Integrated approach for the estimation of regional low carbon potential: Application for Ho Chi Minh City, Viet Nam
Authors:   Department of Environmental Engineering International University – Vietnam National University Ho Chi Minh City, Tran Thanh-Tu , Nguyen Phuong V.H. ,   Faculty of Biology and Environment Ho Chi Minh City University of Food Industry, Ochi Yuki ,   E-konzal consultant company, Nishinakajima, Yodogawa, Osaka, Japan
Published: January 2024

Currently, multidisciplinary integrated and quantitative methodologies are necessary for policymakers in deciding a reasonable and acceptable target of greenhouse gas (GHG) reduction as well as realization of mitigation actions. Therefore, this study aims to develop an integrated methodology to harmonize the top-down and bottom-up approaches to support the development of low carbon actions at the regional or city level based on their energy-saving programs and technology status. This integrated approach is necessary to bridge the theoretical and empirical frontiers of modeling in quantifying and analyzing the feasibility of the local police framework and international cooperation in terms of climate mitigation projects. The top-down approach uses the Extended Snapshot (ExSS) tool to estimate GHG emissions and reduction potential based on macro socioeconomic information. Meanwhile, the technology-based bottom-up approach is a method to estimate the reduction potential of GHG emissions by accumulating specific energy-saving projects. Parameters related to energy service demand, energy efficiency, energy share, and dispersed power generation are harmonized in the integration process via a set of equations. Under the assumption of socioeconomic growth of Ho Chi Minh City (HCMC), which is a 1.37 times increase for population and a 4.41 times increase for GDP growth in 2030 compared to 2013, the total energy consumption will increase 3.73 times compared to 2013, which is nearly 26 million toe (Mtoe) in 2030. The total GHG emissions will also increase 4.02 times, reaching nearly 117.2 MtCO2eq if HCMC does not consider any climate change mitigation actions. However, if HCMC successfully implements the mitigation projects discussed and quantified in this study, the total GHG emissions might be lower, approximately 85.6 MtCO2eq. Analysis of the results from the two scenarios (BaU and CCAP) shows that the energy saving potential is approximately 15.0% and that the total GHG emissions reduction potential of HCMC (excluding the potential from grid power, which is outside the effort of HCMC) is 20.7% of BaU’s emissions, which is between the 8-25% reduction target of Vietnam intended nationally determined contribution. By looking at the disaggregation of reduction potential by each sector and project, policymakers can prioritize mitigation measures to meet the GHG emissions reduction target or to maximize GHG emissions reduction potential. The integrated approach requires the consistency between classifications in top-down (driving force based) and bottom-up (technology based) approaches as well as the modification and bridging of the top-down sectors and the bottom-up categories with detailed data. This method is very applicable for cities or regions that are developing climate change action plans with precise technological information.