Yamaha plans to show hydrogen-powered outboard engine

The prototype, teased in a couple of images released on social media, show what looks like a conventional Yamaha powerhead but features what appear to be fuel lines adapted to using hydrogen.

The engine shown in images is based on Yamaha's flagship XTO Offshore, a 5.6-litre V8 that produces either 425hp or 450hp depending on its state of tune.

“Marine products run through water and are thus subjected to water resistance, requiring significantly more energy for propulsion than land vehicles,” Yamaha said in a statement accompanying the images.

“Additionally, the performance and engineering requirements for marine products can vary widely depending on the usage environment – such as the ocean, rivers, or lakes-as well as the usage itself, from commercial fishing to recreation.

“In order to achieve carbon neutrality with marine products while facing such challenges, the company is promoting a multi-directional development approach, looking to other new energy sources and technologies in addition to its electrification efforts.”

A switch to hydrogen power will be an important step change for Yamaha, which has already developed the Harmo electric outboard system that uses a transom-mounted rotating pod, a joystick and a throttle control

The technology will mean that the Japanese outboard engine maker will be able to keep its conventional four-stroke engine range, but adapt it to run on the new fuel. Hydrogen will burn with atmospheric oxygen in an engine’s cylinder just like petrol, but instead of producing harmful emissions, the only thing coming out of the exhaust is water formed after the hydrogen fuel is burned.

The prototype hydrogen engine will go on show at next year’s Miami International Boat Show, which will run from February 14-18.

However, using hydrogen as a fuel out on the water will not be without its challenges.

To start, hydrogen needs to be kept extremely cold and must be pumped at very high pressure to fill a tank, making refuelling a bit more tricky than using a conventional liquid fuel such as diesel or petrol.

Hydrogen is also difficult to store, with the atom so small it can easily slip through a tank’s wall and leak into the atmosphere. In the automotive world, a hydrogen car will lose about half its fuel over a month due to leaks.

Hydrogen fuel tanks also need to be very bulky to hold enough fuel at the right temperature and pressure, meaning they may need to be designed into a boat that’s made to run on the gas.

Marine engine brands such as Yanmar are developing hydrogen systems but are using fuel cells to convert hydrogen into electricity that is then fed into batteries used to power an electric engine.

Meanwhile, Volvo Penta is developing a new line of marine engines that will be able to run on a mix of diesel and hydrogen to reduce emissions.