# Overview of Clean Automotive Thermal Propulsion Options for India to 2030
## 3 Methodology
### CO\({}_{2}\) Calculation Methodology  
In some of the technologies, the percentage CO\({}_{2}\) reduction was already available and was implemented in calculating the reduction of CO\({}_{2}\). The reference CO\({}_{2}\) g/km limit was considered as 113 CO\({}_{2}\) g/km as implemented in the Bharat Stage VI standards from the year 2020 as per the report on LDV Fuel Economy Standards [55]. The reference vehicle data considered in calculating the emissions by implementing the technologies are shown in Table 1 below. The diesel fuel density was considered as 0.84 kg/L (840 kg/m\({}^{3}\)), however as suggested by [56], the diesel fuel specifications for emission norm BS VI allows for 820-860 kg/m\({}^{3}\), therefore 0.84 kg/L was considered for the calculations. The carbon emissions from the vehicle were calculated by following the steps [57] outlined below: \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Vehicle Make**} & **Engine Capacity** & **Fuel Used** & **Fuel Density** & **Fuel Consumption** \\  & **(Litres)** & & **(kg/L)** & **(L/100 km)** \\ \hline Lotus & 1.6 & Diesel & 0.84 & 4.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Vehicle Base Configurations. Step 1: Calculating weight of carbon present per litre of fuel  
\[\text{A (g)}\times\text{B (\%)}=\text{C (g)} \tag{1}\]  
Step 2: Calculating CO2 emitted by combusting per litre of fuel  
\[\text{D (g)}+\text{C (g)}=\text{E (g)} \tag{2}\]  
Step 3: Calculating CO2 emissions from the average fuel consumption. \[\frac{\text{F (L/100 km)}\times\text{E (g)}}{100}=\text{G (CO2 g/km)} \tag{3}\]  
where,  
A = weight of 1 L diesel (g)  
B = carbon in diesel (%)  
C = weight carbon per litre (g)  
D = weight of O2 needed to combust carbon (g)  
E = weight CO2 per litre (g)  
F = Fuel consumption (L/100 km)  
G = CO2 emissions (CO2 g/km)  
The calculations of CO2 reduction based on fuel consumption carried out for waste heat recovery, advanced boosting and regenerative braking were carried out on the basis of fuel consumption, whereas split cycle engine, carbon capture, and storage, and advanced combustion technologies carbon reduction was calculated on the basis of the carbon reduction percent available through published research data. The calculations for each technology on the basis of fuel consumption is given below in Table 2.  
The calculations of CO2 reduction for every technology based on the percentage of CO2 reduction are as given in Table 3. The percentage reduction from each technology with corresponding minima and maxima were considered in order to plot the CO2 reduction graph. However, the technologies were considered upon the advancement of each technology in the country or the technology improvement in the current scenario. \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Enities** & **WHR** & **Adv. Boost** & **Regen. Braking** & **Reference Engine** \\ \hline
1 L Diesel (g) & 840 & 840 & 840 & 840 \\ \% Carbon in Diesel & 86.2 & 86.2 & 86.2 & 86.2 \\ Carbon in Diesel (g) & 724 & 724 & 724 & 724 \\ Oxygen Needed To burn Diesel (g) & 1920 & 1920 & 1920 & 1920 \\ CO2 gram per 1 L & 2644 & 2644 & 2644 & 2644 \\ Fuel Consumption L/100 km & 4.23 & 4.4 & 4.5 & 4.7 \\ CO2 g/L based on fuel consumption & 112 & 116 & 107 & 124 \\ CO2 \% Reduction compared to Ref. Engine & 10\% & 6\% & 14\% & - \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Calculation of CO2 Reduction through Fuel Consumption. The historic emission graph that shows the emissions produced due to transport vehicles in India, went down from 24% to 11% since 1971 to 2014. This drop is depicted in the graph below inspired by [59]. However, the emissions in India has increased but the graph plotted shows that the CO\({}_{2}\) emissions in transportation have gone down by 13% in the span of 44 years. The graph for transportation emissions that is plotted consists of total transport emissions including Automotive, Railway, Aerospace, et al.