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Fuel cells in space: what the space program proved

When engineers needed reliable power and water in a sealed capsule far from Earth, they turned to hydrogen fuel cells.

Why spacecraft used them

Early crewed spacecraft needed electricity for days at a time, and batteries heavy enough to supply that were impractical. Engines were out of the question. Fuel cells combined stored hydrogen and oxygen to make electricity steadily, and the by-product was pure water the crew could drink. The American Gemini missions used early PEM fuel cells, and the Apollo spacecraft used alkaline fuel cells, as did the later Space Shuttle.

What it would keep running

  • Steady power with no refuelling
  • Water returned to the loop
  • Quiet power with no engine
  • Hydrogen made on site from water
  • Oxygen drawn from ordinary air

What carried over

The core lesson was that fuel cells can deliver steady, quiet power in places where refuelling is impossible and combustion is a bad idea. That maps neatly onto an isolated rural house during a week-long outage. The PEM technology first flown in space has been developed for decades since, becoming more durable and practical.

Another lesson was water. In space, water from the fuel cell was precious. In this system, water from the fuel cell is captured and returned to the loop for the electrolyser, which matters on properties that rely on tank water.

How it works →
The H2OME loop: an electrolyser splits water into hydrogen, the hydrogen is stored in a tank for weeks, a fuel cell turns it into electricity for your home, and the water returns to the loop.

What is different at home

Spacecraft carried hydrogen and oxygen as cryogenic liquids, loaded before launch, and cost was no object. A home system makes its own hydrogen from water and electricity, stores it as a gas at 30 bar or less, and takes oxygen from the air. It has to be affordable, serviceable and safe beside a family home for years. That is a different engineering challenge, and why it is still in development.

Questions

Did astronauts really drink fuel cell water?

Yes. Water produced by the fuel cells on crewed spacecraft was used by the crews. In this home system the water goes back to the electrolyser loop rather than to your taps.

Is a home fuel cell the same as the space ones?

It shares the basic principle, and PEM technology is a direct descendant of early space work. Materials, durability and cost have changed greatly since, and a home system draws oxygen from air rather than a stored tank.

Did space fuel cells ever fail?

Spacecraft power systems had faults over the years, and the space program learned hard lessons about oxygen tanks and pressure vessels. That history is one reason careful design, low pressure and leak monitoring matter in this system.

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