Motor manufacturers have been presenting their vision for the future of boat engines at the world's largest boat show in Düsseldorf.

Hybrid and electric engines may sound like something more appropriate at a car show, but greener, cleaner boating is catching up - and perhaps even overtaking. Amongst the displays at boot Düsseldorf, solar propulsion has been generating buzz, prompting some visitors to ask whether it will be a viable alternative for water transport before it is for land transport.

The Greenline 33, for instance, from Slovenian design studio J&J Design, will shortly enter production as one of the world's first hybrid boats. Photovoltaic cells on the roof charge the batteries to be used on the electric motor, capable of a top speed of around 5.9 knots for around 9.2 nautical miles. Theoretically, the boat could run limitlessly using solar power at the slower speed of 2.4 knots. For high voltage usage such as faster speeds, or on-board features such as air conditioning, the 75 hp diesel engine can be used.

Kayak design house Klepper has also produced a lightweight solar motor, powered by two panels that affix to the fore and aft of its collapsible boats. The product is designed for rowers who like to take a bit of a break from rowing without necessarily needing to moor up, as well as for the journey home, which generally means rowing against the stream.

Even fuel cells have made an appearance - on board the Riviera 600 from Austrian boatyard Frauscher. The 6-meter craft uses hydrogen fuel cells, permitting travel for 43 nautical miles at 4 knots, alongside an onboard battery which can deliver temporary power in case the fuel cells are forced to shut down for safety reasons.

The boot Düsseldorf show runs through January 31.