April 19, 2024

I, Science

The science magazine of Imperial College


Zoë Corbyn takes a test-drive in a Twike, the world’s most efficient motorised vehicle, and discovers why a pair of mechanical engineering students are hybridising it.

“The Twike isn’t actually a car,” Imperial College mechanical engineering lecturer Michael Lamperth says, “it’s a tricycle”. And it is. Perhaps. We agree that `egg on motorcycle wheels’ would probably make a better description, as we adopt a reclining position in the capsule, secure the perspex window above us, fasten our seat belts and swing out into heavy London traffic…

In September last year, Lamperth became the proud owner of only the second Twike to reach UK shores, though there is apparently now a third. Swiss made, the unusual thing about the Twike is that it is electric powered, though it can also come supplemented with pedals. While conventional cars need petrol, the Twike need only have its battery recharged, which means no fumes to clog our capital’s air. “I just plug it into the mains and I know that the energy mix is not really green in this country. If I was to charge it in Switzerland it is different because there is lots of renewable energy there already. But nothing would stop you from having a solar charging station at home” says Lamperth, of the Twike’s green energy possibilities.

Taxi drivers and tourists gawk as we drive through leafy Hyde Park. We will be photographed, Lamperth assures me as he operates the joystick steering control. We take a look at at the monitoring panel over the noise.hmmm.all looks good. Our battery voltage is 360 volts, we’re running at an optimal battery temperature of 36 ° C, cruising at about 40 km per hour and we’ve got about 68 km until we need to recharge…

Of course, electric cars aren’t new. Commercial hybrid cars, like the Toyota Prius, have been on the market for some time. Twikes themselves have been in production since 1996 and there are now about 1000 spread across the globe. There is even a `Twike Club’ for enthusiasts. New prototypes are currently in design, and the company has just moved to Germany. But the different thing about a Twike is in its efficiency, ten times that of a conventional car. The Twike gets the equivalent of 142 km per litre compared to the 7 – 16 km that can be squeezed out of an ordinary car, or the 23 km that a Toyota Prius can manage. It is the most efficient motorised vehicle around.

“A normal car has about 25% efficiency – so by filling your tank up you are actually throwing away three-quarters of the energy you have got in your petrol” Lamperth explains. “An electric vehicle hasn’t got this problem”. The efficiency of the Twike is enhanced by its futuristic regenerative braking system: because it is electric, the motor can be used as a generator and energy recouped while braking. About 30% of the energy that goes into the vehicle to accelerate can be put back into the batteries. There is also a conventional braking system, just in case.

The Marble Arch roundabout looms. Three lanes of solid bus: and crikey we’re close to the ground. Now is not the time, but I blurt it out: “So, have there been any accidents?” I’m not sure I like the answer. There was a fatal accident: a Twike squashed between two lorries. It had no chance. I hold my breath and let Lamperth navigate in peace. He eases us deftly into Park Lane. I ask whether Sports Utility Vehicles (SUVs) are any better at spotting Twikes than lorries. “Sports vehicles are a problem, because they are quite high up and quite heavy. Drivers are much more concerned about their safety than the safety of others. I’d agree with Ken’s verdict,” replies Lamperth. Mayor Ken Livingston last year famously dismissed SUV drivers as idiotic and considered levying them with their own congestion charge. It is a charge electric vehicles like Twikes are already exempt from and they also get free parking…

But while Lamperth may have some fun occasionally driving his Twike to Imperial from his home in Woking, it has also turned out to be a useful teaching aide and project for a pair of third year mechanical engineering students. “I thought it was a great chance to bring it here for students to work with, to get a feel for the technology available, what could be done and to have a chance to hybridise it, which will improve the range. This is one of the problems with electric vehicles – that you have a limited range. You can’t travel too far before they need recharging.”

So, under Lamperth’s guidance, students James Skelton and Giles Smith are hybridising the Twike: putting in another power source to enable the batteries to be triple charged. Rather than around 65 km per charge, the new range will be closer to 200 km. “For our project we selected an internal combustion engine and we’re connecting that to a generator and will use the power from that to charge the batteries” says Skelton. Smith is working on the electronic control system: “The output from the generator is AC current and the battery is DC current so we need to rectify this so it is all DC current and then amplify it so it is the right voltage” he explains. Of course, says Lamperth, you could argue that you don’t need to hybridise the Twike at all because the best use of it is for short trips – shopping and school runs. But he doesn’t buy it – he thinks it is good to have the option to go a bit further.

And then soon we are back at Imperial, the mini Twike adventure over. Though not before being photographed outside Harvey Nichols: clearly too fashionable to be ignored. “I’ve never been photographed so much as driving the Twike through town and then people come and talk to you and you can explain to them about the efficiency,” says Lamperth. “It is a way of showing what is actually possible and not just talking about it, it is a forerunner of what is to come.”