Regional variations in the health and environmental benefits of wind and solar generation: A case study of Vietnam

<span style="font-weight: 400;">When wind or solar energy displaces coal-fired power plants, the resulting health, environmental, and climate benefits depend on the characteristics of the displaced plants. Using data on plant-level emissions for 25 operating coal stations (27,134 MW), Monte Carlo&ndash;simulated hourly coal generation (N = 10,000), and synthesized hourly output from Vietnam&rsquo;s 21.6 GW installed solar and wind portfolio, I calculate the marginal displacement factors (MDFs) for CO</span><span style="font-weight: 400;">2</span><span style="font-weight: 400;">, SO</span><span style="font-weight: 400;">2</span><span style="font-weight: 400;">, NO</span><em><span style="font-weight: 400;">x</span></em><span style="font-weight: 400;">, and PM</span><span style="font-weight: 400;">2.5</span><span style="font-weight: 400;"> of the North, Central, and South regions of Vietnam. The North contains 43% of coal capacity &ndash; including the dirtiest plants &ndash; but receives only 3.7% of renewable generation. The CO</span><span style="font-weight: 400;">2</span><span style="font-weight: 400;"> MDF ranges from 1,139 kg/MWh in the North to 585 kg/MWh in the South, a ratio of nearly 2:1. When all four pollutants are monetized, each MWh of renewable energy displacing coal in the North avoids $93.7 in damages, compared to $55.4 in the Central region and $59.2 in the South. Vietnam&rsquo;s current renewable energy facilities avoid an estimated $1.36 billion in total damages per year ($60/MWh), with CO</span><span style="font-weight: 400;">2</span><span style="font-weight: 400;"> accounting for 74% of the monetized benefit. These results are robust to alternative dispatch assumptions (&plusmn;6 %) and emission-rate uncertainty (&plusmn;15&ndash;26%), though sensitive to the social cost of carbon ($0.75&ndash;$4.10 billion/yr across $20&ndash;$190/tonne). The findings imply that renewable energy siting decisions, inter-regional transmission planning, and coal retirement ordering should account for the geography of displacement benefits. Furthermore, this paper demonstrates that Siler-Evans&rsquo;s research approach can be applied to data-constrained and coal-dominated power systems in developing countries such as Vietnam, where the benefits of renewable displacement are significant but not well quantified.</span>