As global warming begins to more strongly influence policy and economic decisions, attention is turning to the construction industry and its massive, 3 trillion kg/annually cement addiction.
The cement industry is the second largest emitter of greenhouse gases, surpassed only by fossil fuel energy sources. Five to six percent of all carbon emissions come from cement production, which can release up to 9kg of CO2 for every 10kg of cement produced.
A team at George Washington University in Ashburn, Virginia, however, have developed a new system of cement production, dubbed STEP, that creates no carbon byproducts, and could be significantly cheaper than existing modes of production.
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The researchers eliminate greenhouse gases released by cement manufacturing on two fronts. Most carbon emissions occur during the decarbonation phase, where limestone is converted into lime via intense temperatures. First, scientists replace existing fossil-fuel powered kilns with solar thermal energy, applied directly to the limestone and also used to assist in electrolysis. The electrolysis, in turn, does not create CO2 as a byproduct, as in traditional methods.
In temperatures above 800 degrees, the process does produce carbon monoxide, which has a range of uses in various industries, such as the formation of plastics. By selling this carbon monoxide byproduct, the cost of creating lime from limestone can not only be offset, but profited from, bringing down the price of cement below current levels.
Scientists say the STEP process can be used in a variety of other manufacturing settings, such as the production of glass, paper, sugar, etc. The solar-powered process can even be continued through the night with molten salt thermal energy storage techniques. The main hurdle now is to scale up the system for mass-production. Off-setting more than 5 percent of global carbon emissions with one fell-swoop, however, may be enough to motivate this entrenched industry to adopt greener practices.