The electrical prototype of the Polyjoule team is the most energy efficient vehicle in the world. During the EducEco Challenge competition (from May 2-4, 2012), on the Nogaro circuit in Gers, France, the all electrical prototype of Polyjoule got the result of 10,017 km with the energy equivalent of 1 liter (a bit less than a third of a gallon) of oil.
The context of this competition is the same as that of Shell* Eco-marathon. The aim is to do a given number of laps, with an average speed of 30km/h (19 mph), and to use a minimum of energy! Our prototype was powered by a battery which allowed the electrical engine to spin the wheel. At the end of the race the jury measures the quantity of energy we used… Thus, with the energy of one liter of oil, we would have covered 10,017 km (6,224 miles)!
In other words, for those who are scientists, our prototype is able to cover 1136km (706 miles) with one kWh. That is 35 percent above the Eco-marathon world record (843kWh/km).
All right, 67 Euro ($86) for a return trip from Earth to the Moon is a striking figure, but what is the secret of the Polyjoule team? The answer is not found in a technical aspect, but in the human aspect of passion.
Let’s move backward, 30 years ago. Philippe Maindru is a fresh new engineer in mechanical automobiles who always wanted to teach. He finds his place in the technical school La Joliverie, in Saint-Sébastien-sur-Loire, France, and with other new engineers they form an over-motivated pedagogic team. This is at this moment that the elder brother of Polyjoule, Microjoule, was born. We are in 1985 when the first Microjoule thermal engine prototype, named Le P’tit Joule, went to Eco marathon.
The first result sounds promising: 400 km (249 miles) with one liter of fuel. At this moment it is already a world record… This is the start of a great adventure: every year more and more students and professionals are involved in the project. The work is colossal; sometimes students and professionals are working till midnight, but the technical challenge and the thrill of the competition motivate the team most of all. This energetic excellence is nothing but a work on each detail of the prototype. This requires a complete knowledge of the mechanics and of the physical phenomena (friction, aerodynamics, combustion etc.). Everywhere we were able to save a watt of energy, we saved it!
Thus the race for the economical mobility is on. In 25 years, across the circuits of Castellet, (France), Silverstone (UK), Rockingham (UK), Suzuka (Japan), and Lausitz (Germany), Microjoule won 35 first places and seven world records. Before each competition the topology of the circuit is studied so as to build the race strategy: the fundamental question is “which speed and where?” This way, year after year, Microjoule gets a unique know-how.
In 2003 the Microjoule fever was about to spread to a new school: the engineering school Polytech Nantes. Jean-Charles Boulerie, who was a student in the technical school La Joliverie and was involved in Microjoule, enters in Polytech Nantes. He suggests that we should duplicate prototype Microjoule, and replace the thermal engine with a fuel cell stack. This way we could benefit with the perfect mechanics and use a cleaner propulsion system. The Polyjoule project was born. Now it is three main centers which are working together: the Electronic and Thermal (hydrogen) centre in Polytech Nantes, and the Mechanics centre in La Joliverie. Once again the synergy leads to success: 3 first places at Eco marathon in the hydrogen prototype category since 2005. Our key figure was established in 2011 on the Lausitz circuit with 5136 km (3191 miles) with the equivalent energy of one liter of oil.
This year the Polyjoule prototype participated for the first time in competition before Eco-marathon so as to prepare the pilot, Marie Maille. That is the reason why we decided to simply power our prototype with a battery instead of our fuel cell stack. This way the system is simpler and we could focus on the strategy and get experience for Eco-marathon.
At the end of this prior competition, our pilot was ready and the mechanics and electric circuitry were tested. This was a really important stage before Eco-marathon, which relocated this year in Rotterdam, Netherlands, with a more complex circuit!
This week we prepared the last technical aspects and focused on the race strategy. The Eco adventure will start on Monday for a competition from May, 17 to 19!
*Shell is sponsor of the Great Energy Challenge initiative. National Geographic retains autonomy over content.