The Use of Supercapacitor in Electric Vehicles

Background

Currently, about one quarter of world energy-related CO2 emissions caused by transport. With the increasing demand of mobility, that number will become even worse especially in developing countries. According to research, transport will release about 33% of global GHG emissions by 2050 (The World Bank, 2016). Because of the increasing amount of GHG emissions, the global temperature is very likely to keep increasing. Thus, it is time to do something to reduce the GHG emissions caused by transport. Driving electric cars could be a solution. Electric vehicles (EVs) may seem like something for future since people already get used to drive gasoline powered cars for so many years especially for my generation. However, it has been more than 100 years since the first known electric car being introduced. By looking at the history of electric vehicles, it is easy to conclude that the development of battery technology plays a major role in terms of the faith of electric vehicles. Currently, the most common battery used in electric vehicles is Lithium ion (Li-ion) batteries. However, researchers at the University of Surrey indicated that they believed that the supercapacitor is a new alternative to battery power, which allows electric cars to travel similar distances as gasolines cars for a single charge with an extremely short recharge time. Therefore, in this project, I am going to mainly focus on how supercapacitor could be used in EVs (Njolinjo, 2018).

Project Goal

As mentioned above, this project focus on the use of supercapacitor in EVs. Thus, it is essential to understand these two concepts (supercapacitor & EVs). The main body will start with the historical context of EVs and the current technology being used. It is also crucial to compare the performance between current battery technology and supercapacitor to determine if supercapacitor is a batter choice for EVs. Moreover, the technical difficulties of replacing battery with supercapacitors should also be analyzed. Last but not least, a financial analysis of using supercapacitor in electric vehicles is also important because it directly impact if it is feasible to replace current battery technology with supercapacitor. Overall, the goal of this project is to understand supercapacitor and to see how it could be used in EVs and whether it is worthwhile to use. 

Research Approach

History of EVs

Before getting into the main part, just to be clear that only Battery EVs will be analyzed in this project. Hybrid EVs and Fuel Cells EVs are not included.

Instead of using gasoline motors, EVs are those use electric motors. EVs may seem like something for future since people already get used to driving gasoline-powered cars for so many years, especially for my generation. However, it has been more than 100 years since the first known electric car being introduced. Different resources claim differently in terms of the one who created the very first EV. However, it is sure that EVs came up in early 1800s (Matulka, n.d.). By 1900, about one third of all vehicles on the road are electric vehicles. The market share of electric continued to expand for the next decade. Electric cars quickly became popular in urban areas because they were quiet, easy to drive and more importantly did not pollute the air by emitting smelly gas. However, all electric cars disappeared by 1935 for several reasons. First of all, the electric starter was introduced in 1908, which eliminates the need for the hand crank for gasoline powered cars. In addition, gas became cheap and available when the Texas crude oil being discovered. Moreover, the high cost of an electric car was almost two times more expensive than a gasoline car. Electric cars stayed in the dark ages for more than three decades due to the lack of technology improvement (Chan, 2007). The incredibly high gasoline price in the 1970s drove electric cars back into customers’ attention.  However, electric vehicles had limited performance due to the limit range it can go. Fast forward to 1990s, people started to have an environmental concern of gasoline cars, and that gave electric cars a chance to regain the market share. People suggested that the introduction of the Toyota Prius in 1997 was the turning point because the Prius was the first electric car that being mass-produced. For the following 10 years, Prius was the best-selling hybrid in the world (Matulka, n.d.). With the development of battery technology, the luxury electric car can go up to 300 miles on a single charge.  High gasoline price and environmental concern give the electric vehicles more possibility for the future. Nowadays, EVs play an important role in the car sharing system. Even though users need to travel for longer distances, EV is a good choice because the user can change to another fully charged EV at the midway service station with the help of better infrastructure (Chan, 2007). After having a basic understanding of the history, it is reasonable to state that the development of Internal Combustion Engines (ICEs) and battery technology directly affect the rise and fall of EVs. 

