Benchmarking energy utilization in cement manufacturing processes in Nigeria and estimation of savings opportunities

Abstract

Nigeria is a leading producer of cement in Africa. Because cement production is energy intensive, with significant adverse impacts on the environment, an apparent need exists to assess the Nigerian cement industry to identify energy use mitigation options. The potentials for reducing energy use in typical Nigerian cement manufacturing plants, through the implementation of available energy efficiency measures, were assessed in this study, alongside the attendant costs of implementing those measures. To achieve these, using numerous globally available energy efficiency technologies and measures, energy conservation supply curves were constructed for three Nigerian cement manufacturing plants which operate on wet, semi-wet, and dry cement manufacturing processes, respectively. Comparisons with global best and Chinese benchmark plants with respect to thermal and electrical energy consumption were also made. The comparisons showed that, with respect to the global benchmark plants, thermal energy savings of between 19.83 and 52%, and electrical energy savings of between 35.23 and 43.10%, were possible. With respect to the Chinese benchmarks, thermal energy savings of 10.74–47.32%, and electrical energy savings of 20.95–30.17%, could be achieved. The plants considered performed significantly less than either of the benchmarks in terms of both thermal and electrical energy usage. The energy conservation supply curves for the plants showed that implementing the cost-effective energy efficiency measures could lead to energy savings of about 235,038, 237,913 and 374,055 GJ/year, for the wet, semi-wet, and dry cement manufacturing plants, respectively. Furthermore, technically feasible efficiency measures could yield energy savings of about 250,272, 259,795 and 395,447 GJ/year, respectively. Achieving these savings will improve profitability in the Nigerian cement industry and make the unused energies available for utilization in other sectors of the Nigerian economy.