Comparing Fuel Cell with Lithium-ion Battery Powered Electric Vehicles

Background

An average western person consumes 195kWh per day, from which 40kWh are due to car use and another 12kWh belongs to the transportation of goods we consume [1]. Since the beginning of 2000s car manufacturers, especially Toyota with its Prius, have been trying to reduce the CO2 impact of cars on the environment with the introduction of hybrid vehicles. Nowadays, as technologies have improved, we had the introductions of two types of full electric cars: fuel-cell powered electric vehicles (FCEVs) and lithium-ion battery powered electric vehicles (BEVs). This paper includes a description and comparison of both technologies, listing their advantages and drawbacks, whilst trying to adopt a global perspective.

Comparing Technologies

FCEVs are powered by the most abundant resource in the universe, which is hydrogen. In simple words, fuel-cells combine hydrogen, which is pressurized and stored in a tank, with oxygen and produce an electrical current and water. As it is already known, batteries allow us to store energy that was produced in power plants with the help of another type of chemical reaction. In both cases, electrical energy is converted into mechanical motion with the help of electromagnets. Both technologies considerably help reduce the CO2 emissions as long as the energy used to produce hydrogen or to charge the batteries come from clean energy sources.

When comparing both technologies, the first difference that can be mentioned is that unlike BEVs, FCEVs’ main attraction is that they don’t require long charging hours and can be refueled in 5 mins (same way as we do for petrol vehicles). Tesla Model 3 takes 8 hours to go from empty to full with a conventional Wallbox home charger, and around 30mins to go from 10% to 80% with the 120kW Tesla Supercharger [2] . With one full charge, both vehicles can have an autonomy of approximately 400 kms.

A Tesla Model 3 with a 75kWh battery cost between 10-12 dollars (in the United States) to charge from empty [3]. With a rated range of 500kms we get a final price of 2 – 2.4 cents per km. On the other hand, the price to currently fill a tank of 5kg hydrogen tank is 85 dollars that will give a range of 480kms and an average price of 17.7 cents per km. The price of a gal of gasoline is around $4/gal, but gasoline allows running half the distance than with a kg of hydrogen, resulting in an average price of 10 cents per km assuming a typical 25 miles per gallon efficiency.

Vehicle weight is another important difference between BEVs and FCEVs [4]. As shown in the figure below, the extra weight to increase the range of the fuel cell EV is negligible, while the battery EV weight escalates dramatically for ranges greater than 100 to 150 miles due to weight compounding. Each extra kg of battery weight to increase range requires extra structural weight, heavier brakes, a larger traction motor, and in turn more batteries to carry around this extra mass, etc…

Image from: https://www.energy.gov/sites/prod/files/2014/03/f9/thomas_fcev_vs_battery_evs.pdf

Points to Improve

One of the main issues BEVs have and will face is that our current electrical grid is not prepared to handle the loads generated by charging a BEV if everybody owned one instead of a gasoline vehicle. This will require large investments to upgrade our grid or a very educated demand response by consumers. Another topic which is not commonly mentioned when talking about BEVs is the environmental cost of Lithium mining and extraction. [5] It's extracted from salt, in Chile, but at a cost of using huge amounts of water. "In Chile’s Salar de Atacama, mining activities consumed 65% of the region’s water" found a Wired investigation. Lithium extraction also carries chemical hazards risks. "The extraction of lithium has significant environmental and social impacts, especially due to water pollution and depletion" NGO Friends of Earth stated in 2013.

It is also important to keep in mind that by implementing a transportation based in Lithium-Ion battery powered vehicles, we are just substituting our fossil fuels dependency for a reliance in another natural resource that is also finite, has very high environmental extraction costs, and that will just create a new monopoly for Lithium mines owners (as we have seen with petrol).

On the other hand, FCEVs biggest setback is that hydrogen is not readily available as an energy usage followed by the fact that there is an almost nonexistent transportation and distribution network for it. Right now, the most common way to industrially produce hydrogen is with Steam-Methane Reforming Reaction. An interesting alternative is producing hydrogen through water electrolysis. This could be a very efficient method because it will allow us to save the surplus energy produced by renewable technologies. As you may know, renewable technologies power production is often curtailed from grid because at peak production moments they tend to increase the grid’s voltage or frequency, resulting in wasted energy. Instead of curtailing or dumping this energy, it can be used to produce hydrogen for vehicles (energy storage).

