Splitting water to make cement could clean up a dirty industry

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Action on climate change has been focused on the electrical grid and our transportation systems, but there are other hurdles between here and a zero-greenhouse-gas-emissions world. Agriculture and deforestation are major hurdles, but so is cement.

Producing this humble, gray, ubiquitous building material actually accounts for about 8% of global CO₂ emissions. Firing the kilns required for this process is very energy intensive, but the process itself also releases CO₂ from its starting materials. The primary ingredient in concrete is calcium oxide, which is taken from limestone (CaCO₃)-and that leaves CO₂ as a byproduct.

That means there are two problems to solve: the cement-making process needs to run on clean energy, and the CO₂ that is released must be captured somehow. A new study led by MIT's Leah Ellis outlines an option that could make progress on both.

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