The technical perspective
The calorific values and compositions of shale gas are only slightly at variance with natural gas, so shale gas is equally appropriate for many industrial applications where conventional fuels are utilised. However, due to an occasional higher proportion of impurities1 in shale gas, it is usually blended with natural gas. Many cement plants globally have no experience with the use of natural gas, largely because it is not available onsite due to its traditionally higher price. Based on the fact that the stoichiometric air requirements of natural gas are some 4 – 5% greater than coal, it is generally assumed that a cement plant would lose about 4 – 5% production by switching from coal/petcoke to natural gas. This is a false perception. Due to the ease with which natural gas mixes with the air and burns, the volumetric flow of the gases exiting the tower can be reduced by nearly 8% by reducing the excess air. Therefore, an increase in clinker production of 5 – 10% is achievable firing natural gas. In addition to the potential for higher clinker production and the falling price of natural gas energy, further benefits of firing natural gas are the savings on coal grinding and handling costs. A detailed technical perspective of switching from coal to natural gas is presented elsewhere.2,3
The energy balance outlook
Renewable energy programmes delivering carbon neutral and low cost energy solutions have not materialised. The increasingly visible wind farms and solar roofs most often owe their existence to government subsidies. Projects such as these can achieve a proportion of the renewable energy targets for CO2 emissions reductions, but in the absence of subsidies they are commercially expensive and will not be adopted.
European industries are currently paying nearly four times as much for natural gas as their US counterparts. The opportunity for European manufacturing to compete with the US simply does not exist. As a result, some European manufacturing is moving to the US ‘energy haven’. This displacement is not too difficult for the large multinationals, as exemplified by BMW’s recent relocation of its carbon fibre production to the state of Washington at a cost of US$100 million. The US-produced vehicle panels are shipped back to its European assembly plants.4
Last year, with the help of the German government, an E.ON gas-fired power plant was saved from closure, having been priced out by cheap coal and nuclear power. The assistance was welcomed by the industry and provides a precedent for gas-fired power plants, which are otherwise unprofitable due to high gas prices. As reported in the Financial Times, government incentives have promoted renewable fuels for electricity production in Europe. Otherwise European power plants are making use of cheap coal imported from the US. In the US, coal prices are being driven down by lower natural gas prices due to the shale gas ‘revolution’. Drax, the UK’s largest power generator (4000 MW), is a world leader in the conversion from coal to biomass to avail ‘green’ energy credits. Its first converted boiler unit is due to be operational this year, and its third by 2016, giving a total generation capacity of 2000 MW using 100% wood pellets sourced from forestry waste.
Increasing water scarcity due to population growth, increased industrial activity and climate change causing unpredictable rainfall patterns mean that water issues will become increasingly debated in the energy future. Both energy crops and fracking techniques used in shale gas extraction depend highly on the excessive use of water; the former will compete with food production and the latter with conventional fuel, where little or no water is required.
Switching from coal to natural gas will almost halve global CO2 emissions, but the carbon balance still has to be taken into account in future planning. The Global CCS5 Institute has released its 2012 report on the status of carbon capture and storage, in which it says that to be on track to limit the global temperature rise to 2 °C, a total of 130 CCS plants worldwide would need to be online by 2020. However, it states that only 16 are currently in operation, with a further 51 scheduled to be completed by 2020, though some of these are unlikely to go ahead due to economic and political issues. Undoubtedly, due to its significant CO2 emissions, the cement industry will soon be asked to contribute. To address this, a comprehensive CCS assessment project has been undertaken by ECRA (the European Cement Research Academy) where an integrated approach from raw feed to clinker production analyses the effects of CO2 enrichment through oxygen injection on all components of a pilot cement plant.6
The cement industry, having been through a difficult time of reduced or stagnant production, will hopefully see long-term growth through cheaper fuels and electricity tariffs and a strengthening world economy. To a significant extent, this revival will be due to the discovery of additional natural gas resources, shale gas and ice gas, which are taking the world energy market by storm.
- I.e., Hydrogen sulfide, sulfur.
- EPA report no LBNL-54036, citing Caddett, 1997, Caddet, 1998.
- Akhtar, S.S., Ervin, E., Raza, S. and Abbas, T., (2013): ‘From Coal to Natural Gas: Its Impact on Kiln Production, Clinker Quality and Emissions’, 55th Cement Industry Technical Conference, IEEE-IAS/PCA, 14 – 18 April 2013, Orlando.
- Carbon capture and storage.
Written by T. Abbas. This is the second part of a three-part article, originally published with additional Figures in the November 2013 issue of World Cement. To see the article in its entirety, subscribers can sign in here.
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Read the article online at: https://www.worldcement.com/the-americas/02012014/natural_gas_from_scarcity_to_abundance_part_three_8/