1 Introduction
Singapore is ranked first in Asia, and second globally as the most sustainable city. However, Singapore accounts for 0.12% of global greenhouse gas emissions. Singapore aims to achieve 36% reduction goal in carbon emissions intensity by 2030 (Feng, 2015).
Does it show a proportional, write it in terms of Asia or ranking? Carbon emission per GDP
Singapore’s transportation sector contributes 15.32% to the total greenhouse gas emissions in 2016 (Feng, 2015). While the usage of electric vehicle (EV) is one way to reduce greenhouse emissions, the country is facing challenges to fully embrace the usage of EVs as the main means of commute. Challenges such as the high cost of EVs, Singapore’s limited EV infrastructure and the considerable safety aspects of plug-in EVs generally deter local consumers and Singapore’s public transport operators to consider the switch to EV. According to Kuttan (2017), EV drivers are afraid of travelling long distances with the risk of their vehicle batteries running flat. He added that the accessibility of fast chargers is the only factor that will encourage people to be more open to conventional EV.
Today, Singapore’s buses dominantly run on natural gas and diesel. With greater awareness on environmental sustainability, the LTA will be buying 50 new hybrid buses and 60 new pure-electric buses (CNA, 2017). The K9 pure-electric buses which will be tested by Go-Ahead Singapore needs five to 10 hours charging time to travel 250 km. These buses emit no greenhouse gas emission or noise, thus reducing air and noise pollution. Their traveling distance, however, will be reduced due to the warm and humid climate in Singapore with additional battery power used for cooling (Lim, 2016).
E-buses have zero emissions, run quieter than conventional buses, contribute less to the carbon footprint, require less maintenance, and are much cheaper in the long run, as compared to diesel buses. However, long travel distances, high turnover rate of buses in Singapore, limited charging periods, and heavy battery requirements make electric buses unsustainable in Singapore. To eliminate these problems, the usage of wireless charging technology in e-buses can be implemented.
2 Problem statement
An ideal pure-electric bus system in Singapore should be energy efficient, self-sustainable, and has good accessibility to charging points. However, the K9 electric buses which is tested by Go-Ahead Singapore needs five to 10 hours charging time to travel 250 km, is reduced because of the warm and humid climate in Singapore with additional battery power used for cooling (Lim, 2016). With the implementation of a wireless charging bus system, this will improve the accessibility of charging while reducing charging time.
3 Purpose Statement
The purpose of this report is to outline to LTA the advantages of the wireless charging technology for electric buses which tackles the challenges in the current system, and propose to them to conduct a pilot study to test the wireless charging system.
4 Proposed Solution
The solution to this problem is to use wirelessly charged electric buses. ‘Wireless charging technology’ or power transfer through magnetic induction has been tested since the early 2000s on electric buses in several countries like Italy, China, USA, Japan and Korea. Inductive charging requires a charging station which has an induction coil in it. This then produces the electromagnetic field which transfers the energy across the gap to corresponding induction coil in the device. The device then converts the energy from the magnetic field back into a useable electrical current which is then used to charge the battery (Thomson, 2014). These buses receive power without physical contact unlike the conventional usage of electric cables for plug-in EVs. The charging process is thus simplified as buses need not be charged only in the bus depot or interchange but instead, charged on the go.
An example for this technology was tested by Korea Advanced Institute of Science of Technology (KAIST). This technology granted electric buses to be charged while in motion. It eliminates the need for remote static charging stations and introduces charging infrastructure embedded in the roads. As a result of charging on-the go, the company’s e-buses utilised smaller, inexpensive batteries which in turn reduced the vehicle weight. With a lighter load, the buses expanded less energy. Moreover, wireless charging plates could be built beneath the roads without having any impact on the cityscape.
4.1 Case Study
KAIST is the first in the world to introduce Shaped Magnetic Field in Resonance (SMFIR) technology that safely deliver energy to an electric vehicle wirelessly while vehicle is in motion. It was developed as part of KAIST’s online electric vehicle (OLEV) project. By having energy transferred, the OLEV transport system is wirelessly powered by underground coils without any mechanical contact. A pickup device installed under the vehicle works to gather the magnetic field efficiently from power grids embedded in the road and convert it into electric energy for vehicle operation. The pickup coils are tuned to a 20kHz resonant frequency and are modelled to have maximised exposure to the generated magnetic field, as a result, the efficiency of the magnetic power transmission can be maximized while decreasing the magnetic field leakage (Suh, n.d.).
