Cumulative solar exergy allocation in heat and electricity cogeneration systems

• Published in: Energy (Oxford) Vol. 254; p. 124464
• Main Authors: Ren, Siyue, Feng, Xiao, Yang, Minbo
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2022
• Subjects: Allocation method; Cumulative solar exergy; Emergy transformity; Heat and electricity cogeneration; Heat and electricity cogeneration; Emergy transformity; Cumulative solar exergy; Allocation method
• ISSN: 0360-5442
• DOI: 10.1016/j.energy.2022.124464

Heat and electricity cogeneration is effective to improve energy efficiency but with no a unified allocation method. Both the emergy and cumulative exergy methods could evaluate the resources consumption, with the issues caused by total inheritance principle and inequivalence of primary exergy, respectively. This paper takes solar exergy as the basis for cumulative exergy, proposing a concept of cumulative solar exergy (CSE), which provides a new insight for allocation problems and sustainability evaluation. The CSE allocation is performed by taking the CSE transformities (TrCSE) in the stand-alone heat and electricity generation systems (alternative systems) as baselines. The CSE method is applied in the biomass and coal gasification cogeneration systems, with back pressure steam turbine (BPT), extraction condensing steam turbine (ECT) and gas-steam combined cycle (GSC) taken as power generation facilities. The results show that the TrCSE of biomass-based systems are lower than those of the coal-based systems. The resource utilization efficiencies can be improved by cogeneration according to the TrCSE of cogeneration and alternative systems. The allocation results of CSE and exergy methods are in the range of energy and enthalpy drop methods. The electricity coefficients of the CSE method are higher than those of the exergy method. •Emergy concept and cumulative exergy method are combined.•Cumulative solar exergy allocation method is proposed.•Biomass and coal gasification cogeneration systems are studied.•Allocation of the systems with different power generation facilities is performed.•Results are compared with those of energy, exergy and enthalpy drop methods.