Optimization of energy transition pathways in the lime industry: A superstructure approach

Lime manufacturing is a hard-to-abate industry, owing to high-temperature heat requirements and process-related CO2 emissions from limestone calcination. Although numerous mitigation technologies have been proposed, existing studies generally evaluate individual options or rely on predefined economic scenarios, providing limited guidance for technology selection under uncertain future energy and carbon prices. This study presents a systematic techno-economic assessment of multiple decarbonization options, including fuel switching, electrification, and CO2 capture (CC) with storage or utilization. A unified superstructure model is coupled with scenario analysis and a parameter sweep of key energy and CO2 prices to assess robustness under market volatility. Results show that the fuel switching alone achieves only 18% CO2 emission reduction, making CC implementation inevitable for deep decarbonization. Implementing CC enables up to 78% emission reduction for fossil-based routes and net-negative emissions down to −0.22 tCO2/tlime for biomass-based configurations, at the expense of an energy penalty of 1.4–6.2 GJ/tlime. Current economic conditions favor unabated and bioenergy-based production (€147–176/tlime vs. €257–380/tlime with CC), whereas CC becomes competitive only under high CO2 pricing, achieving cost reductions up to 45% compared to the base case. Electrification and hydrogen-based production require very low-cost (≤€62/MWh) low-carbon energy to become competitive, whereas CCU remains constrained by its high energy demand (12.2 GJ/tlime). Finally, oxycombustion appears as the most promising decarbonization pathway, as it consistently provides the best trade-off between energy penalty, CO2 emissions, total cost, and robustness to market fluctuations, outperforming amine-based capture across all pricing scenarios.