Optimization of supercritical CO2 cycles for biomass cogeneration for industrial applications

The industrial sector emitted 9.0 gigatonnes of CO₂ in 2022, representing 25 % of global emissions, highlighting the urgent need for decarbonisation strategies. Biomass-fuelled Combined Heat and Power (CHP) systems offer a promising pathway to reduce primary energy demand and industrial emissions. This study evaluates three supercritical CO₂ (sCO₂)-based cogeneration architectures compared to standard biomass-fuelled Rankine cycles to assess their potential for enhanced energy and economic performance. The systems were designed to serve an industrial load of 10 ton/hour of 16-bar steam and 8 MW of electricity, typical of a tissue paper mill. Key parameters, including electrical efficiency, primary energy savings (PES), capital expenditures (CAPEX), and levelized cost of electricity (LCOE), were optimized and analyzed. Results demonstrate that at a turbine inlet pressure of 300 bar, sCO₂ cycles achieve a PES of up to 13.8 %, significantly outperforming the Rankine cycle (1.9 %). CAPEX for sCO₂ systems ranges from €32 million to €40 million, comparable to or lower than Rankine cycles of similar size. Biomass consumption is reduced by 3,500–4,000 tons annually, as reflected in LCOE values of €0.086–€0.095 per kWh_el. These findings suggest that sCO₂ cycles are a viable and efficient alternative for biomass-based CHP systems, particularly in biomass-scarce scenarios.