An anonymous reader shares a report: The most astonishing thing about cement is how much air pollution it produces. Manufacturing the stone-like building material is responsible for 7% of global carbon dioxide emissions, more than what comes from all the trucks in the world. And with that in mind, it’s surprising that leading cement makers from LafargeHolcim in Switzerland to Votorantim Cimentos in Brazil are finding customers slow to embrace a greener alternative. Their story highlights the difficulties of taking greenhouse gases out of buildings, roads and bridges. After wresting deep cuts from the energy industry, policymakers looking to extend the fight against global warming are increasingly focusing on construction materials and practices as a place to make further reductions. The companies are working on solutions, but buyers are reluctant to pay more.
While architects and developers concentrate on the energy used by their buildings, it’s actually the materials supporting the structure that embody the biggest share of its lifetime carbon footprint. Cement’s contribution to emissions is especially immense because of the chemical process required to make it. About two-thirds of the polluting gases that come from cement production stem from burning limestone. Kilns are heated to more than 1,400 degrees Celsius (2,600 Fahrenheit), about four times hotter than a home oven set to the self-clean cycle. Inside the kiln, carbon trapped in the limestone combines with oxygen and is released as CO2, the most abundant greenhouse gas.