Visit Your Local PBS Station PBS Home PBS Home Programs A-Z TV Schedules Watch Video Donate Shop PBS Search PBS
NOVA scienceNOWNOVA scienceNOWNOVA scienceNOWComing up
arrow Fuel Cells
Clickable Fuel Cell Car

Clickable Fuel Cell Car

See interactive version

Fuel cell car

Fuel Cell Stacks
Enlarge this image


Fuel Cell Stacks
This is the heart of the hydrogen fuel cell car—the fuel cell stacks. Their maximum output is 86 kilowatts, or about 107 HP. Because hydrogen fuel cell stacks produce power without combustion, they can be up to twice as efficient as internal combustion engines. They also produce zero carbon dioxide and other pollutants. For more information on the stacks, see How Fuel Cells Work.


fuel cell cooling system
Enlarge this image


Fuel Cell Cooling System
This has several parts. Perched at an angle at the front of the vehicle is a large radiator for the fuel cell system, while two radiators for the motor and transmission lie ahead of the front wheels below the headlights. The car also has a cooling pump located near the fuel cell stacks to stabilize temperature within the stacks.


ultracapacitor
Enlarge this image


Ultracapacitor
This unit serves as a supplementary power source to the fuel cell stack. Like a large battery, the ultracapacitor recovers and stores energy generated during deceleration and braking. It uses this energy to provide a "power assist" during startup and acceleration.


hydrogen tanks
Enlarge this image


Hydrogen Tanks
Space in a car is limited, yet hydrogen is the most dispersive element in the universe and normally requires lots of room. A challenge for manufacturers is how to compress the gas into tanks small enough to fit in a compact car and yet still provide enough fuel for hundreds of miles of driving between refuelings. The two high-pressure hydrogen tanks in this vehicle can hold up to 3.75 kilograms of hydrogen compressed to roughly 5,000 PSI—enough to enable an EPA-rated 190 miles of driving before refueling, the manufacturer says.


electric motor
Enlarge this image


Electric Motor
(General area only—motor not visible) The electric motor offers a maximum output of 80 kilowatts, enabling a top speed of about 93 miles per hour. The manufacturer says this vehicle can also start in subfreezing temperatures (down to about -4°F), a perennial problem in fuel cell prototypes. Being electric, the engine and the car as a whole are quiet, with none of the vibration or exhaust noise of a gas-powered automobile.


air pump
Enlarge this image


Air Pump
(General area only—air pump not visible) Run by a high-voltage electric motor, this pump supplies air at the appropriate pressure and flow rate to the fuel cell stacks. The air, in turn, mixes with the stored hydrogen to create electricity.


air pump
Enlarge this image


Humidifier
The humidifier monitors and maintains the level of humidity that the fuel cell stack needs to achieve peak operating efficiency. It does this by recovering some of the water from the electrochemical reaction that occurs within the fuel cell stack and recycling it for use in humidification.


power control unit
Enlarge this image


Power Control Unit
(General area only—power control unit not visible) This controls the vehicle's electrical systems, including the air and cooling pumps as well as output from the fuel cell stacks, electric motor, and ultracapacitor.


cabin
Enlarge this image


Cabin
With the fuel cell stacks hidden beneath the floor and the hydrogen tanks and the ultracapacitor beneath and behind the rear seats, respectively, the four-passenger cabin is isolated from all hydrogen and high-voltage lines. Hydrogen gas is colorless and odorless, and it burns almost invisibly. In case of a leak, therefore, the manufacturer has placed hydrogen sensors throughout the vehicle to provide warning and automatic gas shut-off. Also, in the event of a collision, the electrical source power line shuts down.


hydrogen filler mouth
Enlarge this image


Hydrogen Filler Mouth
(Not visible—located on other side of vehicle) Drivers would fill the car with hydrogen just as they do with gasoline, through an opening on the side of the vehicle. The main difference is that a fuel cell car must be grounded before fueling to rid the car of hazardous static electricity. For this reason, this model has two side-by-side openings, with the latch to open the hydrogen filler mouth located inside the opening for the grounding wire. The manufacturer says filling up this model's two tanks at a hydrogen filling station would take about three minutes.


Note
Enlarge this image


Note
The limited-production vehicle seen in this feature is a Honda 2005 FCX, which is typical of the kinds of hydrogen fuel cell automobiles that some major automakers are now researching and developing. With such vehicles at present costing about $1 million apiece, none is currently for sale, though hundreds of fuel cell cars are now undergoing tests on the world's roads.



Support provided by

For new content
visit the redesigned
NOVA site