Decarbonizing cement production

Paul Fennell is a professor of clean energy at the Department Chemical Engineering, Imperial College London. His work encompasses decarbonization and re-thinking industrial processes, including production iron steel cement manufacture. He also works in broader field decarbonization, synergies between industry power generation.Steve Davis Earth system science civil environmental engineering University California, Irvine, where he researches trends drivers GHG emissions, net-zero emissions systems, impacts production, climate change, international trade.Aseel Mohamed received an MSc advanced chemical from Her research focused on investigating various technologies used to capture CO2 order mitigate change effects. generation. Steve trade. Aseel The global ordinary Portland (OPC) approximately 3.5 billion tons annually. It crucial material for building, make concrete, mortar, other products. However, increasing attention being paid cement-related which are significant—constituting around 7%1International Energy AgencyTechnology Roadmap—Low-Carbon Transition Cement Industry.2018Crossref Google Scholar total annual emissions. Environmental reports major Western companies (Cemex, Heidelberg Cement, LafargeHolcim) reveal that 561–622 kg emitted per ton produced, with differences related materials produce cement, type kiln used, fuels burned, though there can be significant variation globally. OPC composed number materials, most important largest proportion (around 95 wt %) “clinker” supplementary cementitious (SCMs) (discussed below). remaining 5 % gypsum (added aid controlling setting time). Figure 1A shows current process includes three main stages: raw extraction preparation, clinker grinding. Limestone (CaCO3) feed constituent. Our baseline modern plant, fired exclusively fossil fuels. After limestone ground together minor constituents, calcined 900°C through series cyclones. majority needed products calcination process; pre-calciner uses 60% produces unavoidable “process” plant.2Schorcht F. Kourti I. Scalet B.M. Roudier S. Delgado Sancho L. Best Available Techniques (BAT) Reference Document Production Lime Magnesium Oxide. Joint Research Centre European Commission, 2013https://doi.org/10.2788/12850Crossref Scholar,3Davis S.J. Lewis N.S. Shaner M. Aggarwal Arent D. Azevedo I.L. Benson S.M. Bradley T. Brouwer J. Chiang Y.-M. et al.Net-zero systems.Science. 2018; 360: eaas9793https://doi.org/10.1126/science.aas9793Crossref PubMed Scopus (583) Once mixture leaves, it enters rotary kiln, reactions occur 1,450°C–1,500°C, (a calcium silicates) produced. Concrete produced when aggregates added cement. during involve (rapid, over course hours days) hydration trisilicate (Ca3SiO5) alite (slower, days weeks) Ca2SiO4, belite, cause bulk hardening via precipitation silicate hydrates hydroxide. Both continue until completion. aim this commentary give brief very simple overview options their interplay terms direct process, bounding relative importance value. Here, we discuss potential different measures, as well combinations, shown 1B. capital costs will not explored; rather, focus only potential, challenges, ultimate limits technologies. A plant requires ?3.3 GJ thermal clinker,2Schorcht twice thermodynamic minimum (the calcine drive clinkering reactions). Efficiency improvement has been incremental recent years, expected mature industry; average intensity across globe fell 3.75 GJ/t 2000 3.5GJ/t 2014, ?0.5% year.4WBCSD Sustainability InstituteGlobal Database Information.http://www.wbcsdcement.org/index.php/key-issues/climate-protection/gnr-databaseDate: 2015Google Given both fuel-related account modification efficiency mitigation. improved recovery, waste heat dry semi-dry processes2Schorcht (essentially, historically plants would by producing slurry using water, but evaporation water intensive). Carbon storage (CCS) numerous pilot larger-scale demonstrations planned. possible use alternative (refuse-derived wastes, biomass, or hydrogen) potentially electrically parts process. must considered some cases these alternatives could reduce increase indirect particular hydrogen electrification. Finally, might reduced reducing demand clinker, such substituting materials. 1B outlines approaches mitigating discussed further below. There losses (about 35%–40%) manufacturing mainly result air stream cool 100°C flue gases. fraction input lost convection pre-heaters discharge, dust, radiation. We have electricity our analysis; assumed sum WHR offset demand, require traditional steam organic Rankine cycle. steam-based Rankine-cycle-based systems convert electricity, large plant.5Pradeep Varma G.V. Srinivas Design analysis cogeneration recovery factory.Case Studies Thermal Engineering. 