Massachusetts Institute of Technology (MIT) researchers have demonstrated an experimental way of manufacturing cement that releases no carbon dioxide into the atmosphere.
Currently, the production of cement for concrete accounts for about eight per cent of global greenhouse gas emissions, leading to calls for architects to stop using it.
However MIT's materials scientists are exploring compromise solutions, including one that they consider "an important first step" towards more sustainable cement.
Their process incorporates an electrochemical method that means that, although carbon dioxide is still produced, it is able to be cleanly captured, so that no emissions enter the environment.
Process captures carbon dioxide emissions  A team led by MIT engineer Yet-Ming Chiang team tackled the problem of carbon dioxide emissions at the two points in the cement manufacturing process where they arise: from the burning of coal to create the necessary high heats, and from the gases released during the resulting chemical reaction.
Tackling the first source of CO2 was simply a matter of using electricity from renewable sources ? sources that they note are increasingly the lowest-cost option.
The second source of CO2 involved a more novel approach of using an electrolyser to convert the limestone's calcium carbonate into calcium hydroxide.
Captured CO2 could be used to make fizzy drinks
With this change, the CO2 comes out as a concentrated gas stream that can be easily separ...