How Do Fuel Cells Work?

Mark Snyder
Do It Green! Minnesota

In recent years, you may have seen news items about fuel cells and the coming “hydrogen economy” and wondered what exactly is a fuel cell? A fuel cell is a form of a reactor where we can create electricity through an electrochemical reaction of hydrogen and oxygen. The only by-products of a hydrogen-fueled fuel cell are pure water (H2O) and heat.

In a fuel cell, when hydrogen (H) and oxygen (O) atoms come together to form water, two electrons are released and it’s these electrons that make up an electric current. Although types of fuel cells may differ in the molecular form of the hydrogen and oxygen used to accomplish it, this basic, natural reaction is used in all fuel cells to make water and electricity.

Since most of our electricity in Minnesota comes from coal, there are a lot more by-products involved than just water and some heat. There are greenhouse gases such as carbon dioxide; nitrogen oxides, which contribute to smog; and sulfur oxides, which contribute to acid rain; and finally, toxic metals such as mercury which in turn can affect our lakes and fish.

But what about wind or solar? These are sources of electricity that do not create the above-mentioned by-products, either. However, these resources are also considered to be “intermittent,” meaning they are not available when the sun is not shining or the wind is not blowing. Hydrogen and fuel cells offer a way to help get around that problem. We can use some of the energy we get from wind or solar to make hydrogen from water — this is known as hydrolysis. This process allows us to “store” solar or wind energy in the form of hydrogen and then generate electricity from our stored hydrogen using a fuel cell.

Storing wind and solar energy for later use would offer us the opportunity to make sure the “hydrogen economy” we get is built on a foundation of renewable energy resources and not just more dependence on fossil fuels or nuclear energy.

Fuel Cells

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