem will vary by port, country and market. Clifford says Incat is comfortable with ports coming online one at a time; Denmark, he says, expects to have the required power available by the time its ships are delivered.

In August 2026, China Zorrilla began its journey to South America aboard the heavy-lift vessel Black Marlin. Its planned route illustrates where battery propulsion is most plausible: regular, relatively short crossings with known charging points.

Clifford expects 95% of short-distance ferries to go electric, but says ocean-crossing ships will not. Stringer similarly sees little near-term role for batteries in long-distance shipping, where vessels cover immense distances far from charging infrastructure. Battery swapping is one approach some Chinese companies are exploring for larger cargo ships; for very large and long-distance ships, the source points to other possibilities, including hydrogen carriers and nuclear power.

Electric ferries remain a tiny part of the global fleet—Stringer estimates far less than 1% of ships in the relevant category have gone electric. He argues that fleet share is not the whole measure of their significance: ferries can prove the technology in a setting where routes and charging needs are manageable, and show what may work for other smaller ships on shorter journeys.