Hydrobike

The fuel cell has come of age with the manufacture of the first hydrogen-powered motorbike. Stuart Nathan reports on its development, from brainstorming to production.

Fuel cell vehicles are becoming a reality, with trials of fuel cell-powered buses well underway in several cities. But for personal transport, fuel cells are still seen as a technology of the future.

Public and industry alike tend to think the cells are not yet advanced enough; the infrastructure isn’t there; and nobody has a clear idea what a fuel cell-powered vehicle would actually be like.

Intelligent Energy, a fuel cell developer based in London and Los Angeles, has different ideas, however. Its ambient pressure PEM stacks generate power densities of 2.5kW/l; are lightweight; require no external cooling circuit; and can start at temperatures well below 0°C.

‘This is clearly the right technology for commercial applications. It exists now, and it works. And we wanted to demonstrate that to people,’ said Dennis Hayter, IE’s vice-president for business development.

What IE needed, Hayter said, was a design ‘that would make people want to try it out before they wanted to know how it worked’, and for that the company turned to London product design consultancy Seymourpowell.

The result was the ENV bike, the world’s first fuel cell-powered motorbike, capable of a top speed of 50mph and with a range of up to 140 miles on a single fill of hydrogen. The journey to the ENV was challenging, said Nick Talbot, director of Seymourpowell and chief designer on the project.

‘In the early stages it was by no means certain that it was going to be a motorcycle,’ he said.

After an extensive brainstorming session with the client, during which options such as small-scale domestic electricity generators were discussed, the teams settled on the motive route.

‘Everyone’s seen little fuel cells to recharge mobile phones and so on, and the response is, “So what”,’ he said. 

‘What hasn’t been seen is something really accessible and exciting, that proves how able this technology is. Because IE wanted to use their ambient stacks, as they’re very simple, we said let’s build a motorbike. It’s perfect, because it shows just how small and lightweight an integrated power unit driven by hydrogen can be.’

Seymourpowell has experience in designing motorbikes, with products such as the BSA Bantam and the Norton F1 under its belt. Talbot, a dedicated biker himself, believes this experience was instrumental in winning the contract.

But designing the ENV had an important difference from other two-wheeled projects.

‘In the past we’ve had an input on the chassis and the forks and so on, but usually we know what the engine’s going to be, and we design around that. In this case we started with nothing.’

The IE fuel cell was a benchtop unit not optimised for motive applications; there was no set hydrogen storage option, and nobody knew what the generating unit would look like. One thing that was specified by IE’s then chief executive, Harry Bradbury, was that the generating unit, dubbed the Core, should be removable from the bike.

‘He wanted to make the fuel cell a consumer product, as iconic as an Apple iPod. He wanted people to be able to take it out of the bike — so that it could power other things, for example,’ Talbot explained.

This added extra complexity to the project, and it meant that ‘the Core designed the bike, and the bike designed the Core’, he said. The Core, which generates 1kW of energy, had to be compact, provide protection for the hydrogen and the fuel cell itself, and to be balanced so the bike would remain stable.

The team decided early on that components should be available and approved now, which meant that a high-pressure cylinder, rather than hydrides, was the only practical option for hydrogen storage.

‘Finding a bottle that was approved to take very high-pressure hydrogen was tricky, but once we had that the key was minimising the weight of holding everything together,’ he said.

The team considered several options, including carbon monocoques and a casting with integral pipework. But the choice made was high-grade aluminium, folded, pressed and multi-riveted.

‘If it’s good enough for aerospace, it’s good enough for the Core,’ said Talbot. The final shape of the Core is a rounded cuboid. ‘The proportions are quite similar to a computer, but we didn’t want it to look like that. We ended up with this incredibly compact, pure form, and we added the brain-coral decoration because of the huge surface area of that sort of structure; it implies power in a small space.’

Fitting the 17kg Core into the bike was another matter. For stability it has to sit low in the bike frame. ‘And it had to go in the top — we couldn’t risk it falling out of the bottom,’ Talbot said.

The bike was based on a hollow-cast aluminium frame, which provides extra protection for the hydrogen bottle, but the Core had to slot inside a very constrained vertical drawer in that frame.

‘We designed a mechanism with a gas strut to lift the Core out of the hole. And it had to look effortless. It was probably the biggest headache, to get all those elements working together in an elegant way.’

The styling of the bike itself was a thin line between standard design and a more streamlined, smooth approach. ‘There’s a headstock at the front and a swinging arm at the back, and we had to decide how to put them together, and how to make sure there’s enough structure to support the rider. But we also wanted it to be an object of beauty. We wanted 55-year-old ladies to want to have a go, but at the same time we wanted the motorbike magazines to think, “Wow, this is quite quick! It’s not a Fireblade, but it’s good fun!”’

This is why he opted for the smooth aluminium frame and arm, rather than a tubular construction. It also dictated the design of the ballast battery housing in the lower section, which sticks out on either side, like the crankcase on a standard engine.

‘It’s a smooth surface, with no visible rivets or anything, but it looks as if there’s a bit of machine trying to get out.’ The final design is certainly striking, and is versatile both on and off-road. It runs off a 6kW electric motor, with no gears, and is almost completely silent. The pressurised hydrogen storage makes it fast to refuel — less than five minutes, from a high or medium-pressure tank.

‘One thing that’s impressed me is how easy it has been to get the hydrogen,’ Talbot said. ‘I’ve refuelled at Los Angeles airport and at an electric vehicles exhibition. It really is practical right now.’

Currently, there are only two ENVs, but the bikes are doing the rounds of car, bike and electric vehicle shows, and the plan is to make a production model within the next few years.

‘We’ll have to undergo extensive safety tests, and that’s almost certainly going to lead to design changes,’ Talbot said. ‘We might have to go to all-carbon construction, or allow more space around the hydrogen bottle to decelerate it in case of a crash.’

The price of the first generation of bikes is likely to be around £8,000 — much higher than a petrol vehicle with comparable performance.

But Talbot is certain it will be a success. ‘I’ve ridden this thing around a lot, and I’m a complete convert,’ he said. ‘As soon as I can get my hands on one of my own, I’ll definitely put my order in.’