Cleaner production of net-negative emissions via integrated Biogas–LNG multigeneration system: 5E analysis, LCA, and artificial intelligence-driven optimization

The study introduces a novel multigeneration system powered by sorghum-fermented biogas and enhanced with LNG cold recovery, a gas turbine, an organic Rankine cycle (ORC), and a thermally integrated carbon capture unit. The system is designed to simultaneously generate electricity, heating, cooling, and captured CO₂ while achieving net-negative emissions. Integrated multigeneration systems are crucial for meeting global energy demands and environmental concerns, but conventional configurations frequently suffer from limited fuel flexibility, high CO₂ emissions, and inefficient energy integration. In order to assess system performance, a thorough 5E (energy, exergy, economic, environmental, and emergy) analyses and a life cycle assessment (LCA) were conducted. Parametric studies revealed the effects of turbine inlet temperature, ORC pressure, LNG pressure, and LNG rate. A Multi-Layer Perceptron (MLP) neural network precisely predicted important metrics (R² = 0.999), and multi-objective optimization (SPEA-II) was used to balance cost, efficiency, and sustainability. In order to achieve −386 kg/h net CO₂ emissions, the system produced 5240 kW of net power, 52.19 % energy efficiency, 40.59 % exergy efficiency, and 65.81 % CO₂ removal. Economic analysis showed a net present value of 14.19 M$, levelized cost of energy (LCOE) of 0.29 $/kWh, and payback period of 5.91 years. A total product unit cost of 23.11 $/GJ, exergy efficiency of 43.8 %, and LCOE as low as 0.228 $/kWh were obtained from optimization scenarios. For carbon reduction and sustainable energy production, this system provides a scalable solution.