CNG and diesel urban buses in India: A life-cycle cost comparison

Delhi’s bus fleet is powered by compressed natural gas (CNG) to address poor air quality. CNG has also been implemented in buses in other Indian cities. We evaluate the life-cycle costs (LCCs) of the Standard (high-floor), low-floor, and low-floor air-conditioned CNG buses and their diesel counterparts in India. Given the importance of fuel economy and fuel price for fuel costs, we analyze the sensitivity of the LCCs to these factors. Also, to assess the effect of fuel prices if they were market driven, we evaluate the LCCs of low-floor air-conditioned CNG and diesel buses in India, but with US fuel prices. Our study aims to inform decision-making regarding the implementation of CNG buses, in concert with an assessment of their environmental and health benefits. The LCCs for CNG are higher than for diesel, but CNG negatively affects the LCC of Standard buses proportionately more than for the low-floor buses. The LCC is significantly higher for the low-floor air-conditioned, relative to that of the low-floor, and in particular the Standard, CNG buses. The significantly higher LCCs for the low-floor and low-floor air-conditioned buses, even for diesel, raises the questions of whether these buses are justified by increased patronage, and how they affect transit supply and affordability. The fuel price and fuel economy of CNG are critical for the competitiveness of CNG relative to diesel buses. This, along with the wide variation in CNG and diesel prices, demonstrates the need for careful fuel pricing policies when CNG is implemented in bus transit

Operational and financial performance of Delhi\u27s natural gas-fueled public bus transit fleet: A critical evaluation

Following a Supreme Court of India directive, the bus fleet of the Delhi Transport Corporation (DTC) was converted to run on compressed natural gas (CNG) from around 1999 to 2000, to address the city\u27s air pollution. We critically evaluate the operational and financial performance of DTC\u27s bus fleet from 1989–90 to 2010–11 – that is, from ten years prior to CNG implementation until 10 years after – to assess how this performance was affected by the fuel switch, as well as the introduction of low-floor CNG buses. CNG implementation caused a significant reduction in the capacity to deliver transit service at DTC in the initial stages of the fuel transition. Also, it necessitated investments in buses at a considerable cost premium relative to their diesel counterparts. Operating costs per kilometre grew, due to increased fuel expenditures per kilometre, because of the lower fuel economy, and increased maintenance costs and breakdowns per kilometre, on the CNG buses. These costs were further exacerbated by the introduction of the low-floor CNG buses. Despite increased capacity due to the investments in the CNG buses, passenger-kilometres generally declined over our analysis period. As a result, operating costs per passenger-kilometre, and the ratio of operating costs to traffic revenues, have progressively worsened. We conclude that the financial situation resulting from these effects due to CNG implementation may have detracted from the ability to enhance transit capacity and provide transit service overall. Our study also demonstrates the need to analyze policies such as CNG implementation broadly, in terms of conflicts and trade-offs between environmental, and other (transit operation, socio-economic and equity) objectives, rather than narrowly in terms of only environmental outcomes

Cost-effectiveness analysis of compressed natural gas implementation in the public bus transit fleet in Delhi, India

Buses in Delhi have been fueled by compressed natural gas (CNG) since 2000, at significant expense, to improve air quality. We evaluate the emissions impacts and cost-effectiveness of CNG buses relative to diesel, in the early 2000s, and more recently – given stricter vehicle emission standards – in Delhi, and the Indian context. We also analyze the hypothetical use of cleaner diesel buses, instead of CNG, in the early 2000s. We consider health critical and greenhouse gas emissions, and capital, operating and maintenance costs, over the service life of buses. A scenario analysis is conducted to assess bus fleet emissions due to the higher costs of CNG buses resulting in some trips being shifted to diesel buses, or other modes. CNG buses in the early 2000s significantly reduced particulate and greenhouse gas emissions, relative to the diesel buses they replaced, and also cleaner diesel buses complying with more stringent BS-III/IV standards. However, cleaner diesel buses would likely have produced emission reductions with similar or better cost-effectiveness ratios relative to CNG. The emission reductions due to low-floor BS-III/IV compliant CNG buses relative to their diesel counterparts, during 2010–2015, were lower, with worse or similar cost-effectiveness ratios, compared with CNG buses relative to diesel in the early 2000s. The scenario analysis revealed that, under a budget constraint, it is preferable to remove diesel buses, and allow other motor vehicles to meet any shortfall in CNG bus supply, strictly from a particulate and nitrogen oxide emissions perspective. So, allowing only CNG buses to operate in Delhi was an effective policy choice in the early 2000s for mitigating local air pollution. We finally explore the implications of our results for mitigating emissions from bus fleets in Delhi and other Indian cities going forward