Comparison Between ICEs and EVs

By analyzing the history of EVs, it is obvious that the public was making decisions between these two types of vehicles. The dark time for EVs was the heyday for gasoline powered cars. In other words, the fall of EVs was partially because of the development of ICEs. According to Table 1, the market shares of EVs were continuing to increase in the past five years for the majority of the countries listed below. However, even though the overall trend was exciting, the actual market shares were still very tiny except for Norway. The ICEs are still dominated the market. Therefore, it is necessary to figure out why ICEs could take charge of the market for such a long time.

Table 1. Electric Cars Market Shares by Country, 2005-2016. Source: International Energy Agency

Advantages of ICEs– High Energy of Gasoline

Table 2. Energy Per gram

Source: Physics and Technology for Future Presidents by Richard A. Muller

As Table 2 shows, it is surprisingly to notice the significantly amount of energy per gram that gasoline contains compared to other resources, and that is why gasoline is so valuable and useful as fuel. Compared to auto battery per gram, gasoline contains 340 times more energy. Thus, the high energy that gasoline has is the fundamental physics reason why gasoline is so popular. Even though only 20% of the energy of gasoline converted to wheel energy and comparing the efficiency of battery (85%), gasoline is still roughly 80 times better than auto battery in terms of energy used (Muller, 2012). In other words, batteries are only 80 times worse than gasoline when both energy and efficiency are considered. This number is small enough for electric cars to be feasible but still large enough for battery-powered cars to compete.

Advantages of ICEs – Infrastructure & Technology

Infrastructure is one of the biggest advantages that ICEs have because gas stations and repair shops are almost everywhere. Moreover, due to the increasing demand, more and more infrastructure will be built. The infrastructure makes it convenient to own a gas car. Whenever there is a need to refuel, drivers do not need to look far to find the gas station. Within a few minutes, the gas car is ready to travel another 300 miles or more. However, it takes hours for EVs to recharge, and not to mention that most EVs usually travel a shorter distance compared with ICEs before its next recharge. It is true that people can charge anywhere when they have electricity. However, it is not good to recharge before it needed because charge whenever the electricity is available will cause the battery die sooner. Moreover, the average repairing time for EVs could be longer than ICEs due to the lack of repairing stores. Comparing with EVs, the technology of ICEs is more mature and easier for the public to understand and accept.

Advantage of ICEs – Lower Cost and Longer Travel Distance

The cost will be taken into consideration for the majority of people when considering purchase a vehicle.  According to Kelly Blue Book, the average new car price was $36,113 in 2017. It is worth to mention that that number took EVs into consideration. Considering EVs only made up less than 2% of the market, there was not a big problem by treating the average selling price for all cars as the selling price of gasoline cars. Even though the price is continuing to increase, the initial cost of buying a gasoline-powered car is still lower than buying an EV when the average price for EVs was just about $50,000. Keep that initial purchasing cost in mind and take a look at how far both ICEs and EVs can go before they need a refuel or recharge. According to Yurday (2018), EVs can travel 180 miles on average on a single charge. However, that number goes up to 400 miles when we talk about gasoline cars. People may ask themselves why they would spend more money on an EV that can only go 180 miles before they consider the difference between EVs and ICEs on operating and maintenance costs. It is worth to mention that the average cost to drive an EV in the United States is $485 every year, but that number climbs to $1117 for ICEs based on the report by Michael Sivak and Brandon Schoettle from The University of Michigan Sustainable Worldwide Transportation in 2018. However, the replacement cost of a battery was not considered when they calculated that number. Car batteries cannot last forever. According to Zart, the average price of a car battery pack is $209/kWh in 2017, and that number needs to decrease to $100/kWh in order to be comparable with normal gasoline powered cars (2017).

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By summarizing this section, the high energy that gasoline contains is the fundamental physic reason why ICEs dominated the market for such long time. Moreover, the developed infrastructure and mature technology is another important reason why ICEs make up almost 99% of the market. Last but not least, the lower cost of ICEs offers the customers the biggest reason to choose them instead of the EVs with higher cost and lower travel range. However, nothing can last forever. There is a possibility that EVs could become the leader of the industry for various reasons. For the next section, I would like to discuss the advantages of EVs.

