Electric trains are ideal for commuter rail service with frequent stops. However, railway electrification is often applied to heavily-used routes where the density of traffic movement is sufficient to justify the high fixed costs. This is the main reason why there are still existing non-electrified commuter train routes being served by diesel trains. Tanzania Railways Limited operates a diesel commuter train on a 12 km route. Unfortunately, high fuel cost has been a challenge causing the train to operate at a loss. In this paper the potential of battery electric multiple units to replace diesel commuter trains and hence reduced fuel cost, has been studied. Compared to the Tanzania Railways Limited diesel commuter train, the battery electric multiple unit was found to reduce fuel cost by 79%.