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…