We already had spoken about the fuel cell technology (borrowed from Nissan) installed in a plain Renault Scénic, one of Europe's most popular compact minivans. The interesting part of the concept, at least from the aesthetic point of view, is that the car's interior room remained untouched, thanks to sandwhiching most of the components in the floor of the vehicle.
Like other fuel cell vehicles, the fuel-cell Scénic ZEV H2 features a hybrid powertrain. The system includes lithium-ion batteries that, together with the high-pressure tanks, allow the car to have a 220-mile range. The 350-bar hydrogen tank (3.7kg of H 2) will be substituted by a 700 bar tank at a later date, which would allow a range of more than 300 miles.
Find the full press release after the jump.
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.
Derived from Grand Scénic, the ZEV H2 is a joint Alliance project. Nissan has supplied the fuel cells stack, the high-pressure hydrogen tank, and lithium-ion batteries. Renault's engineers have repackaged 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.
Renault's Vehicle Engineering have also incorporated Renault's and Nissan's electric and electronic systems. The fuel cell in itself is a relatively self-sufficient electronic system which was designed by Nissan to communicate with vehicle components and features like the dashboard, ABS/ESP, climate control, and airbags. All perform to the maximum of their original capacity.
Some instrumentation, however, has been adapted to the vehicle's new drivetrain. The fuel gauge, for example, is now a hydrogen pressure indicator, while the temperature display shows the fuel's temperature, and the rev counter displays the electric motor's revolutions per minute.
Scenic ZEV H2 is also a vehicle that boasts unrivalled driveability. Its silent engine and lively, responsive acceleration combine with particularly 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 (see 'Hydrogen and fuel cells').
Although a prototype, Scenic ZEV H2 has all the qualities of a 'real' car. The levels of travelling comfort and performance it affords make it perfectly well suited to everyday use. And it emits nothing more harmful than water vapour.
The Scenic ZEV H2 project
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.
Hydrogen and fuel cells
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.
SCENIC ZEV H2: TECHNICAL CHARACTERISTICS
* A single, powerful electric motor developing 122hp
* Lithium-ion battery, operating at a voltage of around 400V and delivering a power output of 25kW.
* A fuel cell using compressed hydrogen gas at 350 bar.
* Optimised hydrogen consumption: brake energy regeneration and storage of energy in the battery which feeds it back as required.
* Top speed of 100mph
* Acceleration from standstill to 62.5mph in 14.6 seconds.
* Range: approximately 220 miles with a 350 bar hydrogen tank (3.7kg of H2). The plan is to use a 700 bar tank at a later date, which would ensure a range of more than 300 miles
* Outstanding acoustic comfort: the motor produces no noise; the only sound is that of road noise at low speeds and wind noise at higher speeds.
* Identical cabin space: the same cabin space for occupants as that of the current Scenic.
* Easy to use: the same dashboard as the production car. The only differences concern the display of additional information relating to the hydrogen (e.g. the rev-counter displays the speed of the electric motor, while the Energy Display is incorporated in the Renault navigation system display).
* Weight: 1,850kg (Scenic 1.9 dCi: 1,550kg).
How the vehicle operates:
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.