Ammonia rarely makes headlines, but much of modern life depends on it. The compound of nitrogen and hydrogen is the key ingredient in the fertilizers that help feed roughly half of the world’s population. It is also attracting serious attention as a carbon-free fuel for ships, power plants and heavy industry.

The problem is how we make it. Nearly all of the world’s ammonia comes from the Haber-Bosch process, a century-old technology that forces the nitrogen from air and hydrogen together at temperatures of 400 to 500 C and pressures more than 200 times that of the atmosphere.

It works remarkably well, but it is also energy intensive. The process consumes about two per cent of the world’s energy supply and produces between one and two per cent of global carbon dioxide emissions.

Our research at McMaster University points to a different path: using renewable electricity to turn nitrate, one of the most common water pollutants, directly into ammonia.

In our recently published study, we showed how carefully designed iron-based catalysts can make this conversion more efficient. The approach tackles two environmental problems at once. It removes a harmful pollutant from water and produces a chemical the world urgently needs.

The timing matters. The International Renewable Energy Agency projects that global........

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