Thermodynamic study of a novel lignite poly-generation system driven by solar energy

A novel integrated solar-hybrid lignite upgrade and utilization system incorporating solar energy collection, lignite drying, pyrolysis, gasification, and a power generation unit is proposed in this study to promote solar energy utilization and improve energy efficiency for lignite-based power generation. Detailed analytical models based on energy, exergy, and material balance are developed and the overall system thermodynamic performance is assessed. Moreover, a comparative study between the proposed and previous systems is performed. Results of the proposed system on a typical sunny day show that net energy efficiency can reach 56.60%, which exhibits an improvement of 8.30% from the reference system; net exergy efficiency reaches 55.25%; and average and maximum energy efficiencies of the entire integrated system are 34.29% and 38.85%, respectively. Solar energy proportion can reach 74.33%, and lignite upgrading factor significantly increases to 1.79, which is a clear improvement from findings of previous studies. This result suggests that solar energy is beneficially converted into chemical energy and stored in products. The proposed concept may provide a new efficient approach to advancing solar-lignite hybridization power generation.