Rational Exergy Management Model based metrics for minimum carbon dioxide emissions and decarbonization in Glasgow

Abstract

Addressing climate change is an urgent issue that requires effective and sustainable solutions at multiple scales from the building to the district and city scales. This study focuses on the avoidable carbon dioxide emissions responsibilities due to exergy mismatches between supply and demand at multiple scales based on the Rational Exergy Management Model. Nine key metrics for decarbonization are presented with analyses of three case studies in Glasgow, including a university campus area, and urban emissions scenarios. The existing campus district system involves 42 MW boiler capacity for heat supply and 3.35 MW electric power and heat supply with a combined heat and power system that is responsible for 80.97 kg carbon dioxide per operating hour at design conditions. The system may shift towards carbon neutrality if the combined heat and power system capacity increases to at least 27.3 MW electric power and the boiler is eventually banned. A potential expansion of the district network with solar prosumer buildings indicates that the optimum number of Exergy Stars as a new rating is four out of five when embodiments for solar prosumer buildings are considered. Urban emissions scenarios for Glasgow indicate about 20 MtCO2eq of urban consumption-based emissions in 2020 that are analyzed up to 2030 and 2050 under different decarbonization scenarios. Remaining urban emissions are linked to inefficiencies where exergy mismatches cause emissions responsibilities in the energy system. In comparison to the decarbonization index in the urban emissions scenarios for Glasgow, the increased exergy match at 0.87 is closest to its 2045-year value in the renewable energy based green-growth scenario. The results are useful for guiding other urban areas to embark on an effective approach for mitigation and bring society to a better balance with the planet. Districts and cities can utilize these metrics to upscale climate mitigation and minimize emissions more rapidly.