The world’s largest battery-electric ferry has begun carrying passengers between Argentina and Uruguay. With a massive 41 MWh battery, equivalent to more than 500 electric cars, the 130-meter catamaran marks a milestone in maritime electrification.

But its relatively short 55-km route raises a bigger question: can batteries ever power ships across much longer distances, or will hydrogen and alternative fuels have to take over?

The China Zorrilla, a 130-meter aluminum catamaran built by Australian shipyard Incat Tasmania, completed its first commercial crossing between Buenos Aires and Colonia on October 22. Operated by Buquebus, it can carry 2,100 passengers and 225 vehicles and reach speeds of 25 knots (46 km/hour).

Named after a celebrated Uruguayan actress, the ferry was originally designed to run on diesel and LNG. During construction, however, its owners decided to abandon combustion engines entirely.

The result is an extraordinary electrical installation: more than 250 tons of batteries, supplied by Corvus Energy, with 41.2 MWh of storage capacity.

Eight electrically driven waterjets propel the ship across the Río de la Plata without exhaust emissions or the characteristic noise and vibrations of diesel engines.

A world record with qualifications

Incat calls it the world’s largest battery-electric ship, though the distinction depends on the definition used. Norway’s Bastø Electric ferry is longer, at 139 meters, while China’s COSCO Green Water 01 container vessel reportedly has a larger, 50 MWh battery installation.

What makes China Zorrilla exceptional is the combination of its size, passenger capacity, speed, and entirely electric propulsion.

The investment is equally impressive. The World Bank’s International Finance Corporation puts the overall project at approximately $184 million, including charging and electricity transmission infrastructure.

Why does a ferry need so much electricity?

Unlike a car rolling on wheels, a ship must overcome water resistance, which is roughly 800 times denser than air. Fast vessels also consume considerable energy generating waves.

Planing hulls can reduce drag by lifting much of the vessel out of the water, but this requires substantial power. The 50-meter Mangusta 165 REV superyacht, for example, needs 10,400 hp (7.8 MW) to reach 35 knots. China Zorrilla takes a different approach, using two long, slender, wave-piercing hulls to minimize resistance without planing.

The relationship between speed and energy demand is particularly unforgiving. Under a simplified model, reducing speed from 25 to 20 knots could cut propulsion power requirements by almost half.

That doesn’t mean ships are inherently inefficient. Large, slow cargo vessels can transport goods with exceptionally low energy consumption per ton-kilometer. High-speed passenger ferries are a different proposition.

Dedicated high-power charging infrastructure at both terminals makes China Zorrilla’s approximately 90-minute crossing possible. Reported charging times range from around 40 minutes for a partial recharge to considerably longer for a full battery.

Colonia’s electricity infrastructure has been upgraded to provide approximately 15 MW of capacity. At that power level, replenishing just 10 MWh requires at least 40 minutes, excluding losses.

Actual electricity consumption per crossing has not been publicly confirmed, making a reliable comparison with conventional ferries difficult.

Would hydrogen be a better solution?

Hydrogen contains considerably more energy per kilogram than batteries, potentially allowing longer voyages without carrying hundreds of tons of electrical storage.

But producing green hydrogen, compressing or liquefying it, and converting it back into electricity through fuel cells involves substantial losses.

While direct battery propulsion can convert around 80% of grid electricity into useful propulsion energy, a green-hydrogen pathway might deliver only around 30-40%, depending on the system.

Ammonia, increasingly considered for ocean-going shipping, offers easier bulk storage than hydrogen but adds conversion losses and significant toxicity concerns.

Belgian shipping group CMB.TECH recently demonstrated its potential with the Mineral Europa, the world’s first ammonia-powered dry bulk carrier, capable of transporting 210,000 tons of cargo. However, using such a toxic fuel on passenger ferries would raise particularly demanding safety questions.

For a short, predictable route with charging facilities at both ends, batteries are therefore likely to be the most energy-efficient solution. Hydrogen and alternative fuels become more attractive as distances increase and recharging opportunities diminish.

Europe follows with even faster electric ferries

The technology is already spreading beyond South America. Incat is constructing three 129-meter battery-electric catamarans for Danish operator Molslinjen, each carrying nearly 1,500 passengers and 500 cars at speeds exceeding 40 knots (74 km/hour). The first is scheduled to enter service in February 2028.

Each will accommodate approximately 1,500 passengers and 500 cars, with a 45 MWh battery and a projected maximum speed exceeding 40 knots (74 km/hour). Charging infrastructure capable of delivering tens of megawatts will be required.

The Australian shipbuilder has been pioneering lightweight, wave-piercing aluminum catamarans since the 1980s, expertise that now gives it an advantage in battery-electric propulsion, where every ton saved matters.

Its main rival, fellow Australian shipbuilder Austal, is pursuing alternative-fuel technology for a new generation of high-speed ferries. Meanwhile, Norwegian and Dutch yards have already established themselves in electric shipping on shorter routes.

Ironically, China Zorrilla itself could not make the journey from its Australian shipyard to South America on battery power. It had to be transported aboard Boskalis’s heavy-lift vessel Black Marlin.

That contrast sums up the challenge facing maritime transport. Batteries can move enormous vessels quickly and cleanly, but only over distances that allow regular access to powerful chargers. For ocean-going ships, the search for a practical alternative to fossil fuels is far from over.