Advantage of EVs – Decreasing Overall Cost

As mentioned above, one of the biggest reasons why ICEs dominated the market is gasoline powered cars cost much less at this point. However, it is undeniable that the cost for owing an EV is also decreasing with the development of the technology as shown in Figure 2. More importantly, based on the prediction, buying an electric vehicle is almost the same as purchasing a normal gasoline-powered car by mid-2020s.

Figure 2. Source: https://ilsr.org/report-electric-vehicles/

On the other hand, the price of gasoline is going up with the increasing demand and limited resources. When the gasoline is no longer cheap, the cost of operating a gas car will soar up. According to Figure 3, the overall trend of the gasoline price is increasing. Thus, it is not hard to predict that the cost of gasoline will keep increasing in the future. One day, the cost of driving a gasoline car and an EV would be almost the same. For those who are price sensitive, they may purchase an EV in the near future. Lastly, the compensation from the government is another advantage that the EV have in terms of cost.

Figure 3. Average Historical Annual Gasoline Pump Price, 1929-2015 Source: https://www.energy.gov/eere/vehicles/fact-915-march-7-2016-average-historical-annual-gasoline-pump-price-1929-2015

Currently, gasoline-powered cars filled the market because of the advantages that I mentioned above. However, gasoline-powered cars may lose its competitive advantages and markets with the development of battery technology and the decreasing overall cost of having an EV. 

The Development of Car Battery Technology

The most important part of an EV is its battery. The development of car battery technology directly affects the rise and fall of electric vehicles. In the late 1800s, electric car batteries were made up by many non-rechargeable cells in the first place. But it soon was replaced by rechargeable lead-acid cells (A Short History of Electric Car Batteries, 2017). As mentioned before, electric cars became the most popular cars on the road for being quiet, easy to operate and environmental-friendly.  For the following half century, there was not a big improvement on car batteries, and that was the main reason why electric cars disappeared for such a long time. In the 1970s, with the development of higher-density batteries (Nickel-Cadmium cells), electric cars returned to the public’s sight. However, it did not last long because cadmium is toxic. Furthermore, Nickel-Metal Hydride (NiMH) batteries were being introduced because of the even higher energy-dense and toxic free. However, NiMH was not helped a lot because it was too heavy to carry. At this moment, Lithium-ion and Lithium-Iron-Phosphate cells are the highest –density batteries (300% to 400% more density than LA batteries) and the most common batteries used in electric cars (A Short History of Electric Car Batteries, 2017). Based on the timeline of car batteries that mentioned above, it is clear that the fate of electric vehicles is closely related to the development of car batteries. Whenever there is an improvement on car batteries, electric vehicles got a chance to return to the market. However, only significant battery technology improvement could help electric vehicles to continue to grow in the market. The past 20 years has been the most significant period for electric vehicles since it first boom in the 1900s. EVs would not be able to reborn without the development of batteries technology. Now, it is the time to focus on current batteries technology.

Even though some recent research indicates that Li-Fe phosphate (LiFePO4) has a better performance under real-world driving conditions, Lithium-ion Battery is still the most common one to use today due to its high energy density, charge retention, and low maintenance (Global Electric Vehicle (EV) Battery Market by Battery Type, Vehicle Technology, Vehicle Type and Region (2014-2025): CAGR to Grow at Over 19% During 2018-2025., 2019) . More importantly, the production technology of LiB cells and packs has achieved a significant improvement in the last five years (Kwade et al., 2018). Creating a safe battery with high performance and low cost is always the goal for experts and technologists.  However, it is not easy due to the complexity of LiB batteries. It is not only because designing batteries consists a large number of consecutive process steps, but also the material selection and transforming the process from lab scale to massive production scale (Kwade et al., 2018). Other than that, battery lifetime and temperature range also need to be taken into consideration. Currently, depends on different auto brands and models, the lifetime of LiB batteries can last about 8 to 15 years, and adapt the temperature difference from -40C to 60C or even 80C. Moreover, it is not a problem for some luxury electric vehicles travel more than 300 miles on a single charge, and number various depends on models and brands (Bettencourt, 2017).  Of course, the cost is also various based on different characteristics and performance. There is a no doubt that the advancement of battery technology is the fundamental reason for electrical vehicles to gain more market shares.