Figure 1: Simplified concept of power transfer using SMFIR (KAIST, n.d.)
According to the article “KAIST OLEV Transport System,” the usage of the SMFIR technology yields a power transmission efficiency of 83% at a ground height of 20cm and a 75kW of power capacity. This was by far the most efficient wireless power transfer system available for commercial deployment to e-buses. With the provision of power supply infrastructure embedded on five to 15 percent of the whole bus route, it is sufficient to wirelessly powered OLEV bus for its operation. The power strips that supply OLEV buses with electric power have been installed at bus stations, bus stops and traffic junctions which allows the battery of the OLEV bus to be recharged. With the SMFIR technology, OLEV buses have reduced battery size of 20% compared to a normal electric bus. OLEV complies with the international electromagnetic fields (EMF) standards of 62.5mG which is within the safety margin for human health. Segment technology is introduced to control the power supply by switching on when it detects OLEV buses, hence, it distinguish OLEV buses from other vehicles. As a result, it will prevent EMF exposure and standby power consumption to other road consumers.
Figure 2: Overview of power supply infrastructure (KAIST, n.d.)
4.2 Application of OLEV in Singapore
While the idea of revamping the public bus system in Singapore into wireless may seem challenging, a pilot study can be first be conducted to assess the feasibility of the OLEV technology on Singapore’s public buses. As part of the engineering design and development process, a bus route can be selected within the Punggol Digital District to apply the power supply infrastructure. The route will operate a couple of OLEV buses over a 6km one-way trip, which will take approximately 20 minutes for each trip. The objective is to design the most efficient and optimized power supply infrastructure. This includes identifying how long the powered track should be, where it should be installed, and what combination of the segments should be laid. As a rule of thumb, the powered track should be installed where the driving power exceeds the battery discharge capacity, so that the buses can have a enough power to be driven.
4.3 Benefits of Proposed Solution
1. The implementation of the OLEV system helps to simplify the charging process without the need of anyone handling heavy charger cables and plugs. (KAIST, n.d.)
2. The system can virtually run 24/7 with the increased accessibility to wireless charging segments that ensures the buses to be charged without stopping. It also prevent chances of battery from running flat. (Brian, 2013)
3. The OLEV system can be extended to cars, lorries and other vehicles. The usage of wireless charging vehicles will reduce the amount of carbon emission making Singapore’s land transportation more eco-friendly. (Fischer, 2016)
4. With technology advancement, the cost of batteries will become cheaper than conventional EV batteries. This will promote EV uptake in the and this will provide cheaper replacement cost. (KAIST, n.d.)
5. OLEV weight of batteries will be lighter, allowing e-buses to use less power to move the bus and batteries will be more efficient which reduces the frequency to charge. (KAIST, n.d.)
6. The need to build expensive recharge facilities can also be eliminated. This will reduce the space efficiency which can be put to other use. (Suh. I. S., n.d.)
7. This system significantly allows batteries to be smaller and reduces the amount of lithium used. (Whitlock, 2016)
8. OLEV technology ensures safety with their OLEVs and supplies it with electric power through pickup devices build under the vehicle’s body. (KAIST, n.d.)
9. The success of the system entails a promising return for Singapore to pioneer the advancement of electric vehicle systems in the tropics.
10. OLEV technology can be incorporated into autonomous vehicles to achieve Singapore’s 2030 Smart Nation goal.
11. A virtual fossil fuel-free urban transportation can be achieved with the increase in electric vehicle uptake and improved charging system and infrastructure.
4.4 Evaluation of Proposed Solution
1. The exact proposed locations of charging segments on Singapore’s roads have to be further considered and studied. Proposed locations could be the bus depots, bus stops and traffic junctions. These locations are ideal for charging e-buses but traffic junctions necessitate the usage of the GLIDE system which detects the presence of vehicles and pedestrians at the junctions of major roads. Little is known about the effect of magnetic coupling on the GLIDE system’s wire sensors.
