Cement production is the second largest human-caused contribution of CO2 to the atmosphere responsible for five to six percent of all human-caused CO2 emissions. So far, many researchers have concentrated on creating cement that can sequester CO2 to balance out the CO2 its production releases, but now researchers at George Washington University are going to the root of the problem and eliminating CO2 emissions at the source.
The researchers have found a way to use solar thermal heating to create a method of cement production that has zero CO2 emissions. The release of CO2 during cement production is in two key places: first is when limestone is converted into lime, which involves decarbonation and releases CO2 as a byproduct; second is from burning fossil fuels to heat the kiln reactors that allow that chemical reaction to occur.
The team's Solar Thermal Electrochemical Production (STEP) process eliminates CO2 from both of those places. Solar thermal heating replaces the burning of fossil fuels and the heat also is essential in the electrolysis of the limestone. Using electrolysis to convert limestone into lime creates a byproduct of either oxygen and graphite or carbon monoxide, not CO2.
The STEP process would also be cheaper than the existing cement production process and if the carbon monoxide byproduct were sold to other industries, it would actually create a net positive of $298 per ton compared to the cost of $70 per ton for conventional production.
The researcher say the STEP process could be utilized in other industries that require limestone being converted to lime, like iron and aluminum purification, glass, paper and sugar production and agriculture.
written by Mr. Thomas , April 25, 2012
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