Fast-car specialists are pushing their environmental credentials as they go electric.
A flash of lightning is being unleashed at motor shows this summer. Designed and developed by The Lightning Car Company in Peterborough, UK, the Lightning GT electric car has impressive engineering roots. Its originator, Arthur Wolstenholme, also created the Ronart series of Jaguar-powered racers and Vanwall high-performance sports cars. His colleagues hail from the likes of McLaren and Lola. Not surprisingly, the final prototype boasts a wealth of cutting-edge technology.
For starters, the car’s body is made from lightweight carbon fibre and Kevlar. This so-called ‘skin’ incorporates the same aluminium honeycomb cells used in Formula 1 motor racing that protect drivers by crumpling on impact. These cells are used in the front, rear and sides of the car as well as around the batteries.
The vehicle’s chassis has recently been re-designed mainly to accommodate the all-important battery pack.
The final iteration sees the pack split between the front and rear bulk-heads, which as Chris Dell, managing director of The Lightning Car Company explains, balances the weight, optimising the vehicle’s handling.
“We’ve really engineered the car backwards to make sure it not only handles but also that the cabin area isn’t compromised,” he adds.
When selecting the battery, the engineering team decided to shun the traditional nickel-metal hydride and lithium-ion batteries favoured by today’s hybrid manufacturers and opt for a novel lithium-ion alternative. Developed by US-based nanotechnology materials manufacturer Altairnano, the lithium-titanate oxide battery, known as ‘NanoSafe’, which uses nanotechnology can be re-charged much more quickly than a standard cell.
“We want to provide a motoring experience where the driver can pull up and fill up,” Dell explains. “These batteries can be charged – from a three-phase supply – to about 70 per cent of their full charge in about four to five minutes and fully charged in around ten minutes. Standard lithium-ion batteries need to be charged overnight, taking six to seven hours.”
What makes this possible is the use of a nano-titanate electrode. While typical lithium-ion cells contain a graphite cathode, swapping this for a nano-titanate electrode speeds recharging and discharging.
Fast charge aside, the batteries can perform at extreme temperatures, from 75°C to -30°C, and are said to be a lot safer than standard lithium-ion cells. As Altairnano researchers say: “The graphite in standard lithium-ion batteries is the catalyst for thermal runaway – an uncontrollable heat-generating reaction – leading to fire and explosion of the battery.”
Altairnano researchers say they have tried overcharging, dropping, crushing and puncturing their nano-size lithium-titanate oxide cells, and still no malfunctions or explosions have occurred.
As well as being safer, Altairnano says its battery actually ‘lasts longer than your car’ – around 20 years – as it can be charged some 25,000 times, with 85 per cent of its charge capacity being retained after 15,000 cycles. In contrast, lithium-ion batteries only perform around 1,000 charges, offering a lifetime of between three and five years, while nickel-metal hydride batteries last around three years.
But Lightning’s innovation doesn’t stop with the body and battery. The vehicle’s engineers are also taking the bold move of housing its drive electronics and motor within each wheel, instead of under the bonnet.
Manufactured by PML Flightlink, UK, the drive system has already been tested on a BMW Mini where each motor can develop some 750Nm of torque enabling fast acceleration and sudden braking. Indeed, PML says its motors will accelerate a 1.5-ton vehicle to 60mph in about 4.5 seconds.
The motors provide regenerative braking at each wheel, Lightning’s only form of braking. Dell says the decision to rely solely on regenerative braking sits well with the company’s choice of Altairnano’s batteries, as these cells can take a large charge over a short time.
“The process throws an awful lot of power at the battery – the vast majority of batteries out there can’t take that level of charge,” he adds.
Dell also favours the mechanical simplicity of using wheel-mounted motors. “We don’t need to use any sort of gear box, all the driving takes place at the wheel.”
But while a wheel-mounted motor offers several vehicle-control advantages, it has been criticised over its weight. Indeed, Dell admits that the weight per wheel is slightly heavier, but says that once the normal braking system and all its associated components are removed, the additional weight per wheel is between 4kg and 5kg. He adds that his team will experiment with using lightweight wheels, such as magnesium hubs with carbon fibre rims, to compensate for this weight gain.
However, this wealth of innovation – Lightning may even have a programmable sound generator to mimic its petrol-driven counterparts – doesn’t come cheap. The price tag of £150,000 means your average boy racer will have to start saving now.
But as Dell insists: “This is not a high price within the market we are operating. Our competitors are the Aston Martin DB9 and Vanquish. In 2003, Aston Martin sold just over 400 cars, whereas now they are selling 2,400 cars, with 2,200 in the UK alone. This certainly shows that there is demand in that market at that price point.”
While Dell could well be right, California-based Tesla Motors has just opened its first showroom in Los Angeles, selling its own version of an electric sports car at a relatively cheap $103,000.
