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In the near future, shale gas will likely emerge as another coal competitor in the UK, which has aggressively begun attempts to replicate the North American success. In contrast, other countries, such as France, the Netherlands and Germany, view shale gas extraction techniques with reservation and concern due to the possible environmental and geological impacts, notably contamination of aquifers and disturbance of the tectonic plates in the earth’s lithosphere posing earthquake risks. The European Commission is hoping to finalise a fracking risk-management strategy this year. It will, however, be some 3 – 5 years before debutant countries are able to tap into their large deposits of natural gas trapped in shale pockets several hundred metres below the earth’s surface.
Worldwide, there has been a fall in the ratio of coal reserves to production (RP), which has prompted questions over whether coal use has reached a point beyond which the potential for its economical extraction will decline. Natural gas and oil are not immune to future uncertainty and any suggested scarcity will drive deep-ground coal extraction. However, recent falls in the RP ratio can be attributed to the lack of incentives to determine and prove reserves, rather than a lack of coal resources. Coal reserves will be extended through ongoing and improved exploration activities and advances in mining techniques that allow access to previously inaccessible reserves.
Renewable energy programmes delivering carbon neutral and low cost energy solutions to the planet have not materialised. The increasingly visible wind farms and solar panels most often owe their existence to government subsidies. Projects such as these can achieve a proportion of the renewable energy targets for CO2 emission reductions; however, in the absence of subsidies, they are commercially expensive, as demonstrated by a cement plant in California,4 which installed wind turbines to generate electricity.
A calciner operating under CCS conditions is predicted to lose energy efficiency without having to go through major redesign/alterations (i.e. 6% lower calcination and 2% higher temperatures). The predicted CO2, calcination and temperature contour are from the MI-CFD model.
The primary clean coal initiative in the cement industry is based on carbon capture and storage (CCS) and involves the enrichment of CO2 via oxygen injection. This requires a redesign of almost all of the major components of a plant, the most critical element being the calciner, where the appropriate retention time for effective calcination still needs to be demonstrated. CO2 enrichment inhibits the release of CO2 from CaCO3 (calcination) – Figure 2. The European Cement Research Academy (ECRA) has been studying this issue as part of its CCS programme for the cement industry over the past five years. The results have so far been encouraging and the programme is seeking funds for a CCS demonstration cement plant. HeidelbergCement, with the assistance of Norwegian R&D institutes and Norwegian industry, has initiated feasibility studies to look at the possibility for CO2 capture at its Norcem Brevik plant. The project will examine to what extent excess energy from the production of cement can be used to capture CO2. The study will also establish important knowledge about related challenges facing the cement industry and evaluate how different technologies can be combined to capture CO2 from cement plants.
The Global CCS Institute has released its 2012 report on the status of CCS, in which it says that in order for global temperatures to rise no more than the targeted 2 °C, 130 CCS plants worldwide would be needed to be online by 2020. However, it states that only 16 are currently in operation, with only a further 51 scheduled to be completed by 2020, some of which are unlikely to go ahead due to economic and political issues. The cement industry, due to its significant CO2 emissions from the calcination reaction, as well as from combustion, will undoubtedly soon be asked for a contribution.5
Having experienced a difficult time of reduced or stagnant production, the cement sector will hopefully see long-term growth through cheaper fuels and electricity tariffs and a strengthening world economy. As cement consumption increases, coal is likely to be the preferred fuel, at least in the sold-out markets, as the use of petcoke and/or secondary fuels will not be an economical option.
References and notes
- GUENIOUI, K., ‘Natural gas shortage in Egypt hits cement production’, www.worldcement.com
- BUTENKO, A., “The future of coal in Russia”, OJSC SUEK Strategy and Corporate Development Department, March 2011.
- Calport’s wind farm in Califonia, US.
- “CCS – Carbon Capture and Storage”, European Cement Research Academy (ECRA), www.ecra-online.org/226/
Read the article online at: https://www.worldcement.com/special-reports/11062014/an_intricate_relationship_part_2_326/