Cement has a carbon problem. Here are some concrete solutions

The biggest carbon polluters don’t always advertise that fact loudly. In fact, one of the industries with the worst climate impact is all but ignored, even though its product literally supports our existence. I’m talking about the cement industry, which dumps more than 2 billion tons of carbon into the air each year to make its ubiquitous building material, roughly three times as much as the aviation industry.

What accounts for that jaw-dropping carbon footprint? To make cement, you have to heat limestone to nearly 1,500 degrees C. Unfortunately, the most efficient way to get a cement kiln that hot is to burn lots of coal, which, along with other fossil fuel energy sources, accounts for 40 percent of the industry’s emissions. Eventually, the limestone breaks down into calcium oxide (also known as lime) and releases CO2, which goes straight into the atmosphere, accounting for a further 60 percent of the industry’s emissions.

The good news is that there’s no shortage of ideas for how to slim down cement’s weighty carbon footprint. The bad news is that most of them are either in their infancy or face significant barriers to adoption. As our window of time for preventing catastrophic climate change grows ever smaller, we need major investments in new technologies and changes to how the cement industry works. But most of all, we need politicians need to wake up to the fact that the cement industry has a climate problem. It’s time for some concrete solutions.

 
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