Prospective owners face other drawbacks [6]. For one thing, fuel-cells do not take kindly to extreme conditions, especially temperatures below the freezing point of water. For another, they are not that durable. While internal-combustion engines can provide anything up to 10,000 hours of service, the best fuel-cells around today are good for little more than 4,000 hours.

Where Technologies Stand Today

Both technologies have big challenges to face. Particularly sponsored by Tesla, BEVs and Lithium-Ion seem to have a considerable advantage against FCEVs. [7] Tesla co-founder and CEO Elon Musk has dismissed hydrogen fuel cells as “mind-bogglingly stupid”. Nevertheless, it is important to mention that Japanese government and the country’s most relevant car manufacturers have a strong bet on fuel cells. [8] At least 11 Japanese companies, including JXTG Nippon Oil & Energy and Toyota Motor Corp, set up a joint venture to accelerate the construction of fuel stations for hydrogen fuel cell vehicles (FCEVs) in the country. Other companies involved in the venture include Nissan Motor, Honda Motor, Idemitsu Kosan, Iwatani Corp, Tokyo Gas, Toho Gas, Air Liquide Japan Ltd, Toyota Tsusho and Development Bank of Japan.

When it comes to the most relevant American car manufacturers [7]:

• GM has not released a fuel cell vehicle for the consumer market, but it has a joint venture with Honda to produce fuel cell stacks at a Michigan plant
• Ford has experimented with fuel cell variants of its Focus and Fusion cars, as well as the Edge crossover, but does not offer any such vehicles for sale.
• Fiat Chrysler does not have a fuel cell vehicle on sale in the U.S., but for 15 years it has supported research led by Professor David Antonelli, the chair of physical chemistry at Lancaster University in the U.K., that could bring costs down for the technology.

Certainly, both technologies are experiencing resource investments that will boost both technologies’ improvement, which will later be translated into cost reductions, higher efficiencies, and hopefully a significant decrease of environmental impact (at least for BEVs).

References

[1] D. J. MacKay, Sustainable Energy - Without the Hot Air, Cambridge: UIT Cambridge Ltd, 2009.

[2] R. Ingram, "Tesla charging stations: complete guide to the Tesla Supercharger network," Driving Electric, 20 03 2020. [Online]. Available: https://www.drivingelectric.com/tesla/52/tesla-charging-stations-complete-guide-tesla-supercharger-network. [Accessed 14 04 2020].

[3] Real Engineering, "The Truth about Hydrogen," 2018. [Online]. Available: https://www.youtube.com/watch?v=f7MzFfuNOtY&list=PLqelE-B9VXeJf_WU7n_0MMttfj86ulzqO&index=3&t=0s. [Accessed January 2020].

[4] C. P. Thomas, "Fuel Cell and Battery Electric Vehicles Compared," [Online]. Available: https://www.energy.gov/sites/prod/files/2014/03/f9/thomas_fcev_vs_battery_evs.pdf. [Accessed January 2020].

[5] R. Careceda, "Do lithium-ion batteries really deserve a Nobel Prize as a foundation of a fuel-free society?," 2019. [Online]. Available: https://www.euronews.com/2019/10/10/do-lithium-ion-batteries-really-deserve-a-nobel-prize-as-a-foundation-of-a-fuel-free-socie. [Accessed January 2020].

[6] The Economist, "Electric vehicles powered by fuel-cells get a second look," 2017. [Online]. Available: https://www.economist.com/science-and-technology/2017/09/25/electric-vehicles-powered-by-fuel-cells-get-a-second-look. [Accessed January 2020].

[7] J. D'Allegro, "Elon Musk says the tech is ‘mind-bogglingly stupid,’ but hydrogen cars may yet threaten Tesla," 2019. [Online]. Available: https://www.cnbc.com/2019/02/21/musk-calls-hydrogen-fuel-cells-stupid-but-tech-may-threaten-tesla.html. [Accessed January 2020].

[8] Reuters, "Japanese venture aims to build 80 hydrogen stations by March 2022," 2018. [Online]. Available: https://www.reuters.com/article/japan-hydrogen/japanese-venture-aims-to-build-80-hydrogen-stations-by-march-2022-idUSL4N1QN1F7. [Accessed January 2020].