Exploring Synergistic GHG Emissions Mitigation Potential and Costs of Room Air Conditioners.

This study explores the potential of synergistically reducing direct (refrigerant) and indirect (electricity) greenhouse gas (GHG) emissions in the global room air conditioning (RAC) sector, based on 80% of global RAC manufactured in China. Three scenarios are evaluated: Business-as-usual (BAU) based on maintaining refrigerant and energy efficiency levels from 2021 China RAC sales shares, Kigali Amendment compliant with 10% energy efficiency improvement by 2025 (KAE), and accelerated refrigerant transition and energy efficiency improvement (ATE). Each scenario considers the costs of refrigerant and efficiency measures for export market groups based on Kigali Amendment classifications. BAU predicts around 1 Gt CO2-eq average annual global RAC emissions (2022-2060). Cumulative emission reductions in China's RAC manufacturing under KAE and ATE are 12.2 and 17.2 Gt CO2-eq A5II and A5I (except China), presenting cost-effective abatement measures, with average costs of -$51.4 and -$68.8/t CO2-eq in KAE and ATE. Cumulative average abatement costs are around $18 and $4/t CO2-eq globally. KAE and ATE scenarios would avoid surface temperature rises of 0.023 (±0.002) °C and 0.027 (±0.003) °C, respectively, versus BAU. Collaboration between China and importing countries is urged to enhance energy efficiency in RACs traded, ensuring sustainable mitigation aligned with the Kigali Amendment.

Atmospheric Observation and Emission of HFC-134a in China and Its Four Cities.

1,1,1,2-Tetrafluoroethane (HFC-134a) is widely used as a refrigerant to replace dichlorodifluoromethane (CFC-12), and a small amount of it is used in the foam and medical aerosol sectors, with a high global warming potential and fast-increasing atmospheric concentration. The emission of HFC-134a in China has been growing at an average annual growth rate of 14.4% since 2009, reaching 53.0 (47.5-58.7) kt yr-1 in 2020. Among the five emission sources, emissions from the mobile air conditioning (MAC) sector accounted for the highest proportion of 65% on average of the total, followed by the commercial air conditioning (CAC) sector (25%), the medical aerosols sector (8%), the foam sector (2%), and leakage emission from the production (less than 0.1%). The emissions of HFC-134a in four cities in China (Beijing, Guangzhou, Hangzhou, and Lanzhou) were also estimated and discussed. Beijing had the highest HFC-134a emission of 2.2 kt yr-1 in 2020, and Lanzhou had the lowest emission of only 0.2 kt yr-1. In Beijing and Guangzhou, emissions from the CAC sector surpassed those from the MAC sector, becoming the most important source of HFC-134a. The average annual growth rate of HFC-134a's emissions during 2009-2019 was close to its concentration enhancement growth rate of 12.7%, and the emissions also showed significant correlations with the concentration enhancements in both China and four cities. This indicates the importance of the muti-city and long-term observations for the verification of HFC-134a's emission estimates at a regional scale.

Pathway and Cost-Benefit Analysis to Achieve China's Zero Hydrofluorocarbon Emissions.

Global hydrofluorocarbon (HFC) cumulative emissions will be more than 20 Gt CO2-equiv during 2020-2060 and have a non-negligible impact on global warming even in full compliance with the Kigali Amendment (KA). Fluorochemical manufacturers (including multinationals) in China have accounted for about 70% of global HFC production since 2015, of which about 60% is emitted outside China. This study built an integrated model (i.e., DECAF) to estimate both territorial and exported emissions of China under three scenarios and assess the corresponding climate effects as well as abatement costs. Achieving near-zero territorial emissions by 2060 could avoid 23 ± 4 Gt CO2-equiv of cumulative territorial emissions (compared to the 2019 Baseline scenario) during 2020-2060 at an average abatement cost of 9 ± 6 USD/t CO2-equiv. Under the near-zero emission (including territorial and abroad) pathway, radiative forcing from HFCs will peak in 2037 (60 ± 6 mW/m2) with a 33% peak reduction and 8 years in advance compared to the path regulated by the KA, and the radiative forcing by 2060 will be lower than that in 2019. Accelerated phase-out of HFC production in China could provide a possibility for rapid global HFC abatement and achieve greater climate benefits.

Atmospheric observation and emission estimation of HFC-125 and HFC-32 in China from four representative cities.

HFC-125 and HFC-32 are fluorinated greenhouse gases of great concern due to their high GWPs and increasing background atmospheric concentrations. Long-term atmospheric observations of HFC-125 and HFC-32 were carried out in four representative cities of China (Beijing, Guangzhou, Hangzhou, and Lanzhou) from January 2012 to October 2019. Overall, the annual mean atmospheric concentrations of HFC-125 and HFC-32 both showed increasing trends, with average rates of 4.8 ppt yr-1 and 7.9 ppt yr-1. The average concentrations of HFC-125 and HFC-32 in urban areas were significantly higher than those in suburban areas. Significant differences in atmospheric concentrations of the two HFCs were observed among the four cities. HFC-125 and HFC-32 emissions were estimated accordingly, averaging 6.2 Gg yr-1 (23.6 Mt. CO2-eq) and 5.7 Gg yr-1 (4.3 Mt. CO2-eq) during 2012 and 2019 and growing at rates of 0.8 Gg yr-1 (3.1 Mt. CO2-eq) and 0.8 Gg yr-1 (0.6 Mt. CO2-eq), respectively, with an increasing contribution to global radiative forcing. The bottom-up inventories of HFC-125 and HFC-32 in the four cities increased annually from 2012 to 2019, with the highest emissions in Beijing, while the top-down emissions fluctuated during the research period. SYNOPSIS: The atmospheric concentrations of HFC-125 and HFC-32 were measured from 2012 to 2019 in four representative cities of China. Both HFC emissions at national and city levels were estimated using observation-based and inventory methods.