Prospects for Emission Reduction in Vietnam Projected through a Bottom-Up Emission Inventory Approach

利用排放清單的方法,預視越南未來减排的前景與空間

Student thesis: Doctoral Thesis

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Award date18 Jan 2021

Abstract

In Vietnam (VN), regulations for the reduction of greenhouse gases (GHGs) emission and short-lived climate pollutants (SLCPs) in different sectors have been emphasized, particularly to comply with the Paris agreement (i.e., COP21) signed in 2015 by the VN government. To evaluate the prospects for emission reduction, it is necessary to estimate the status of existing emissions from particular sectors. Among different sources, thermal power plants (TPPs) and road transportation substantially contribute to VN emissions, which is increasing rapidly. This study develops an updated emission inventory (EI) for VN using a bottom-up approach, considering local activity data for TPPs and road transportation sectors, which is indispensable to evaluate current emission status and project future emissions. Based on the updated EI, this study evaluates the influences of regulatory control and renewable energy interventions on future emissions and estimates the potential for emission reduction in VN.

Through a bottom-up approach, updated EIs (for 2010, 2015, and 2019 base year) on TPPs were developed for multiple emission species (SO2, NOx, CO, NMVOC, PM10, PM2.5, BC, OC, CH4, and N2O). Local activity data, emission factors (EFs), and emission control efficiencies were accounted for to estimate the annual emissions of individual TPPs. Considering all emission control activities in the TPPs, the estimated emissions of SO2, NOx, and PM were ~20-70% lower than existing EIs. The annual emissions of coal-fired TPPs were the highest among TPPs. The largest uncertainty occurred in NOx, with ranges between -23.6% to +30.6% in 2015. In terms of regional distribution, the significant emission contribution was from the Red River Delta region for most of the emission species due to coal-fired TPPs. This study shows that the net GWP of emission in 2019 was 152.13 Tg CO2e in 20-yr time horizons, which has been increased by 79% compared to 2015. In the net GWP of emission, GHGs were >95% both in 2019 and 2015, with the highest from CO2 (~95%). Among the SLCPs, the contribution was the largest from NOx (7-8%). From 2010 to 2015, emissions growth rates were between +11.8% to +117%, while ~19% reduction in SO2 was found due to the decommissioning of oil-fired TPPs. During 2015-2019, emissions growths were between +33.1% to +112%, as the number of TPPs have increased from 36 to 43. However, SO2 and NOx emissions from TPPs declined significantly after 2015 due to the progressive implementation of pollution control measures. A significant SO2 emission reduction has been observed with the revised emission control regulation compared to the 2015 emission control level (i.e., 74.86 vs. 48.58 Gg). Compared to the 2019 base year, the future emission of pollutants from TPPs is projected to increase significantly during 2020-2030, with the largest share from the coal-fired TPPs. However, the study shows that emission is expected to reduce considerably under the emission control scenarios due to the proposed implementation of the modern emission control system in all coal-fired TPPs, as a significant regulatory measure in the power generation sector in VN. For instance, NOx emission is expected to reduce noticeably in 2030, which is interestingly like the 2019 base year emission (i.e., 247.62 Gg vs. 279.53 Gg) as indicated by the study. 

This study develops a new national road transportation EI for VN. It also estimates the contribution from two rapidly growing cities (Hanoi and Ho Chi Minh (HCM)) to the national road transportation emission. Vehicle population data of different vehicle classes, annual vehicle kilometers traveled (AVKT), and EFs relevant to vehicle classes were used for emission estimation. Additionally, technological improvement and changes in vehicle fuel standards have been considered as the necessary corrections in emission projection. Results show that the total CO emissions from all vehicle classes were the highest in all base years, which has increased considerably during 2010-2019, with the annual growth rate of ~11%. Motorcycles (gasoline-powered) contributed a substantial level of CO, NMVOC, CH4, PM2.5, PM10, OC, and N2O (⁓53%-89%) in 2019, while NOx, BC, SO2, and CO2 were more from trucks (36.5%-76.3%). The emission share of pollutants to the total annual emission in 2015 was similar to 2019. The average emission contribution from Hanoi and HCM to the national road transportation emissions was ~14% and ~18%, respectively, during 2010-2019. The net GWP of emission in 2019 was 159.3 Tg CO2e, which increased by ⁓145% compared to 2010. Among the GHGs, GWP of emissions was the largest from CO2 (93.3%), while among the SLCPs, the largest was from BC (50.3%). Like TPPs emission projection, emissions of pollutants from the road transportation sector in the projection years are expected to increase compared to the 2019 base year. Compared to 2019, the emission growth rate of SLCPs and GHGs in 2030 ranges from 83% to ~121% and 85.5%-101.3%, respectively, under the Business-as-Usual (BAU) scenario. However, the emission of pollutants is expected to reduce considerably if the regulations could be implemented, as planned by the VN government. The total GWP of emissions (CO2e) might reduce ~23% to ~50% and 6.4% to ~73% for GHGs and SLCPs, respectively, under the mitigation scenario (i.e., MITI-2) in 2030 compared to the BAU projection.

Finally, this study demonstrates that in the future, renewable energy interventions (e.g., solar power to electricity and municipal solid waste-to-electricity) might significantly reduce GWP of emission (CO2e) in the thermal power sector in VN, replacing fossil fuel-derived electricity. It indicates a significant step towards the commitment made in the Paris agreement by the VN government. As projected for 2030, total electricity generation potential from solar power could range between 8,221 GWh to 14,200 GWh under different scenarios, with the best estimate of 11,211 GWh. In contrast, the total electricity generation potential from MSW could range between 8,585-18,342.2 GWh under various scenarios, with the best estimate of 12990.7 GWh. The study also shows that potential emission reduction in TPPs using solar power could range between 9,504-16,415 Gg CO2e under different scenarios in 2030, with the best emission reduction potential of 12,959 Gg CO2e. Based on the LCA perspective, potential emission reduction in TPPs using MSW-to-electricity strategy could vary between 987.3-9,684.7 Gg CO2e as estimated under different scenarios in 2030, with the best emission reduction potential of 4,910.5 Gg CO2e.