## 3 Model Development
### CO\({}_{2}\) Emissions and Energy Consumption Estimation
\begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Vehicle Types**} & \multicolumn{4}{c}{**CO\({}_{2}\) Emission Factors And Fuel Economy Factors**} \\ \cline{2-5}  & \multicolumn{2}{c}{**CO\({}_{2}\)**} & **R\({}^{2}\)** & **Fuel Economy** & **R\({}^{2}\)** \\ \hline Gasoline motorcycle (MC) & Y = 0.0169X\({}^{2}\) - 1.3909X + 57.674 & 0.80 & Y = \(-\)0.0149X\({}^{2}\) + 1.2391X + 37.895 & 0.68 \\ \hline Gasoline passenger car (PC) & Y = 0.0686X\({}^{2}\) - 7.7792X + 340.01 & 0.92 & Y = \(-\)0.0028X\({}^{2}\) + 0.3642X + 5.4924 & 0.98 \\ \hline Diesel pick-up truck (PUT) & Y = 0.0695X\({}^{2}\) - 8.0605X + 373.14 & 0.94 & Y = \(-\)0.0024X\({}^{2}\) + 0.3346X + 5.6714 & 0.98 \\ \hline Medium diesel bus (B) & Y = 1.955X\({}^{2}\) - 21.345X + 836.12 & 0.90 & Y = \(-\)0.0003X\({}^{2}\) + 0.1277X + 3.0026 & 0.97 \\ \hline Heavy diesel truck (T) & Y = 0.2889X\({}^{2}\) - 33.506X + 1493.7 & 0.93 & Y = \(-\)0.0011X\({}^{2}\) + 0.1238X + 1.6474 & 0.87 \\ \hline \hline \end{tabular}  
* Remarks: X = average traveling speed (km/h), and Y = CO\({}_{2}\) emission factors (g/km) or energy consumption rates (km/liter).  
\end{table} 
Table 3: The selected emission and fuel economy factors by vehicle type and engine technology, adapted from [48; 49]. \(EF_{grid}\) = The emission factor of grid electricity in the year \"\(y\)\". The CO\({}_{2}\) emissions from electric vehicles, both electric passenger cars (EPCs) and electric motorcycles (EMCs), are calculated based on the distance traveled (Equation (4)). The average energy consumption for an electric passenger car (EPC) is about 21 kWh/100 km. For an electric motorcycle (EMC), it is about 4 kWh/100 km. The electricity consumption for electric vehicles (EVs) is assumed to be constant throughout the modeling period. These figures represent the average urban electricity consumption values for medium-sized electric passenger cars and motorcycles available in Thailand. The assumed fuel economy of electric vehicles (EVs) aligns with the assumptions adopted in the Global EV Outlook [51]. The emission factors from electricity consumption are based on national grid emission factors provided by the Energy Policy and Planning Office [52], and future grid emission factors are based on the Power Development Plan (PDP) 2018, Revision 1 [53]. Declining grid emission factors reflect the national policy of increasing the share of renewable energy in power generation to meet Thailand's nationally determined contribution (NDC) target of reducing GHG emissions by 20-25% by 2030 [54]. However, the future grid emission factors in the PDP are provided up to the year 2037, the end year of the plan. The grid emission factors for the forward years are assumed to be the same as the year 2037. The grid emission factors of Thailand from 2016 to 2046 are shown in Figure 5.  
\[DPE_{EV,y}=[(PC_{EV,y}\times KT_{EV,y}\times EC_{EV,y})+(MC_{EV,y}\times KT_{ EV,y}\times EC_{EV,y})]\times EF_{grid,y} \tag{4}\]  
where:  
\(DPE_{EV,y}\) = Direct project emissions of electric vehicles in year \"\(y\)\" (tCO\({}_{2}\)/year);  
\(PC_{EV,y}\) = Number of electric cars in the year \"\(y\)\";  
\(MC_{EV,y}\) = Number of electric motorcycles in the year \"\(y\)\";  
\(KT_{EV,y}\) = Kilometre-travelled of electric vehicles;  
\(EC_{EV,y}\) = Electricity consumption for electric vehicles in the year \"\(y\)\" (assumed as a constant value, 21 kWh/100 km for electric cars and 4 kWh/100 km for electric motorcycles);  
\(EF_{grid,y}\) = The emission factor of grid electricity in the year \"\(y\)\".