Fuel Cell Car

Perhaps the biggest challenge facing scientists today is environmentally sustainable energy. That is, energy must be produced without damaging local air quality or causing global climate change. Can hydrogen fuel cells get us there? Maybe, but there is lots to be done before we can declare victory. Key questions are Where would the hydrogen come from and how would we use it effectively?

Researchers at Honda America are working to create the gas station of the future - a place where hydrogen fuel is made by splitting water molecules using energy from solar panels. Sossina Haile, Associate Professor of Materials Science and Chemical Engineering at the California Institute of Technology, explains "Solar energy comes in, hitting photo-voltaics to generate electricity; that electricity is then used to split water, giving hydrogen and oxygen. The hydrogen can be thought of as a portable form of solar power, which can be used when it is needed (rather than just when the sun is shining)." The hydrogen is pumped into the tank of the car just like gasoline would be pumped, but the hydrogen fuel is used in a fuel cell that runs the car rather than a conventional combustion engine.

Scientists at Caltech are doing the basic materials research necessary to transform fuel cells from laboratory curiosities into widely accepted technological devices. What a fuel cell does is extract the chemical energy of hydrogen and directly convert it to electricity (to power, for example, an electrical motor in a car). A hydrogen fuel cell is made up of three primary components - the proton conducting membrane, the anode, and the cathode. During operation, hydrogen fuel is brought into the anode chamber of the fuel cell and oxygen to the cathode chamber [needs a figure!]. The two chambers are separated from one another by the membrane, which allows protons to move across it but not the gases. Because the hydrogen would end up in a lower energy state by reacting with the oxygen to make water, there is a driving force in the system for the hydrogen to move across the membrane over to the cathode side. The only way this can happen is for the hydrogen gas (H2) to drop off its electrons (e-) at the anode and turn into protons (H+), which can get across the membrane. At the cathode side, the protons pick up electrons and react with oxygen gas (O2) to form water (H2O). This means that the electrons that are dropped off at the anode travel through an exterior path (say again through an electric motor) to get to the cathode, and this is how the electricity is generated.

“A fuel cell combines the best of batteries with the best of combustion engines,” says Haile. This is because the electrochemical reactions are clean (a lot like a battery), producing only pure water as a by-product, but the power source is refueled (like an engine) rather than being recharged.

The 80-kilowatt fuel cell engine in the Honda [car name] is equivalent in power to about a 100 horse-power combustion engine – a typical four-cylinder car. Driving a fuel cell car feels a lot like driving a standard car, but with a few key perks: they are very quite because there is no combustion going on, the electric motor has a lot of torque (so for the first few milliseconds you could beat a Ferrari in a race), and the exhaust is clean enough to drink!