Railway to buy devices to cut fuel waste, emissions in diesel engines

The Bangladesh Railway will procure 40 small-capacity engines, which are expected to save 85% of the diesel consumed by locomotives while idling and reduce emissions by 94%.

Idling running time is highest for freight train engines, which spend an average of 10 hours a day idling at stations, each burning 20 litres of diesel per hour. This translates into an annual diesel waste worth about Tk72 lakh per locomotive during idling hours alone.

An auxiliary power unit (APU) can reduce fuel consumption to three litres per hour, thereby saving 60,588 litres and cutting carbon dioxide (CO2) emissions by 1.62 lakh kg per locomotive annually, according to an Asian Development Bank report.

The APUs will be purchased under the ADB-funded Railway Rolling Stock Improvement Project, which aims to enhance the railway's operational efficiency. The lender is also providing technical assistance to train railway drivers and officials on the new technology to maximise its benefits.

Train engines are typically kept running during long waiting periods at stations or in sheds to avoid the extended time required to restart with sufficient air pressure for the brake system. During prolonged waiting for traction, shunting, or stops, railway engines must remain operational to power the compressor and charge the batteries.

An APU can power all these auxiliary functions while consuming significantly less fuel and emitting minimal emissions, according to the ADB's final report on the technical assistance project.

"For instance, an assessment by Indian Railways showed that APU would consume 85% less diesel fuel than the main engines. The fuel savings will contribute to the reduction of carbon dioxide emissions and other pollutants like nitrogen dioxide and particulate matter," it reads.

The Bangladesh Railway operates a fleet of 328 locomotives over a total route length of 3,093km. More than half of its metre-gauge engines and a third of its broad-gauge engines have now surpassed their 20-year economic life, leading to increased fuel consumption.

Data from the Bangladesh Railway show that total fuel consumption rose to 48,300 tonnes in the fiscal 2022-23, up from 40,200 tonnes the previous year. This increase is attributed in part to the higher number and frequency of trains.

"APU reduces idling fuel consumption by 83% and hydrocarbon emission by 94%," the ADB says in its report, citing studies of Southwest Research Institute that find such a device can cut emissions of nitrogen oxide by 3.97 tonnes and carbon dioxide by 191 tonnes per year for a 2,000HP locomotive.

The railway uses powerful engines of 3,000-4,000HP for long-haul operations, leading to high fuel consumption and significant pollutant emissions. For a Bangladesh Railway engine that uses high-speed diesel, CO2 emissions could reach 2.67 kg per litre.

"The APU, even if installed in existing diesel engines, significantly reduces fuel consumption, which significantly reduces greenhouse gas emissions and can be a key component of efforts to mitigate climate change," it says, citing Bangladesh's climate pledge made with the Paris Agreement to improve fuel efficiency and cut emissions in transport.

As part of its commitment to climate mitigation, Bangladesh has pledged to cut vehicular emissions by 10% by 2030 and to promote a road-to-rail modal shift through schemes such as BRT, MRT, and multimodal hubs. The plan includes transitioning to electric trains and modernising rolling stock and signalling with energy-efficient technologies.

The ADB points out that Bangladesh Railway's strategic roadmap also recommends the use of APUs to reduce fuel consumption by locomotives while they are stationary or idling.

The payback period - i.e., the time required to recover the procurement cost – is estimated to be two years and three months for an APU, which has an initial cost of Tk1 crore, according to the lending agency.

Although the effectiveness of APUs is internationally proven, it is a new technology for Bangladesh. Proper operation is crucial to realising its full potential, as noted in the ADB report released in June 2024.

The report cites that neighbouring Indian Railways utilised only 43% of the potential APU hours due to inadequate operations by locomotive drivers, highlighting the need for training to maximise the benefits of APUs for the Bangladesh Railway.

The technical assistance project aims to train Bangladesh Railway officials and 100 locomotive drivers on handling APUs equipped with new technologies to improve the energy efficiency of Bangladesh Railway's rolling stock operations.