The cement manufacturing process has a staggering carbon footprint – said to be responsible for up to 7 percent of global greenhouse gas emissions, the industry releases around 9 lbs of carbon dioxide for every 10 lbs of cement produced. With global production standing at around three billion tonnes each year, there remains a huge need to find a greener method of production. While there have been various efforts in recent years, researchers at George Washington University have devised the first technique, called Solar Thermal Electrochemical Production (STEP), to completely eliminate CO2 emissions from the process, and it would even be cheaper than current methods of production.
According to Physorg, the Solar Thermal Electrochemical Production (STEP) of cement would harness the energy for two specific areas of production. When limestone is converted into lime, it undergoes a chemical change – at present, decarbonation. The limestone is separated into lime and CO2, with the greenhouse gases as the an unfortunate byproduct. Carbon emissions are further increased by the burning of fossil fuels to heat up the limestone to start the decarbonation process.
The STEP method eliminates the needs for fossil fuels — the solar thermal heat melts the limestone, which then undergoes an electrolysis process. The electrolysis produces a different chemical output, lime-intact but free of greenhouse gas byproducts. Stuart Licht, a chemistry professor at George Washington University, told Physorg, “Rather than producing carbon dioxide, [STEP] reduces the carbon dioxide (adds electrons) and produces only oxygen and graphite (which can be readily stored as solid carbon) or CO for fuels, plastics or pharmaceuticals.”
At higher temperatures STEP creates a carbon monoxide byproduct which researchers believe could be sold to other industrial applications. If this were to be done, the cost of STEP-created cement would stand at around -$298 per ton, as opposed to the current cost of standard, environmentally destructive production of $70 per ton.
With some cement manufacturers already looking into ways to reduce their industry’s footprint, STEP could transform an industry responsible for a huge quantity of greenhouse gas emissions each year — if the process can be adapted to large scale commercial use. Furthermore, simple design solutions such as Legioblocks, simple, stackable reusable Lego-like blocks of cement, as used in a recent fantastic church-inspired pavilion, could further bring the cement industry into the greener side of construction.
According to Physorg the scientists are also looking at how the STEP methods could be applied to a diverse range of industrial applications “such as purifying iron and aluminum; producing glass, paper, sugar, and agriculture; cleaning smoke stacks; softening water; and removing phosphates from sewage.”