“In two weeks we face the full brunt of the South Westerlies and we’ll see what the sea is going to do to us.”

Simon Gillett has a habit of talking about the device his company, Wave-tricity, has created as an extension of himself. This must be a nerve-wracking time.

The Ocean Wave Rower, launched into West Wales’s Milford Haven estuary in March, is undergoing a period of initial testing before it gets towed out to the open seas.

It’s an attempt to crack one of the toughest engineering problems in renewable energy: how to extract usable energy from the ocean waves, and do it affordably.

While wind and solar power have grown into major industries over the past decade, so-called marine renewables – technologies to harness the power of the oceans – have struggled to get established.

Earlier this year, the Energy Technologies Institute (ETI) warned that wave power was far too costly and should not be a priority for renewable energy development. But that has not stopped the nascent industry from pushing ahead with trials.

As well as the start of Wave-tricity’s experiment, March saw Finnish company Wello Oy launch its boat-shaped wave energy converter at a test site off Orkney. Australian company Carnegie, meanwhile, is pressing ahead with its £60m project, initiated last November, to test energy-generating buoys in Cornwall, with commissioning expected in 2018.

We need Land Rovers, not Lamborghinis

Gillett is uncompromising about the wave industry’s slow progress to date. “I’ll be quite blunt about that, I think the industry’s failed,” he says, citing the fact that no company is making money from wave power anywhere in the world.

But the problem, he says, has been with the approach, not the basic idea: companies have prioritised clever ideas for turning complex wave motion into power, rather than starting with a design that would be robust to the ocean.

“I like to use the car analogy. A lot of people are hunting for efficiency and performance to become the Lamborghini of the seas. We’re looking for robustness and longevity and want to be the Land Rover of the seas,” he says.

Even tidal, which is further advanced than wave power, has also struggled to make headway and can only boast one large-scale project – MeyGen in the Pentland Firth, the strait separating the Orkney Islands from the Scottish mainland. And that too is at an early stage. The £1.3bn Swansea tidal lagoon received a significant boost in January when a government-commissioned review by former energy minister Charles Hendry backed the project, but is yet to get the green light.

Part of the difficulty for both wave and tidal is the enormous challenge of operating at sea. The kit has to be durable to the mechanical stresses of the ocean and resist the corrosive effects of salt water. There are also fears that underwater turbines or wave devices with moving parts could injure sea mammals, fish and diving birds if not sited appropriately.

Wave power faces specific engineering challenges, explains Stuart Bradley, ETI’s strategy manager. Firstly, there are two types of energy up for grabs – potential energy, the up and down motion of the sea’s surface, and kinetic energy, the wave’s speed. Capturing both at the same time has proved difficult.

Secondly, the stresses placed on the device by rough seas can be exceptionally high. Bradley compares the engineering problem to a car’s suspension. In that case, the load created by, say, hitting a pothole is around five to ten times the average load during normal driving. But for a wave power device that ratio is much higher. The difference between a storm load and normal wave activity can be 30 to 50 times.

That poses some very difficult engineering questions that require technological answers akin to those in extreme applications, like military structures and spacecraft, says Bradley.

Finnish company Wello Oy launched its Penguin wave energy converter at a test site off Orkney in March. Photograph: Picture by Wello

The next decade

Some of those answers are expected to come from materials science. Wave Energy Scotland, which channels cash from the Scottish government gave 10 companies £200,000 to £250,000 each last year to develop new materials, with much of the focus on developing lightweight, flexible polymers.

Wave energy developers are also learning from past failures, says Bradley. Early leaders Aquamarine Power and Pelamis Wave Power – known for installing a floating snake-like design off the coast of Portugal – have gone bust, but some of their technology could make it into future devices, he says.

If it keeps its nerve, the UK has a chance of being the world leader in a future wave and tidal power industry, says Neil Kermode, managing director of the European Marine Energy Centre (EMEC) in Orkney. The country’s research in the field is currently ahead of the rest of the world, he says

But he points to the history of wind energy as a cautionary tale. “When [the UK] did experimental work [on wind energy]...we moved the whole game on enormously,” he says. “And then we lost our nerve. In the meantime the Danes and the Germans stayed with it.”

A decade down the line, he continues, German and Danish companies like Siemens and Vestas dominated the global market.

Sign up to be a Guardian Sustainable Business member and get more stories like this direct to your inbox every week. You can also follow us on Twitter.