Feasibility analysis of harvesting dynamic brake energy in diesel-electric multiple units for sustainable operation in the Sri Lankan context

Abstract

Dynamic braking helps regulate train speed and avoids it from becoming too high, especially when they are going downhill. Sri Lanka's non-electrified railway system loses energy because Diesel-Electric Multiple Units (DEMUs) turn braking energy into heat. However, electrified railways recover and reuse braking energy. This study's goal is to perform feasibility study on the use of this wasted energy, which will make things more sustainable, lower costs, and lower carbon emissions. The first step of this study is to figure out how much energy is lost by S14 DEMUs running on Sri Lanka's upcountry railway line. Study looked at data from onboard loggers, circuit diagrams, operation manuals, and previous tests of the brakes. The results show that a 20-hour round trip from Badulla to Colombo dissipates about 3.5 MWh of energy. Additionally, dynamic braking intervals and patterns were identified to study on feasibility analysis. Feasibility analysis continued on sustainable energy recovery system to store and reuse a portion of this wasted energy for auxiliary power in the S14 DEMU without altering its existing structure. A Lithium Iron Phosphate (LFP) battery storage system was chosen because of its use in the past and in the railway and automotive industries. A 1 MWh battery pack was added to utilize 1.7 MWh where charging was best during the first 6.5 hours from Badulla to Gampola, where the brakes work best. The system is expected to save more than 105 million LKR and cut diesel use by 550,800 liters over a period of 10 years. This will lower emissions and support sustainability. These results point to a feasibility study that is cost-effective and will help make non-electrified railway networks more energy-efficient and environmentally friendly.