Carbon dioxide accounts for more than 90% of worldwide CO2-eq greenhouse gas (GHG) emissions from industrial sectors other than power generation. Amongst these sectors, the cement industry is one of the larger industrial sources of CO2 emissions. Notably, cement manufacturing was responsible for about 6% of the global anthropogenic CO2 emissions in 2005. Further, global production of cement has been growing steadily, with the main growth being in Asia. China, in particular, now accounts for almost half of the global cement production . Considering these trends, the worldwide cement industry is a key industrial sector relative to CO2 emissions.
The development of policy options for managing emissions and air quality can be made more effective and efficient through sophisticated analyses of relevant technical and economic factors. Such analyses are greatly enhanced by the use of an appropriate modeling framework. Accordingly, the ISIS model for industrial sectors is under development at the U.S. Environmental Protection Agency (U.S. EPA). Currently, this model is populated with data on the U.S. cement-manufacturing sector and efforts are underway to build representations of the U.S. pulp and paper and iron and steel sectors. The cement industry representation in the ISIS framework is referred to as ISIS-cement.
In this chapter, ISIS-cement was used to conduct an example analysis of the U.S. cement sector to gain some insights relative to two broad questions: (1) what range of CO2 reductions options may be practicable in the near-term, and (2) for that range, what may be the market characteristics for the U.S. cement industry. These questions are relevant because in the absence of carbon capture and sequestration technology, the path forward for reducing CO2 emissions in the near-term (decade ending 2020 selected for this work) will need to depend on the available energy efficiency measures and raw material and product substitution options. Only the energy efficiency measures for clinker making and plan-wide application were considered in this example analysis because calculation procedures for other energy efficiency measures associated with raw material preparation and finish grinding still need to be included in ISIS-cement. In addition to the energy efficiency measures, a fuel substitution technology, MKF-tires, and a raw material substitution technology, CEMstar, were also included in the analysis.
The example analysis reflects that, based on CO2 allowance prices, a range of CO2 reductions, 5-15%, from the projected 2013 emissions appears to be practicable. For this range, the drop in U.S. industry revenue under policy ranges from about 4% to 6.5% of the revenue in the BAU case and the increase in cement price (in 2013 for example) ranges from about 5% to 12% relative to the BAU. Significant collateral reductions in other pollutant emissions may be possible under the range of 5-15% CO2 reductions. For example, at the 15% CO2 reduction level, each of NOX and SO2 emissions may be reduced by more than 200,000 short tons over the selected time horizon. To meet a CO2 reduction level of 15% from the projected emissions in 2013, the U.S. cement industry would potentially use multi-pollutant energy efficiency improvement options and reduce domestic production.
The results of the example analysis presented above are indicative only for several reasons. First, as mentioned before, the analysis did not include the full suite of abatement options potentially available in the near-term. In particular, it did not take in to account the energy efficiency measures of Tables 8.3 and 8.5 and feasible raw material and product substitution approaches. Second, some assumptions associated with the abatement measures considered need additional evaluation. In particular, availability of materials (e.g., blast furnace slag, tires) and the degree to which a specific abatement measure could be applied across the industry need further assessment. Finally, extra-U.S. CO2 emissions associated with imports need to be taken in to account while developing policy options. These areas need to be addressed to permit more comprehensive evaluation of the CO2 reduction potential relative to the U.S. cement industry. Work is being initiated to address these areas and modify ISIS-cement as needed.
The focus of the example analysis presented is on modest CO2 reductions potentially possible with use of energy efficiency approaches in the near-term. It is recognized, however, that in the longer-term more significant CO2 reductions (e.g., greater than 50%) perhaps can only be achieved with use of CO2-specific mitigation technologies, which are currently under development.
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