Water taxis powered by green energy could soon start running between Cardiff and Bristol.
Plymouth-based luxury boat firm Patriot Yachts is developing two hydrogen-powered passenger ferries to operate on the route.
The boats, which cost a total of £1m, will be able to transport about 100 people across the Bristol Channel between the two cities.
They will use solar panels and wind turbines, making them self-sufficient.
Patriot Yachts director Connor Johnson has ordered the boats from Turkey, which will be fitted with the technology, with trials across the water planned for later this year.
Describing the hydrogen propulsion technology he is fitting the boats with, Mr Johnson said: "You have a hydrogen fuel cell, then you have pure, green electric to charge it. That's it.
"The only thing that would come out of the emissions would be water vapour, rather than carbon monoxide and harmful things."
He hopes the boats will arrive from Turkey in the next few weeks and his team is designing the engines ready to be fitted.
The firm is also working on a project to run a 500 to 700-seater ferry between Ilfracombe and Cardiff or Newport.
Another project involves hydrogen-propelled aircraft which would be used for short-haul flights, carrying 20 to 80 passengers at a time
"We are in talks with a company in Serbia to develop them, he said.
"We will be designing a new hydrogen engine and new aircraft design for both the private and commercial sectors in aviation. It is a great place for reducing carbon footprint."
Conservative transport spokesman Russell George said it was an "exciting and innovative transport option".
"I am looking forward to learning more about the trials due to take place later this year, and Patriot Yachts' future plans for a larger vessel to operate from Wales to Ilfracombe," he added.