SWOT Analysis of Lithium-ion Batteries (to be continued)

Source: Budde-Meiwes, H., Drillkens, J., Lunz, B., Muennix, J., Rothgang, S., Kowal, J., & Sauer, D. U. (2013). A review of current automotive battery technology and future prospects. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 227(5), 761–776. https://doi.org/10.1177/0954407013485567

SWOT Analysis of Supercapacitors (to be continued)

Source: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.486.7050&rep=rep1&type=pdf

More information: https://doi.org/10.1016/j.eap.2018.08.003  

Results / Analysis

Advantages and disadvantages of supercapacitors compared with Lithium – ion battery

Parameters can be compared:

-          Cost

-          Cycle lifetime

-          Energy density

-          Power density

-          Energy efficiency

More information can be found at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3945924/

https://onlinelibrary.wiley.com/doi/full/10.1002/advs.201600539

Financial Feasibility

Cost and ROI should be take into consideration when considering its feasibility of replacing battery with supercapacitor. More research needed

Interpretation and Conclusions

-          It should be clear at this point that if supercapacitor is a good alternative for EVs.

-          Environmental impacts should also be mentioned here

Bibliography

• Budde-Meiwes, H., Drillkens, J., Lunz, B., Muennix, J., Rothgang, S., Kowal, J., & Sauer, D. U. (2013). A review of current automotive battery technology and future prospects. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 227(5), 761–776. https://doi.org/10.1177/0954407013485567
• Chan, C. C. (2007). The state of the art of electric, hybrid, and fuel cell vehicles. Proceedings of the IEEE, 95(4), 704-718. doi:10.1109/JPROC.2007.892489
• Cole, S., Hertem, D. V., Meeus, L., & Bellman, R. (2005, December 18). SWOT analysis of utility-side energy storage technologies. Retrieved from http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.486.7050&rep=rep1&type=pdf
• Global Electric Vehicle (EV) Battery Market by Battery Type, Vehicle Technology, Vehicle Type and Region (2014-2025): CAGR to Grow at Over 19% During 2018-2025. (2019, February 26). M2 Presswire. Retrieved from http://link.galegroup.com.arktos.nyit.edu/apps/doc/A575923476/ITOF?u=nysl_li_nyinstc&sid=ITOF&xid=c8951d96
• Horn, M., MacLeod, J., Liu, M., Webb, J., & Motta, N. (2019). Supercapacitors: A new source of power for electric cars? Economic Analysis and Policy, 61, 93-103. doi:10.1016/j.eap.2018.08.003 
• Kwade, A., Haselrieder, W., Leithoff, R., Modlinger, A., Dietrich, F., & Droeder, K. (2018). Current status and challenges for automotive battery production technologies. Nature Energy, 3(4), 290-300. doi:10.1038/s41560-018-0130-3
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• Matulka, R. (n.d.). The History of the Electric Car. Retrieved March 26, 2019, from https://www.energy.gov/articles/history-electric-car
• Naoi, K., Naoi, W., Aoyagi, S., Miyamoto, J., & Kamino, T. (2013). New generation “nanohybrid supercapacitor”. Accounts of Chemical Research, 46(5), 1075.
• Njolinjo, D. (2018, February 26). Alternative to traditional batteries moves a step closer to reality after exciting progress in supercapacitor technology. Retrieved February 12, 2019, from https://www.surrey.ac.uk/news/alternative-traditional-batteries-moves-step-closer-reality-after-exciting-progress
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