2. The unpredictability of traffic conditions may cause buses to run out of power before reaching the nearest charging strip.
3. Given that Singapore would be the first tropical country to test wirelessly charged buses using the OLEV technology, little is known about its performance as Korea where this system had been tested is non-tropical climate.
4. It is challenging to pick a suitable bus route to work well with the bus as it determines the distance of the bus stops and to obtain maximum efficiency.
5. It will be hard to ensure drivers do not sway while driving on the road as the induction coil will be placed at the center of the road.
6. With the current technology, battery prices are still expensive and bulky which might bring conflict to the project.
5 Methodology
5.1 Primary Research
Primary research in the form of interviews were conducted with SIT-UoG’s Deputy Programme Director for Civil Engineering, Dr. Kum Yung Juan, and SIT’s Programme Director for Telematics (Intelligent Transportation Systems Engineering), Dr. Zheng Jianxin. The interviews enabled the team to gain insights and opinions from experts on electric vehicles and the feasibility of the wireless charging system for electric buses. The interview transcript with Dr. Kum and the summarised interview with Dr. Zheng can be found in Appendix A.1 and A.2 respectively.
5.2 Secondary Research
Online sources are used for the information of the different wireless charging technologies tested in other countries. After evaluating the different technologies, the OLEV technology by KAIST has been widely quoted in this report due to its extensive design information and its feasibility as a solution to the problem mentioned.
6 Conclusion
To conclude, the implementation of wirelessly charged e-buses for Singapore’s public bus system could be one way to solve the problems associated with electric buses, and potentially be a game changer in electric vehicle uptake. It will, however, take time for the pilot study to be completed and evaluated before LTA decides to implement the system fully into Singapore’s roads, and observe large-scale benefits to the economy, environment and local consumers.
Reference
Brian, M., (2013, August 7). Electric avenue: Korean buses now wirelessly charge as they drive. Retrieved from: https://www.theverge.com/2013/8/7/4596898/korea-wireless-charging-buses-kaist-olev
Fischer, M. (2016, July 7). Scandinavia’s first electric bus with wireless fast charging. Retrieved from: https://news.vattenfall.com/en/article/scandinavia-s-first-electric-bus-wireless-fast-charging
KAIST. (n.d.). KAIST OLEV Transport System. KAIST. Retrieved from: http://www.smfir.co.kr/20120323/sub02/KAIST_OLEV_en.pdf
Kim, D. J., (2015, May 15). Wireless Charging Electric Bus. Retrieved from: https://kmatrix.kaist.ac.kr/wireless-charging-electric-bus/
Lim, A., (2016, August 6). E-bus to ply public route in trail lasting six months. Retrieved from: http://www.straitstimes.com/singapore/e-bus-to-ply-public-route-in-trial-lasting-six-months
National Environment Agency. (2016). Singapore second biennial update report 2016. Retrieved from http://www.nea.gov.sg/docs/default-source/energy-waste/climate-change/second-biennial-update-report-(16-dec-2016).pdf
One Motoring, (n.d.). Green Link Determining (GLIDE) System. Retrieved from One Motoring Web site: https://www.onemotoring.com.sg/content/onemotoring/en/on_the_roads/traffic_management/intelligent_transport_systems/glide.print.html
Suh, I. S., (n.d.). Application of Shaped Magnetic Field in Resonance (SMFIR) technology to future urban transportation. Retrieved from: http://www.buspress.eu/wp-content/uploads/2013/08/CIRP-Design-2011-Paper34-Suh.pdf
Suh, N. P., Cho, D. H., & Rim, C.T., (n.d.). Design of On-Line Electric Vehicle (OLEV). Retrieved from: http://www.springer.com/cda/content/document/cda_downloaddocument/9783642159725-c1.pdf?SG
Thomson, K. (2014, August 29). Problems with Wireless Charging. Retrieved from: https://cambrionix.com/blog/problems-with-wireless-charging/
Whitlock, R. (2016, February 26). Wireless energy transfer strips for electric vehicles and buses. Retrieved from: https://interestingengineering.com/wireless-energy-transfer-strips-for-electric-vehicles-and-buses
umar abdul aziz 