Fuel Cell Power

This project is for advanced students. We’re going to build a car that runs entirely on sunlight and water.  Use energy from the sun, we’ll first use a solar cell to convert sunlight into electricity.

Then we’ll use that electricity to split the water molecule (H₂O) into hydrogen and oxygen atoms and store them in separate tanks.

Lastly, we’ll flip the system around to allow the hydrogen and oxygen gases to mix, which will produce the power to run the car and create an exhaust product that’s just plain water.

How does that sound?
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We’re going to use solar cells and the basic ideas from Unit 10 (Electricity & Robotics) and Unit 8: Chemistry to build a fuel cell vehicle.  The fuel cell is reversible, meaning that you can use it to pull apart water molecules into atomic gases, or combine the atomic gases together to make water.

You’ll need to order the Fuel Cell Car Kit (Item# KT-FUELCCK from www.hometrainingtools.com). This kit is a bit expensive, but if you want to build a car that runs entirely from sunlight and water, this is the one you want to get.  The company that makes this particular model also sells the conversion kits for (real!) cars.

Here’s what you do:

How does that work? Molecules can also be split chemically, or by getting hit by a fast-moving particle. When you recombine the hydrogen and oxygen, energy is produced – enough to power a small car. If you guessed that this has to do with Unit 10: Electricity and Unit 8: Chemistry, you’re right! But you might wonder how they work together.

Back in 1800, William Nicholson and Johann Ritter were the first ones to split water into hydrogen and oxygen using electrolysis. (Soon afterward, Ritter went on to figure out electroplating.) They added energy in the form of an electric current into a cup of water and captured the bubbles forming into two separate cups, one for hydrogen and other for oxygen.

It takes energy to split a water molecule. (On the flip side, when you combine oxygen and hydrogen together, it makes water and a puff of energy. That’s what a fuel cell does.)

Back to splitting the water molecule – as the electricity zips through your wires, the water molecule breaks apart into smaller pieces: hydrogen ions (positively charged hydrogen) and oxygen ions (negatively charged oxygen). Remember that a battery has a plus and a minus charge to it, and that positive and negative attract each other.

So, the positive hydrogen ions zip over to the negative terminal and form tiny bubbles right on the wire. Same thing happens on the positive battery wire. After a bit of time, the ions form a larger gas bubble.

If you stick a cup over each wire, you can capture the bubbles and when you’re ready, ignite each to verify which is which. We covered the basics of electrolysis in Unit 8, and now we’re going to show you how to store the energy and use it power a small car in our fuel cell project together.

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