Evaluation of Organic Rankine Cycle alternatives for the cement industry using Analytic Hierarchy Process (AHP) methodology and energy-economic-environmental (3E) analysis

In the cement industry, energy efficiency and CO₂ reduction are crucial Waste Heat Recovery (WHR) systems play a vital role. This study examines WHR systems' optimisation, evaluating three power cycle variants: simple ORC, RORC and TLC. Decision-making was guided by the Analytical Hierarchical Process (AHP), a multicriteria methodology that provides a systematic framework for evaluating multiple alternatives under different criteria. This study considered four criteria and five scenarios: net present value, investment cost, CO₂ emissions avoided and net-work produced. The AHP methodology allowed a flexible weighting of these criteria based on their importance. Overall, the RORC outperformed the other alternatives regarding power generation, emission reductions, and net present value. However, the results depended on the operating conditions and the selected working fluid. The optimal choice varies depending on the priorities of the plant. For example, if minimising investment cost is prioritised, simple ORC might be preferred. This study highlights the multicriteria evaluation importance and the use of decision-making tools such as the AHP to select the best alternative based on the specific needs of each plant. In this way, it provides valuable guidance for the implementation of WHR systems, underscoring the importance of considering the specific circumstances of the plant.