Sustainable multi-generation of district cooling, electricity, and regasified LNG for cooling-dominated regions

Multi-generation concepts combining low-to-medium grade environmental or waste heat utilization, and waste cryogenic cold recovery, are investigated for (i) direct and indirect district cooling (DC) using a direct refrigeration unit and open Rankine cycle-driven compression chiller, respectively, (ii) district electricity generation using closed organic Rankine- or Brayton-based cycle configurations, and (iii) LNG regasification for local gas distribution. The Rankine-based system can yield net equivalent energy savings of approximately 41 kWh/ton_LNG at effective first-law and effective exergy efficiencies of 24 % and 26.2 %, respectively, and the Brayton-based system, 135 kWh/ton_LNG, at 43.1 % and 45.5 % efficiencies, respectively. Per MTPA_LNG regasification capacity, the Rankine- and Brayton-based systems could deliver 12.4 and 22.1 MW of DC, respectively, while generating 2.4 and 9.4 MW of net electrical power for the district, with 6.4 and 19.5 ktons of natural gas saved annually, respectively, and avoiding 16.9 and 51.5 kt of CO₂-equivalent emissions annually, respectively. At a low-bound electricity tariff, corresponding net annual economic benefits of 5.3 and 8.3 million USD could be obtained for the Rankine- and Brayton-based multi-generation systems, with corresponding payback times of 2.6 and 3.9 years, respectively. Further environmental benefits would be achieved through reduced use of conventional refrigerants, and reduced impact on marine ecosystems.