Energetic/economic/scalability assessment of active solar energy and waste heat utilization in urban environments for H2/freshwater production: A CSP-centered multigeneration system with dual-loop power generation

Abstract

The imperative to reduce greenhouse gas emissions has intensified the need for sustainable thermal energy systems. This study addresses this exigency by harnessing solar energy and exploiting waste heat to augment energy efficiency in urban settings. The proposed system integrates a concentrated solar power-based Brayton cycle with dual power generation, water desalination, and hydrogen production capabilities. Comprehensive technical and economic evaluations affirm the feasibility of this system. Additionally, transient codes have been utilized to ascertain the performance of the proposed configuration. The investigation reveals that the tower and receiver are the primary sites of exergy destruction, accounting for 48.1 % of the total, with the heliostat field, reverse osmosis, and proton exchange membrane electrolysis contributing 24 %, 8.8 %, and 6.9 %, respectively. The findings show that increasing the pressure ratio in the Brayton cycle leads to improved exergy efficiency and increased power output, but also leads to higher overall costs. A thorough economic evaluation shows that the solar unit, which includes the receiver, heliostat field, compressor, and gas turbine, is the main factor influencing costs, representing 62.6 % of the total system cost rate. The dynamic study conducted to forecast the annual system capacity in San Francisco indicates that electricity production peaks during summer at 242.15 MWh. Conversely, winter exhibits the lowest contribution at 17.3 % with 143.11 MWh.