Emissions reduction and benefits of the first 3,825 electric buses under PM-eBus Sewa

Although buses constitute just 1% of the vehicle population in India, they contribute approximately 15% of total carbon dioxide (CO₂) emissions from transportation. To help address this, the Ministry of Housing and Urban Affairs (MoHUA) initiated the PM-eBus Sewa scheme, which aims to deploy 10,000 electric buses (e-buses) across 100 cities with populations exceeding 300,000. In December 2023, Convergence Energy Services Ltd. (CESL) issued the first tender under the scheme, and it aggregated demand for 3,825 buses across 49 cities. As these e-buses are expected to be deployed soon, let’s approximate the greenhouse gas (GHG) and tailpipe pollutant emissions avoided by their deployment compared with conventional diesel buses.

The ICCT supported the MoHUA in the PM-eBus scheme and back-of-the-envelope calculations such as these help us understand the environmental benefits of e-buses. Following this list of our assumptions is a table with the specifications of the e-buses modeled:

• If not for the PM-eBus Sewa scheme, the 49 cities would have deployed diesel buses.
• The fleet constitution is the same as the current CESL tender, in other words, 12 m air-conditioned (A/C) e-buses would be deployed on routes that would have been otherwise served by 12 m diesel buses, 9 m A/C e-buses would be deployed on routes served by 9 m diesel buses, and so on.
• GHG emissions are estimated for the use phase of the vehicle, for a lifetime of 12 years from 2023 to 2035. For diesel buses, these are tailpipe exhaust emissions. For e-buses, the tailpipe emissions are zero and we estimate the emissions from generating the electricity to charge the buses.
• The grid emissions are calculated under three scenarios: The future grid mix based on India’s stated policies from the International Energy Agency’s (IEA) Stated Policies Scenario (STEPS); a more ambitious shift to renewable energy under IEA’s Sustainable Development Scenario (SDS); and a 100% renewable electricity scenario.
• This analysis of use-phase emissions is the same as the use-phase emissions assessed in a full life-cycle emissions comparison performed in a previous ICCT study in India.

Table. Assumed specifications of e-buses deployed under the CESL tender

*Because no bids were received in the first tender, the 7 m buses were re-tendered with the second tender issued by CESL. These buses are thus expected to be deployed under the second phase of bus deployment.

Energy efficiency and emissions reduction 

Under our assumptions, e-buses are about 70% more energy efficient than diesel ones. Hence, even with the future development of India’s electrical grid under the STEPS scenario, which includes heavy reliance on coal, e-buses show a 19% reduction in use-phase GHG emissions over a vehicle lifetime from 2023 to 2035 compared with diesel buses (Figure 1). Additionally, although a diesel bus’s emissions are mostly locked in for its operational lifetime, the emissions from an e-bus will decline as the grid becomes greener. E-buses would reduce GHG emissions by 34% if the power grid transitions toward renewable sources like solar and wind under the SDS. In the scenario with 100% renewable energy powering the grid, we estimate e-buses have the potential to achieve a 96% reduction in emissions compared with diesel buses (the remaining 4% emissions are due to upstream emissions from renewable energy infrastructure estimated at 35g CO₂e/kWh).  

Figure 1. Estimated use-phase emissions from 3,825 buses over 12 years of life

The transition to e-buses not only curbs GHG emissions but also eliminates tailpipe pollutant emissions of nitrogen oxides (NO_x), sulphur dioxide (SO₂), carbon monoxide (CO), hydrocarbons (HC), and particulate matter (PM). Nitric oxide, nitrous oxide, nitrogen dioxide, and CO all contribute to the formation of secondary pollutants like ozone, nitric acid, and others. When combined with organic compounds, these pollutants can also create photochemical smog. NO_x and SO₂ contribute to acid rain. 

For the first 3,825 e-buses under the PM-eBus Sewa scheme, we project over 1,200 tonnes of NO_x emissions and 700 tonnes of CO avoided (Figure 2). To give a sense of the impact of this, research in Brazil suggests that decreasing NO_x concentrations in medium-sized cities by 3 micrograms per cubic meter can lower the risk of respiratory disease-related deaths by 10%–18%. Hence, e-buses are not just a win for the environment but also for public health. With its initiative, the MoHUA is not just encouraging public transport-centric urban development but also investing in creating healthier cities. 

Figure 2. Estimated tailpipe pollutant emissions avoided by 3,825 e-buses during 12 years of operation

Economic and social benefits 

Beyond environmental and health benefits, e-buses can offer economic advantages such as lower operational and maintenance costs. Such financial flexibility could allow transport authorities to invest in further planning and innovation. Moreover, the Government of India projects that the PM-eBus Sewa scheme will generate as many as 55,000 jobs. It will also contribute to energy security by reducing dependency on imported fossil fuels. 

It’s also notable how the MoHUA developed and executed this scheme. Although electrification of transport has traditionally been under the purview of the Ministry of Heavy Industries (MHI), this scheme saw inter-ministerial collaboration that aided in its execution. Such collaboration is also reflected in two separate instances: The recently announced “PM-eBus Sewa-Payment Security Mechanism (PSM) scheme” by MHI, which has an outlay of ₹3,435.33 crore to aid procurement of 38,000 e-buses, and under PM-eBus Sewa scheme implementation, where the Ministry of Power’s support for evaluating behind-the-meter infrastructure requirements was crucial in estimating the depot electrification costs for the e-bus depots being developed under PM-eBus Sewa. The ICCT looks forward to continuing a productive partnership with the MoHUA to pave the way for cleaner, more efficient, and sustainable urban mobility solutions in India.