Techno-economic analysis of waste heat recovery power plants in cement industry – A case study in Ethiopia

Cement manufacturing is a highly energy-intensive process, with a significant amount of the thermal energy in the production chain being lost. Consequently, exploring ways to capture and utilize this wasted heat to generate electricity and meet industrial energy requirements is crucial. This study investigates the potential for Waste Heat Recovery (WHR) power generation with a case study in the Ethiopian cement industry. The levelized cost of energy (LCOE) and the Net Present Values (NPV) of the WHR power plant based on 3 options (i.e., steam Rankine cycle, Organic Rankine cycle, and Kalina Rankine cycle) are evaluated. The findings reveal that the steam Rankine cycle-based waste heat recovery power plant is the only feasible option in the Ethiopian cement plant, with a NPV of 0.35 million USD and a LCOE of about 0.04 USD per kWh. The power capacity of the feasible plant is about 8.9 MW for the studied cement plant with an annual production capacity of 2.3 Mt of cement, covering about 18% of its electricity demand. The plant's associated reduced CO₂ emissions potential is insignificant, as the hydropower sources dominate the national power grid. However, assuming the proposed WHR power plant reduces the activation of diesel power plants during peak hours in the Ethiopian power grid, the Steam Rankine Cycle (SRC)-based waste heat recovery power plant (WHRPP) in the case study cement plant has the potential to reduce CO₂ emissions by approximately 7.9 million tonnes per year. Sensitivity analysis has been conducted to ensure that the results derived from the base case assumptions remain reliable despite potential fluctuations in the key parameters. This study could be a useful reference for policymakers and industries to harness alternative and sustainable electricity generation potential from onsite power generation plants in the cement industry.