What are Fuel Cell Vehicles?
Instead of relying on oil and gasoline for fuel, fuel cell vehicles use hydrogen gas and oxygen from the air to produce electricity through an electrochemical reaction in a fuel cell. This electricity powers an electric motor that runs the vehicle. The only emissions from a hydrogen fuel cell vehicle are water and heat.

How Fuel Cells Work
A fuel cell consists of two electrodes - an anode and a cathode - separated by an electrolyte. Hydrogen gas is introduced to the anode where a catalyst splits the hydrogen atoms into protons and electrons. The protons are able to pass through the electrolyte to the cathode, but the electrons are forced to travel an external circuit and power an electric motor. At the cathode, oxygen gas is introduced. The protons, electrons and oxygen combine to form water and heat. The water is expelled from the fuel cell as exhaust. As long as hydrogen and oxygen are supplied, the fuel cell will continuously produce electricity as a byproduct of this electrochemical reaction.

On-Board Hydrogen Storage
For vehicles, hydrogen gas is compressed or liquefied and stored in high-pressure tanks on the vehicle. Compressed hydrogen gas is stored at pressures up to 10,000 psi, while liquid hydrogen requires cryogenic tanks to keep it chilled at -253°C. Whether stored as a compressed gas or cryogenic liquid, the hydrogen can then be supplied directly to the fuel cell stack to produce electricity. Automakers are also investigating new materials that can store greater amounts of hydrogen without high pressure or extreme cooling.

Comparison to Battery Electric Vehicles
While battery electric vehicles (BEVs) use charged batteries to directly power electric motors, fuel cell electric vehicles (FCEVs) use charged hydrogen tanks to indirectly power motors through the electrochemical reaction. This allows FCEVs to refuel much faster than charging large battery packs, with refueling times similar to gas vehicles. FCEVs also have a longer range per refuel than current BEVs. However, BEVs have a simpler design without the need for onboard hydrogen storage and a fuel cell.

Infrastructure Requirements
A major hurdle for widespread adoption of FCEVs is developing the necessary hydrogen refueling infrastructure. Currently there are very few publicly accessible hydrogen stations compared to the dense network of gas stations. Automakers are partnering with energy companies to establish initial hydrogen corridors between major cities. Meanwhile, home refueling using small hydrogen generators is being explored to further aid consumer adoption until public hydrogen infrastructure catches up. Safety standards also need to be established for handling and storing compressed or cryogenic hydrogen fuel.

Advantages of Hydrogen Fuel Cell Vehicles
Compared to traditional combustion engines or batteries, fuel cells have advantages that make them promising for powering vehicles:

- Emits Only Water - FCEVs produce no pollutants or greenhouse gases from the vehicle, only water vapor from the tailpipe. This makes them very eco-friendly.

- Quick Refueling - Unlike electric vehicles that require hours to charge, hydrogen tanks can be refilled in just a few minutes, similar to gas vehicles.

- Long Range - Current fuel cell vehicles can travel over 300 miles on a single tank, eliminating "range anxiety" associated with short-range batteries.

- Powerful Acceleration - The electric motors powered by fuel cells provide quick acceleration and torquey performance comparable to combustion engines.

- Silent Driving - Fuel cell vehicles are very quiet to drive thanks to the lack of an internal combustion engine.

Challenges for Mass Adoption
While fuel cells hold great potential, wider adoption faces challenges related to cost, durability and infrastructure:

- High Material Costs - Platinum catalysts used in fuel cells are expensive, adding to vehicle costs compared to gas or electric vehicles.

- Lifespan Concerns - Current fuel cells have limited lifespans of around 5,000 hours that exceed a vehicle's useful life. Improving durability is crucial.

- Scarce Infrastructure - Developing a hydrogen fueling network comparable to gas stations will require major investments by government and industry.

- Public Perception - Consumers are unfamiliar with fuel cells and hydrogen compared to familiar BEVs and combustion engines. Education is needed.

The Future Looks Bright
Despite challenges, automakers remain committed to developing affordable, long-range FCEVs. As material and production costs decrease with innovations and scaling, fuel cell vehicles may become increasingly viable for consumers. Partnerships to deploy hydrogen stations aim to alleviate range and refueling anxieties. With their eco-friendly emissions and benefits of fast refueling over recharging, hydrogen fuel cell vehicles show promise as a leading sustainable transportation technology of the future.