Last month, the World Business Council for Sustainable Development (WBCSD) and the International Energy Agency (IEA) published a road map that calls for strong national policies as well as actions to develop commercially viable carbon capture and storage technologies to reduce global CO2 emissions from the cement industry.
The cement roadmap outlines a possible transition path for the industry to make continued contributions towards a halving of global CO2 emissions by 2050. It estimates that the cement industry could reduce its direct emissions 18% from current levels by 2050.
The report also mentioned a number of low-carbon or carbon-negative cements currently being developed by start-up companies such as Novacem, Calera, and Calix who are expecting to build pilot plants in 2010/11. The report also mentioned geopolymer cement as another technology that have already been commercialized in small-scale facilities, but have not yet been used in large-scale applications.
Geopolymer cement utilises waste materials from the power industry (fly ash, bottom ash), the steel industry (slag), and from concrete waste, to make alkali-activated cements. This process was reportedly developed in the 1950s.
Novacem’s cement, meanwhile, is based on magnesium silicates rather than limestone (calcium carbonate) as is used in Ordinary Portland Cement. Novacem estimates that for every tonne of ordinary Portland cement replaced by Novacem cement, around 0.75 tonne of CO2 could be captured and stored indefinitely in construction products.
Calera’s cement is a mixture of calcium and magnesium carbonates, and calcium and magnesium hydroxides produced by bringing sea-water, brackish water or brine into contact with the waste heat in power station flue gas, where CO2 is absorbed, precipitating the carbonate minerals. Last December, Calera and Bechtel Power Corporation formed an alliance to develop and construct facilities using Calera’s carbon capture technology.
Australia-based Calix owns a minerals processing technology called Flash Calcination, where its cement is produced in a reactor by rapid calcination of dolomitic rock in superheated steam. The CO2 emissions can be captured using a separate CO2 scrubbing system.
Another cement company from Mexico, Cemex, announced last month its strategies to tackle climate change. Cemex made a commitment to reduce CO2 emissions per metric ton of product 25% from the 1990 levels by 2015.
In cement production, the company said it is using a smaller percentage of the energy intensive ingredient clinker in their end product by substituting clinker with alternative materials such as by-products from other industries, primarily fly ash from coal-fired power stations and blast furnace slag from the steel industry.
Cemex is also involved in carbon capture projects and has even received a $1.1m grant from the US Department of Energy (DOE) last October to develop technology for capturing and storing carbon dioxide emissions at one of CEMEX’s US cement plants.