2015; 5: 24-31https://doi.org/10.1016/j.csite.2014.12.002Crossref (29) below considers fuel use. SCMs properties therefore replace clinker.6Taylor, H.F.W. (1990). Chemistry (Academic Press Ltd.).Google Many tested SCMs, copper tailings sugar cane bagasse more commercially (but possibly availability world moves net zero) pulverized coal fly ash (PFA) granulated blast furnace slag (GGBS). Of course, associated partitioning final complex. construction managers become comfortable substitutions because greater experience globally them, amount given volume decreased. Currently, ratio (kg cement) 0.7, heavily influenced Chinese clinkers, now starting fewer SCMs.7Andrew R.M. Global production.Earth Syst. Sci. Data. 10: 195-217https://doi.org/10.5194/essd-10-195-2018Crossref (481) assume base content reasonable reduction 0.6 investigated effects down 0.5, appropriate so-called LC3 (limestone clay cements). These promising cement8Scrivener K. Martirena Bishnoi Maity Calcined Clay Cements.Cement Concr. Res. 114: 49-56https://doi.org/10.1016/j.cemconres.2017.08.017Crossref (323) similar currently commercial cements so face lower barriers commercialization than novel formulations. substantially overall compared those fossil-fueled ensuring benefits careful traceably certify reductions. According International Agency,9IEA Bioenergy (2003). Municipal Solid Waste Its Role Sustainability. https://www.ieabioenergy.com/wp-content/uploads/2013/10/40_IEAPositionPaperMSW.pdf.Google 80% carbon municipal solid biogenic nature; 0.7 here. replacement waste-derived cost-saving way use, addition relatively environmentally friendly method management, particularly if care taken divert all recyclable prior kiln. Biomass another option assuming biomass neutral. Lafarge, part Canadian 2020 project, run up 10% substitution its Bath Ontario. were hemp, sorghum, willow, switchgrass, oat hulls first phase, challenging demolition wood, treated telegraph poles, etc. (and investigation pre-processing enable hotter flame) second phase. Reports positive, permits applied 30%, little reported since 2018. suggest biofuels (outside wastes) remain several times expensive unit provided coal.10Cuellar A. Herzog H. Path Forward Low Power Biomass.Energies. 8: 1701-1715https://doi.org/10.3390/en8031701Crossref (31) In vein, and/or electrification provide 100% system, magnitude reductions complexity cost designing deploying hydrogen-driven kilns high. Importantly, no avoids CaCO3 (?60% total). control next-generation measurement devices significant. LafargeHolcim leader area started “Plants Tomorrow” initiative, roll out robotics, AI, predictive maintenance.11LafargeHolcimIndustry 4.0 production: launches Tomorrow.”.https://www.lafargeholcim.com/launch-plants-tomorrowDate: 2019Google certified under scheme stated 15%–20% operational gain. More LafargeHolcim’s already connected technical information allowing performance tracking allocation resources centrally.11LafargeHolcimIndustry challenge converting company’s gain approximate value assumed. Traditionally, calcining limestone, combined into single-flue gas passes preheating train plant. Because high concentration (14%–33% volume), basic thermodynamics indicate general easier equivalently sized natural (?3%) coal-fired (?15%) plant.12Bui Adjiman C.S. Bardow Anthony E.J. Boston Brown P.S. Fuss Galindo Hackett L.A. al.Carbon (CCS): forward.Energy Environ. 11: 1062-1176https://doi.org/10.1039/C7EE02342ACrossref presence NOx, SO2 SO3, trace species complicate picture. types CCS: post-combustion capture, oxyfuel combustion, pre-combustion (here covered “hydrogen fuel”). context, separation reactor (DSR) recently developed Australian company Calix.13Hills T.P. Sceats Rennie P. LEILAC: Cost Capture Industries.Energy Procedia. 2017; 6166-6170https://doi.org/10.1016/j.egypro.2017.03.1753Crossref (22) Post-combustion involves removing either retrofitted existing built end-of-pipe technology new plants. necessary go detail except mention multiple types, suited others. increased certain CCS. takes place after burnt pure oxygen recycled CO2) instead air. was promoted CCS nitrogen flowing theoretically lowers consumption. issues atmosphere;14Zheng Hills Phase evolution, characterisation, prepared oxy-fuel atmosphere.Faraday Discuss. 2016; 192: 113-124https://doi.org/10.1039/c6fd00032kCrossref (13) however, difficult retrofit This allows capture. Capital mean co-location producer, complex, preferable. DSR comprises limestone. large, externally heated tube calcines falls vertically. re-engineering almost-pure released without (except decrease due less efficient firing calciner) additional costs. noteworthy Norcem’s Longship project Brevik, Norway, positive investment decision Norwegian government full-scale demonstration, leading degree certainty available cement.15CCS Norway.https://ccsnorway.com/capture-norcem/Google section estimates relation (only i.e., considered) (S) Sbase (0.7, above), improvements utilizing fuel. estimations precise need proper life-cycle validated, case bioenergy production. Additionally, they do take changes changed C/H approximation calculated Equation 1, CO2process (before considering capture), CO2fuel 3, CO2biomass growth estimated 4, CO2captured captured technology, 5. CO2reabsorbed reabsorbed carbonation.CO2total=CO2process+CO2fuel?CO2biomass?CO2captured?CO2reabsorbed(Equation 1) 2, P 0.6, above:2Schorcht ScholarCO2process=SSbaseP.(Equation 2) 3 D fractional digitalization, set 0.1 considered), (1 ? P) E any (0.05 H (by content, switching hydrogen). Results equivalent electrification.CO2fuel=SSbase1?D1?E1?P1?H(Equation 3) To determine fuel, F, neutral, haveCO2biomass=SSbase1?D1?E1?PF,(Equation 4) C byCO2captured=CCO2fuel+CO2process.(Equation 5) once concrete put place, reabsorbs carbonation. decadal time span; thus, usually included. purpose completion, 1. Xi al.,16Xi Ciais Crawford-Brown Guan Pade C. Shi Syddall Lv Ji al.Substantial Uptake Carbonation.Nat. Geosci. 9: 880-888https://doi.org/10.1038/ngeo2840Crossref (212) CO2reabsorbed, R, 5% vary depending host factors. 2 application CSS variety fossil- non-fossil-based fuels, improvement, substitution, combination each “zero” case, fossil-fuel-fired instructive examine (i.e., left-hand axis 2A). Changing efficiency, highly financially profitable, small noticeable effect. clear shift to, e.g., effect near zero