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Renault has unveiled its Scenic ZEV H2 prototype car. Powered by a fuel cell, the ZEV H2 emits only water vapour.
Derived from Grand Scénic, the ZEV H2 is a joint Alliance project with Nissan. Nissan has supplied the fuel cells stack, the high-pressure hydrogen tank, and lithium-ion batteries. Renault’s engineers have repackaged the Grand Scénic so that its underbody can incorporate the fuel stack, tank and batteries. They have redesigned the floor and raised the vehicle’s ground clearance by a further 60 mm. They have also managed to keep the vehicle’s initial spaciousness (five adult seats), which is a first in fuel cell prototypes.
The Scenic ZEV H2 car has a silent engine and responsive acceleration which combines with smooth handling on a par with European standards. Driven by an electric motor, Scenic ZEV H2 fully embodies the driving sensation associated with EVs, the only difference being that there is an additional fuel stack on board.
In 2006, Renault and Nissan decided to pool their efforts to produce a demonstration vehicle powered by a fuel cell that drew on Alliance technologies. Scenic ZEV H2 was designed in just 15 months, testing included. Once the detailed engineering had been completed, assembly work on the first vehicle kicked off in France in the summer of 2007. At the end of September 2007, the French and Japanese partners met to carry out a joint check. Its aim was to be sure that both Renault and Nissan components fitted with vehicle design in accordance with computer calculations. The first prototype was then transferred to Japan for final assembly. At the end of 2007, the first vehicle was on the road. The project reached completion at the end of April 2008 once all fine-tuning had been finalised.
Made up of a nucleus and a single electron, hydrogen is the simplest and lightest of chemical elements: it is 14 times lighter than air. Its freezing point is -259.14°C and its boiling point is 252.87°C. In a fuel cell, hydrogen and oxygen are forced into contact with each through a polymer membrane, the electrolyte. They combine to form water (Scenic ZEV H2’s only ’emission’) to produce electric power and heat. This electric energy is the fuel that drives the vehicle’s electric motor.
A fuel cell vehicle is in fact just an electric vehicle that produces its own electricity on-board and does not necessarily require any external power supply.
The fuel cell system that powers the demonstration vehicles comprise five main sub-assemblies: the hydrogen tank which supplies fuel to the stack, power electronics in conjunction with a regulator which interfaces between the stack and electric motor, and lithium-ion batteries.
The vehicle can operate in five main modes thanks to its hybridized power system:
• The battery alone supplies power directly to the electric motor. This power supply mode operates when the vehicles starts, when parking, or when driving in the city. It also kicks in when the car accelerates sharply, as the battery can deliver bursts of high power to complement the fuel stack.
• The fuel stack alone supplies power to the electric motor. The vehicle generally uses this mode when travelling at a steady speed, e.g. on a motorway. Power not used by the electric motor is directed to the battery.
• The stack and the battery deliver power to the electric motor when the vehicle’s requires an extra power boost, e.g. up a long gradient or when overtaking at speed.
• When the vehicle is at a standstill with its engine running, the electricity produced by the stack is used to recharge the battery.
• When the vehicle is decelerating, the electric motor feeds the power battery, acting as a generator. The fuel stack can also recharge the battery.
The Renault-Nissan Alliance’s longer-term outlook focuses on continuing work on EV prototypes powered by fuel cells. Though they offer significant gains in range they are more complex to mass-produce and mass-market. Rolling out such breakthrough technology requires production, transportation, and distribution infrastructure – there are less than 300 filling stations worldwide in 2008. A further requirement is reducing the cost price of fuel cells, particularly by using less precious metal.
Renault announced in 2006 that it would test vehicles powered by fuel cells as part of the Renault Commitment 2009 growth plan.
With regard to other environmental initiatives, in May 2007 Renault introduced its Renault eco² label – a system for badging its vehicles so that customers can identify the most environmentally friendly versions.
In November 2007, Renault entered an eco²-labelled Logan Concept in the Michelin-organised Challenge Bibendum, demonstrating that a car could be both ‘ecological and economical’ without stinting on performance or equipment.
Renault has maintained its commitment with the unveiling of TCe 130, Powertrain Engineering’s latest innovation in downsized engines.
Renault’s efforts have made it one of Europe’s three most carbon-efficient car manufacturers. Its achievements in CO2 reduction are important, but it considers that it is just as critical to curb pollutant emissions with initiatives such as the NOx Trap.
Renault has continued its strategy of developing an electric vehicle (EV) . In January 2008, the Renault-Nissan Alliance signed an agreement with Project Better Place to mass-market EVs in Israel and Denmark by 2011. Other markets could follow soon after.
