They started under clear skies and blazing heat and finished in steady rain, but the winner of the 2011 World Solar Challenge has been decided. After 4 days of travelling, Tokai University (Japan) crossed the finishing line north of Adelaide today in the lead.
In the closest finish in the history of the WSC, mere minutes separated Tokai and second placed Nuon Solar Team from the Netherlands. Third placegetters University of Michigan (USA) were themselves only a short distance behind. The close finish is remarkable given the distance travelled and time spent on the road. Ashiya University, of Japan, and Team Twente, also of the Netherlands, are further behind vying for fourth place and expected to finish Friday, as is Team Aurora of Australia, not far behind Ashiya and Twente.
The World Solar Challenge is an epic 3000km solar car challenge, running down the length of Australia from Darwin to Adelaide. With unlimited regulations it is likely all the cars would be able to exceed the road speed limit and run for extended periods of time. Instead, the regulations deliberately limit battery sizes and solar collection area to prevent the ability for the cars to run at maximum speed for hours on end and hence to help promote the development of more efficient solar collector units and motors.
The main differentiator between the cars is the ability of the solar cells to collect energy from the sun and convert it into electricity. With limited battery sizes, the energy which can be held on board the car isn’t enough to allow unrestricted running. Instead, the speed of the car is dictated by the combination of the amount of energy being collected from the solar panels, and the efficiency of the motor using that energy. The faster a car runs, the more energy it uses and hence the more energy it needs to collect to replace that used. Quite simply, if a car’s solar panels aren’t efficient in collecting energy to replace that being used, the car will run out of electricity. So a balance needs to be found between energy collection and expenditure, with cars more efficient at collecting and using energy able to run at higher speeds.
Further adding to the challenge, running of the cars is restricted to certain hours of the day, with cars required to hold at positions overnight. To ensure that the cars do maintain these hold positions, and stay within the legal speed limits, a sophisticated tracking system is employed to monitor the progress of each team. This ‘Mission Control’ was this year based in the Science Exchange in Adelaide.
This year’s race was never going to break any records with the challenge suspended for several hours due to bushfires close to the race route. There was also another dramatic development on day 4 when a car from Team Philippines, having been parked for repairs to its battery system, suffered an explosion in its battery packs. Thankfully, no one was injured.
Another challenge faced by the teams competing in the World Solar Challenge are the outsized road trains which Australian highways are famous for. These extremely long and wide trucks normally require traffic coming the other way to pull off the highway to allow the truck to pass. However, according to Bruno Moorthamers from Nuon in an interview with The Register, a solar car’s steering doesn’t allow this manoeuvre. Instead, Bruno said he has to drive “a little under” the overhanging loads of the trucks.
Despite crossing the official finishing line Thursday afternoon, a late developing fault meant that Nuon would not enter Adelaide city until the following day, meaning that celebrations in the Victoria Square ceremonial finishing line were reserved for Tokai. Dutch supporter groups hoping to cheer home Nuon and Twente were left instead to congratulate the victorious team and wait for their teams to arrive on the Friday. Tokai certainly celebrated in the rain, and definitely showed their excitement at having won such a hard-fought challenge.