The aim of the project we were involved in was to analyse the feasibility of implementing batteries to power trains for traction. As power failures often cause train breakdowns in Singapore, we were tasked to investigate how we could implement batteries power trains instead of relying on only electricity during emergencies. ideally, the batteries would continue services of the train, or at least bring to the next nearest station for passengers to alight during power shortages. At the point when we joined, the status of the project was only feasibility analysis. As such, we engaged research to suggest which batteries would be suitable for usage in trains, and to do relevant calculations to see whether it would be possible to use batteries for traction power.

Before we started, to gain some background knowledge, we read up on what system Singapore currently uses to power its trains and learnt that it uses the third rail system and overhead catenary system. We also looked at examples from other countries where they had implemented batteries into their trains, and saw that batteries were used for emergency purposes, or to pass non-electrified rails.

We had to decide on the scope of our project, in which we chose to focus on using batteries for emergency situations aka when there are times of power shortages, since this problem was the most prominent to train breakdowns. We focused on 2 scenarios, firstly to provide the train with enough traction power to move it to the next station so that passengers can alight, and secondly for service continuity in which the train completely bypasses an area of power shortage until it reaches an area with power supply to keep the MRT services ongoing.

Then, we researched on batteries available for commercial use, and we needed to see which battery had properties that were the most suitable for powering trains. Since we were looking for batteries that were had relatively high energy density and power output, long life cycle, good safety and performance, we ended choosing lithium-iron-phosphate (LFP) batteries for traction due to its high power output and safety, and lithium-nickel-manganese-cobalt-oxide (NMC) batteries for non-traction due to its high energy density required for keeping essential systems running for a longer period of time.

We did calculations to see the total weight of batteries required to power the trains, and space needed to hold the batteries. Our plan was to place the batteries on the underseat compartments on the train, which we found to be feasible since there was enough space to house the required amount of batteries and their accompanying systems. Subsequently, we also had to give suggestions on weight considerations, such as increasing the weight limit of the trains for changing infrastructure of the train.

Our potential solutions for existing trains were that traction batteries could be added for getting to the next station, with minimal changes needed to accommodate their weight, while for future trains, traction batteries for service continuity could be added, if weight limit for new trains are increased, or if trains are built lighter. We also suggested that new lines can also be designed to have non-electrified sections to take advantage of the batteries in the trains.

During this project we considered the economical impact of train breakdowns in Singapore, however due to lack of information it was hard to quantify it. Ultimately, we decided that whilst the reliability of trains has been improving, it might not be extremely beneficial, however, it would not hurt to take extra action to mitigate the inconveniences of train breakdowns.

The challenges of the project was that there was a lot of information to process during research, such as the many different types of batteries and their sub-categories. I had to read through a lot of content and at times it became confusing. We had to weigh the pros and cons of multiple battery types in order to make the best choice. Furthermore, since batteries have never been used for traction in Singapore, we did not have a lot of information readily available, which made our task more difficult.

Our deliverable at the end was to give a presentation on our analysis for usage of batteries in trains, which essentially consisted of the pros and cons of implementing batteries, and suggestions on alleviate the disadvantages of it.

From this project, I have gained much knowledge about MRT systems in Singapore, and I am now much more familiar with them. We also have successfully conducted our analysis of batteries in trains, and I have picked up skills on how to do productive research and give an organised presentation.

1) How to structure a presentation

While we were creating our presentation, I learnt more on how to make a presentation more concise and engaging. For example, when there is much information to be processed, in would be helpful to compress it into a table, so that it would be easier to read and compare with others. Another helpful tip was that relevant pictures can help brighten up the content on the slides to catch the attention of the audience effectively.

2) Different types of lithium-ion batteries

During this project, I learnt that there were many various types of lithium ion batteries, and each of them had differing properties. For example, lithium-titanium-oxide batteries are very safe, have long lifespans, charge fast and provide high power, but are expensive and have lower energy densities due to lower cell voltage, while on the other hand lithium-nickel-manganese-cobalt-oxide batteries have lower safety, shorter life cycles and provide more energy rather than power. While the two may be both categorised under li-ion batteries, they had different properties that suit different purposes.

3) How Singapore's trains are powered

Singapore currently uses these two system to power their trains, the third rail system and the overhead catenary system. The third rail is an additional rail placed alongside or between the rails of a railway track provides electric traction power to trains, and mostly supply direct current electricity. On the other hand, the overhead catenary uses a pantograph which presses against the underside of the contact wire to collect current, and allows current to flow through to the train and back to the feeder station through the steel wheels on the running rails.

1) A realistic aspect is that this project was a very researched focused one, hence a lot of time is spent on the computer and reading through various documents. This might be boring for those who do not have a passion for studying transport. However, I felt that the more I researched, the more interesting information I picked up and hence, the continuous stream of knowledge spurred me on in my learning. Furthermore, as there was a lot of content to digest, reading through all of it and picking out important and relevant parts to form a concise document was very rewarding. It was my first time studying about this subject, but it was fascinating and I had gained much knowledge.

2) Our analysis required us to consider methods which have not been implemented yet. Currently, battery standards for auxiliary power supply systems in railway application is only available for lead acid batteries and nickel cadmium batteries, however these batteries did not meet our expectations and hence we looked towards using lithium ion batteries instead, despite not knowing the exact requirements for it. We also considered using supercapacitors at one point despite it being not widely used it the railway industry.

We should also keep an open mind when doing anything. During this project, while the work we did was repetitive in nature, however keeping an open mind made we more willing to study all these content, and pushed me to delve deeper to find out more about the details. As such, this allowed us to consider various options on ways to power the trains, and not only stick to one method. For example, instead of using only one type of battery for all the functions, we decided to use two types, one for traction and one for non-traction. Instead of merely using methods that were already in place, exploring other types of ways which may not be as conventional, allowed us to discover the most optimal solution.