The Tesla Roadster promises 0 to 60mph in 3.9 seconds, with a top speed of 125mph. Unlike Lightning, however, the Tesla Roadster already has 1,000 bookings, including celebrity interest from George Clooney and Matt Damon.
Surely Dell is worried? No, he says, claiming that the Lightning houses more innovative technology, including the fast-charging ‘NanoSafe’ battery. Tesla relies on 6,831 lithium-ion laptop batteries, which it says take between three and four hours to charge.
“We have huge amounts of regenerative braking and the wheel motors give us four-wheel drive,” Dell adds. ”We also know that [Tesla] is looking at more of a mass market.”
Barring overseas competition, is Dell confident his fully-electric sports car, which can reach 60mph in less than four seconds and has a top speed of 130mph, can be a winner?
“The reason for choosing 100 per cent electric is really about building [a car] with no compromises whatsoever, and with a hybrid [petrol-electric] car there are still emissions,” he says.
“Yes, you need a stepping stone toward the all-electric power train, but we want to future-proof our vehicle by going for the ultimate goal of the electric performance sports car.”
Technologists from various disciplines were presented with a range of 21st century ‘grand challenges’ earlier this year when the US National Academy of Engineering (NAE) drew up a hit-list of problems that have arisen from innovations in the last century.
These range from making solar energy more affordable to preventing nuclear terror. E&T is meeting these challenges head on. In coming months we will be publishing a series of in-depth features on a number of these topics, starting in this article with a focus on engineering better medicines. In the next issue we will be looking at enhancing virtual reality: just how real will it get?
You can comment on our Grand Challenge features on the E&T website after they are published (see www.theiet.org/engtechmag). The NAE’s full list can be found at www.engineering challenges.org
Heart disease is the leading cause of death in the Western world and is a prime target for modelling work. This is where Professor Dennis Noble of the Oxford Cardiac Electrophysiology Group and Professor Peter Hunter of the University of Auckland have focused on pioneering work to understand how the heart works.
They have built increasingly detailed computer models of the heart (see right) that can be visualised in 3D to the point where the model can demonstrate phenomena such as heart attacks caused by sudden impacts.
“If you are on a golf course and are unfortunate to be hit in the chest, the energy is enough to change the properties of stress-activated channels in the heart,” Noble explains. “The energy is enough to change the properties of the stress channels and you get a wave chasing its tail around the heart. The result is that you don’t pump enough blood with each beat.”
Techniques to determine how cells work are beginning to pay off in the production of medicines, particularly for those aimed at the developing world where traditional synthetic chemistry is too expensive to be useful.
By reprogramming yeast cells, Professor Jay Keasling of the University of California at Berkeley believes it will be possible to cut dramatically the cost of producing the anti-malarial drug, artemisinin. “It was discovered by the Chinese in 150BC and was then rediscovered in the Vietnam War,” Keasling says. “The problem is its cost. For a traveller from the developed world, a cost of $20 to $40 is no problem. But for the developing world, it is.”
The project is now being brought to the marketplace by pharmaceutical company Sanofi-Aventis as part of a larger project to investigate the feasibility of using yeasts for producing a wide range of biological chemicals. To speed up the process of getting the biologically produced drug to market, the yeasts will produce a precursor, artemisinic acid, rather than artemisinin itself.
“By stopping at artemisinic acid, we can remodel the production in the microbe without going back through [US Federal Drug Adminitration] approval,” Keasling says. The conversion to artemisinin can be carried out cheaply using conventional chemical techniques.
The process involves re-engineering the chemical pathways that take as a feedstock a chemical the cell already has or can make in abundance and then convert it to the desired molecule. The UC Berkeley team found enzymes that could make a series of intermediates that would ultimately produce artemisinic acid and set about replacing others in a target cell using genetic-engineering techniques.
“You can’t put in any old pathway: it takes a lot of troubleshooting,” says Keasling. As with the synthetic systems biology experiments, there are often interactions that appear when the organism is loaded with the new genes. The pathway started to kill the reprogrammed cells, but they found that fatty acids in the growth medium relieved the problem by diverting one part of the altered chemical pathway. However, that would be too expensive in production. So they set about adding in steps that would prevent the build-up of toxins by mutating the organism and letting natural selection pick the survivors.
To improve the production rate, the researchers started joining the enzymes together. Although it is possible to let chemicals diffuse through the cell to find the protein that will convert them into the molecules needed for subsequent stages, this diffusion is slow. “It is like laying down pipes without connecting them. It is a crazy way to build metabolic pathways.”
Nature has evolved some shortcuts by putting enzymes for fast pathways onto a protein ‘scaffold’. “The product of one enzyme does not diffuse through-out the cell, it is linked to another enzyme on the scaffold,” Keasling explains. There was a 70-fold improvement in throughput.
Although there is still a lot to do, the work is delivering insights into the way metabolic pathways function that can feed back into the systems biology work.
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