The potential challenge for the effective GHG emissions mitigation of urban energy consumption: A case study of Macau

Greenhouse gas (GHG) emissions from energy consumption have become a major focus all over the world. Cities, especially, are playing an important role in responding to the challenges of global climate change. However, there is still a lack of case studies on the whole life stage (including energy import, production, and consumption) at the city level. This is the first study to systematically estimate the whole lifecycle GHG emissions of urban energy consumption in Macau using the life cycle assessment (LCA) method. It identifies the main contributors, draws the balance framework diagram of energy GHG emissions, and proposes the effective reduction measures through a scenario analysis. The results show that the total GHG emissions of energy consumption in Macau increased from 2.10 x 103 kt CO2 eq. in 2000 to 5.34 x 103 kt CO2 eq. in 2018. In 2018, the energy-related GHG emissions in the import phase, production phase, and consumption phase were 3.37 x 103, 4.08 x 102 and 5.34 x 103 kt CO2 eq., respectively. Since the return of Macau from Portugal to China (December 20, 1999), its GHG emissions from energy import have come to depend more on Mainland China, increasing from 71% in 2000 to 98% in 2018. For the consumption phase, indirect GHG emissions are more important, accounting for 75.3% of total GHG emissions in Macau. From the final consumption perspective, the gambling industry results in the largest GHG emissions (38.07% in 2018), followed by the transportation industry; while for the final energy consumption types, electricity consumption has become the predominant source. The scenario analysis shows that under an ideal scenario, the GHG emissions can be slowed down and will peak in 2033.

Automated summary

This study is the first case study using the life cycle assessment method to estimate the entire life cycle greenhouse gas emissions of urban energy consumption in Macau. The results show that the greenhouse gas emissions from energy consumption in Macau have been increasing, with energy import and consumption being the main contributors. The study also proposes effective reduction measures.