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Solar-powered cement production without carbon dioxide emissions by ferujkll sdff
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Solar-powered cement production without carbon dioxide emissions |
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Business,Business News,Business Opportunities
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Solar-powered cement production without carbon dioxide emissions ( Nanowerk Spotlight ) The global cement industry is currently one of the largest singleemitter of carbon dioxide, generating on average about 830 kg ofthis greenhouse gas for each 1000 kg of cement produced (source:International Energy Agency 2007, Tracking Industrial Energy Efficiency and CO 2 Emissions ; pdf). Considering that the worldwide annual production of cementis a whopping 3.8 trillion kg ( source ), the cement industry alone accounts for approximately 5-6% ofman-made CO 2 emissions. In a previous Nanowerk Spotlight ( "New solar-powered process removes CO 2 from the air and stores it as solid carbon" ) we introduced a novel solar conversion process, combiningelectronic and chemical pathways, for carbon dioxide capture. ThisSTEP ( S olar T hermal E lectrochemical P roduction) process proactively converts anthropogenic carbondioxide generated in burning fossil fuels, as well as eliminatescarbon dioxide emissions associated with the generation of metalsand bleach. In a subsequent Spotlight ( "Reinventing iron production using clean renewable energyinstead of coal" ) we showed how the STEP process could be used as an effective newcarbon-dioxide-free process for iron production.
The research team, led by Stuart Licht , a professor of chemistry at George Washington University, has nowpresented a solar-powered process to produce cement without anycarbon dioxide. In a paper (accepted manuscript) in the April 5,2012 online edition of Chemical Communications ( "STEP Cement: Solar Thermal Electrochemical Production of CaOwithout CO 2 emission" ), they show that STEP-produced cement operates at solar energyconversion efficiencies higher than that in any solar photovoltaic. Conventional thermal decomposition production of lime (left) versusSTEP direct solar conversion of calcium carbonate to calcium oxide(right) eliminating CO 2 . (Image: Dr. Licht, University of Washington) "In cement production, the majority of CO 2 emissions occurs during the decarbonation of limestone (CaCO 3 ) to lime (CaO) and the remainder (30 to 40%) from burning fossilfuels, such as coal, to heat the kiln reactors to∼900°C," Licht explains to Nanowerk.
" Our studypresents a low-energy, entirely new synthetic route to form CaOwithout any carbon dioxide emission, and is based on unexpectedsolubility behavior in molten salts. This synthesis can beaccomplished without solar energy, and without our new STEPprocess, but is particularly attractive when combined with this newsolar process." "Alternatively" he adds, "the new synthesis could beused by industry to produce cement using any non-solar, renewableor nuclear energy without any CO 2 release, or greatly decrease CO 2 if fossil fuels were used to drive the new cement production– in the latter, worst case scenario, the products are lime,graphite and oxygen; there is still no CO 2 product, but CO 2 would be used in the energy to drive the process." In STEP cement limestone undergoes low energy electrolysis toproduce lime, O 2 and reduced carbonate without carbon dioxide emission. "There have been proposals to form cement which recaptures orsequesters some of the CO 2 emitted during its production process" says Licht."This, however, is the first process which forms no CO 2 while producing cement." In this new technique, the kiln limestone-to-lime process isreplaced by an electrolysis process which changes the product ofthe reaction of the limestone as it is converted to lime. Ratherthan producing carbon dioxide, it reduces the carbon dioxide (addselectrons) and produces only oxygen and graphite (which can bereadily stored as solid carbon) or CO for fuels, plastics orpharmaceuticals.
This is accomplished at low energy and highthroughput. The researchers plan to scale up the outdoor STEP cement prototypeand in general want to increase the portfolio of useful chemicalsmade by their new solar process. "The goals are to replace today's fossil fuel economy with arenewable chemical economy," says Licht. "It works finein the lab but scale-up is the challenge." He points out that, although the process is entirely new, theindividual components –solar towers, 24/7 operation storingsolar energy with molten salts – are already in place.
The bottom line of these research results is that solar energy canbe used to efficiently make products without carbon dioxide, and atsolar energy efficiencies higher than in photovoltaics. By Michael Berger. Copyright Nanowerk. I am Monitors writer, reports some information about solar exterior lights , antique china repair.
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