Solar Impulse might have stolen this year’s headlines for solar-powered transport, however a 60-strong team of engineers at Cambridge University is aiming to match the aircraft’s successful summer.
This October the Cambridge University Eco Racing team will take its solar-fuelled car to Australia to compete in the Bridgestone World Solar Challenge, a 3,000km road race from Australia’s northern city of Darwin to the country’s southern tip in Adelaide. More than 50 teams will compete, and the fact that only 10 to 15 are expected to finish is a testament to just how tough the event will be.
Its difficulty is not lost on the Cambridge team. The university’s last entry was in 2013 and despite hopes of a strong challenge, the car was withdrawn before the race had even started due to a number of technical issues, not least its balance and drivability. Alan Jamieson, one of the team’s drivers, says the team had defied all expectations just to get the 2013 entry – named Resolution – to Australia. “It was completely different to anything that had gone before; it was smaller, lighter, with an efficient array of solar cells that could position themselves towards the sun. It attracted a lot of attention,” he says.
An accident in testing ultimately put paid to CUER’s hopes of starting the race. Event organisers deemed it unable to compete after testing and Jamieson says the disappointment caused many of the team to move on.
But CUER is back for 2015 and considerably more confident of completing the race this year. It now has its first full-time programme director in Aurelia Hibbert courtesy of funding by BNY Mellon, who says the team has learnt from its previous faults. Each year the team would suffer what Hibbert calls a “brain drain” as students in their final year who make up the team graduate, but more is now being done to ensure their knowledge and experience is not lost and a number of alumni now feature.
The new vehicle – Evolution – is the result of two year’s rebuilding. The car is now slightly bigger but at no loss to the aerodynamics, while the slightly lower centre of gravity has improved its ‘go-kart like’ handling. The team has also worked extensively with its manufacturing partners Jaguar Land Rover, Marshall Group, Penso, Timeless Green and Viridian Solar to improve various other facets of the vehicle.
The car’s space grade Gallium Arsenic solar array claims to be among the most efficient in the world. It covers 2.36 square metres and is capable of generating up to 750W of electricity, roughly three times that of the average residential rooftop panel. Learning from previous designs, the panel has also been rotated 90 degrees to reduce the shading caused by Fresnel losses in the protective canopy, and it can also orientate itself according to the trajectory of the sun for maximum efficiency. Ventilation towards the bottom of the car will keep the panel – and driver – crucially cool in the Australian desert heat.
Energy generated is stored in a super lightweight lithium battery located beneath the panel which the team says has the best energy density available on the market today, while a redesign of the onboard electrical system has reduced the car’s base vehicle consumption by 15%. Most recent estimates put the battery’s range at roughly 500km. A top speed of 110km/h can be reached, however the car is expected to race safely at between 70 – 75km/h for maximum efficiency.
While lessons learned from previous races have undoubtedly shaped it, and Evolution certainly bears a striking resemblance to its predecessor, the new car drives completely differently and has given the team renewed optimism that they can put 2013 behind them. At a launch event held earlier this week Hibbert said the team felt it was in the “best position ever” for the race and that the “clear difference in manufacturing capabilities” within the team had helped produce a much stronger effort.
The race will be a hotly contested affair featuring well established teams from famous institutes such as MIT, Stanford and the Beijing Institute of Technology. CUER’s only aim is to complete the race, something which Hibbert says would constitute a significant success for the team and represent real progress. By the time the next race rolls around in 2017, Cambridge could be well placed to set their sights a little higher.