Analysis of energy efficiency improvement potential in the cement sector

This study investigates the energy efficiency improvement and CO2 abatement potential in the Swiss cement industry by means of energy efficiency cost curves. While these curves have been used to determine the potentials in some other countries, there are no comparable analyses available in the literature for Swiss cement plants at the level of detail analyzed in this study. The energy savings potential for this sector is estimated based on the data collected from literature and via interviews with the experts.The collected information reveals the current economic potential for final energy savings to be 14% (see Figure 1) while the economic CO2 abatement potential without carbon capture and storage (CCS) is estimated at 13% (see Figure 2). Accounting for payback periods as applied in industry, the economic final energy savings potential decreases from 14% to around 8%. It should be noted that the results presented in this study are subject to various types of uncertainties with the most notable being the current diffusion levels, final energy prices and CO2 prices during the course of the measures’ lifetime, project costs, energy mix of the Swiss cement sector in future and how the economic potential is going to be realized over time. Accounting for most of the uncertainties mentioned above, high and low emission scenarios have been generated according to which the economic final energy savings potential decreases by up to 7% and increases by up to 15% respectively.

Figure 1 Final energy efficiency cost curve for Swiss cement industry in 2016, case of total investment

 

Low final energy prices is a major economic barrier to energy efficiency improvement. The electricity price currently paid by the Swiss cement sector is very low (nearly 36.21 CHF/GJ, lowest price category I7 for large consumers by Swiss Electricity Commission (ElCom). Sensitivity analysis as performed in this study shows that even 50% increase in the electricity price is unlikely to bring any significant change in the economic potential while a lower electricity price would make high-pressure roller press economically unviable, which is expected to bring the maximum electricity savings. The relatively low fuel costs due to use of large amounts of coal and waste is possibly one reason why one cement plant still operates a lepol kiln. The largest share of CO2 abatement can be achieved by CCS. However, the cap-and-trade CO2 price paid by the Swiss cement plants is 87% less than the CO2 tax which is a limiting factor for implementation of not only CCS but also other clean energy technologies in the cement plants. On the other hand, a very high CO2 tax in Switzerland would make it difficult to sustain international competitiveness. From a policy perspective, these barriers could be overcome by more rigorous yet sustainable tax reforms and/or subsidies of energy efficiency measures to accelerate penetration of green technologies into the sector.

Figure 2 CO2 abatement cost curve for Swiss cement industry in 2016, case of total investment

 

Apart from the final energy prices, there are also non-monetary barriers, for example, space issues associated with the installation of more efficient classifiers, permit issues limiting installation of an additional preheater stage, unavailability of the suitable waste fuels for kiln firing etc. Some measures (e.g. cyclones with lower pressure drop) can only be implemented in case of capacity expansion. Regardless of whether the CO2 tax is in place or not, operating costs of the CCS can be reduced significantly by utilizing low quality waste heat for generating low pressure steam (nominal 3.4 bar;  Hassan, 2005; WBCSD/ECRA, 2009) which is the largest single operating cost item for CCS (Hassan et al., 2007); however, the measure competes with ORC installations and/or district heating which raises the question of a suitable choice. In addition, CCS increases final energy use of a facility while decreasing significant amount of CO2 emissions at the same time. Hence, a dedicated analysis is required to compare the potential benefits by other measures competing with CCS. Innovative technologies (e.g. Celitement) have also been analyzed for their potential applicability; further research should analyze these options in more detail including the associated techno-economic data as the technologies are either too expensive or have not yet reached the market maturity.

 

References

Hassan, S.M.N., 2005. Techno-Economic Study of CO2 Capture Process for Cement Plants.

Hassan, S.M.N., Douglas, P.L., Croiset, E., 2007. Techno-Economic Study of CO2 Capture from an Existing Cement Plant Using MEA Scrubbing. International Journal of Green Energy 4, 197–220.

WBCSD/ECRA, 2009. Development of State of the Art-Techniques in Cement Manufacturing: Trying to Look Ahead   (CSI/ECRA-Technology Papers).