By Jessica Shea Choksey

A fuel cell stack powers the redesigned 2021 Toyota Mirai, using compressed hydrogen fuel stored in carbon-fiber tanks underneath the car’s interior. (Toyota)

Expanding renewable energy and reducing the use of fossil fuels will produce cleaner air and a healthier environment while slowing global warming and climate change. As evident in Volvo’s electrification of its entire model range, the auto industry’s growing focus on electric vehicles (EVs) is one of the keys to achieving these goals.

Unlike gasoline- and diesel-powered vehicles, EVs provide transportation without directly releasing harmful greenhouse gases into the atmosphere. In addition to supplying zero-emissions travel, EVs also eliminate the costs associated with fueling and maintaining internal combustion engines (ICEs) while often delivering a more responsive and fun driving experience.

As the shift to EVs gains momentum, new electrification and alternative clean energy developments continually emerge. For example, fuel cell electric vehicles (FCEVs) operate much like standard battery electric vehicles (BEVs), using one or more electric motors to propel a vehicle. However, with an FCEV, the primary energy source for these electric motors is not a battery containing stored electricity. Instead, a hydrogen-powered fuel cell stack located within the vehicle creates the necessary electricity through an electrochemical reaction.

To generate electricity, a fuel cell combines oxygen from air drawn in from outside the vehicle with compressed hydrogen fuel stored in special tanks underneath the vehicle. The hydrogen flows into the fuel cell’s anode, while the oxygen flows into the cathode. An electrolyte membrane separates the anode and cathode.

The anode splits the hydrogen fuel’s atoms into protons and electrons. The electrons are forced through a circuit to generate an electric current that powers the vehicle, while the protons pass through the electrolyte membrane to the cathode. In the cathode, the protons and the spent electrons combine with the oxygen from the outside air, creating water and heat. These are the byproducts of the entire process, and they exit the vehicle from the exhaust outlet as steam.

Similar to a BEV, an FCEV operates without a direct carbon footprint. In fact, the water vapor it emits is cleaner than the air it takes in. However, the processes necessary to create the FCEV’s powertrain and the hydrogen it runs on are carbon-emitting, as is true of BEVs.

As 2020 comes to a close, steam methane reformation of natural gas produces most of the available hydrogen fuel. Electrolysis also extracts hydrogen using electricity derived from solar and wind sources, but this accounts for a small percentage of available hydrogen. Still, despite the carbon output created by hydrogen fuel production, an FCEV is a much cleaner and greener method of transportation than a gasoline- or diesel-fueled vehicle with an ICE.

To suit a variety of power requirements, fuel cell technology is scalable. Stacking individual fuel cells creates a more powerful propulsion system, and the taller the stack, the more electricity it potentially generates. Due to this stackability, fuel cells are versatile and can power various vehicle types, from subcompact cars to large commercial trucks.

FCEVs offer certain advantages over BEVs. First, while it can take hours to recharge a BEV, refueling with hydrogen can take only a matter of minutes, and the process is comparable to fueling up at a gas station. Second, in terms of range, FCEVs can travel further than BEVs due to their potentially higher energy output and lower weight.

Currently, the biggest drawback to FCEVs is the lack of a hydrogen refueling infrastructure. Due to low demand and high-cost issues, there are few hydrogen refueling stations in the U.S. Those that exist are in California and Honolulu, Hawaii. More are planned or under construction in California and the Northeast, but a robust hydrogen fueling network is still a long way off.

Nevertheless, vehicles like the redesigned 2021 Toyota Mirai demonstrate FCEVs’ viability for consumers, while companies such as Daimler and Volvo are partnering to develop the technology for commercial purposes. Some might view FCEVs as carrying too little impact too late in the game. Still, they play a potentially important role in the auto industry’s evolution from fossil fuel-based transportation to electrified solutions with zero emissions.