Hydrogen Fuel Cell Vehicles: How They Work and Are Rated

A hydrogen fuel cell vehicle (FCV or FCEV) is an electric vehicle that makes its own electricity on board: hydrogen from a tank and oxygen from the air react in a fuel cell, and the electricity drives an electric motor. The only tailpipe emissions are water vapor and warm air. EPA rates these vehicles in MPGe and in kilograms of hydrogen per 100 miles, and, because fueling stations are scarce, availability matters as much as the rating.

Key takeaways

• A fuel cell vehicle is driven by an electric motor, like a battery-electric car, but its electricity comes from hydrogen rather than from a plug.
• fueleconomy.gov’s fuel cell vehicle ratings list MPGe and kilograms of hydrogen per 100 miles.
• The energy in about 1 kilogram of hydrogen is about the same as in 1 gallon of gasoline, according to the AFDC.
• Public hydrogen stations are limited and concentrated in California; check the AFDC station locator for your area.
• This site does not show a dollar fuel cost for hydrogen vehicles.

How a fuel cell vehicle works

fueleconomy.gov describes the type used in cars as a polymer electrolyte membrane (PEM) fuel cell. At the anode, a platinum catalyst splits hydrogen into protons and electrons. The membrane lets only the protons through to the cathode, so the electrons must travel through an external circuit, which creates the electrical current that powers the motor. At the cathode the electrons and protons combine with oxygen to form water, which flows out of the cell. Individual cells produce too little power, so many are assembled into a fuel cell stack.

The AFDC says a fuel cell coupled with an electric motor is two to three times more efficient than an internal combustion engine running on gasoline. It also notes that hydrogen can be burned in internal combustion engines, which is a different technology that produces nitrogen oxides, whereas fuel cell vehicles produce no emissions at the tailpipe other than water vapor and warm air.

How they are rated

The EPA label for an FCV shows fuel economy in miles per gallon of gasoline-equivalent (MPGe), the same unit used for electric vehicles; see what is MPG and MPGe. For hydrogen, a gallon-equivalent is the mass of hydrogen that has the energy of a gallon of gasoline. The AFDC states that the energy in 2.2 pounds (1 kilogram) of hydrogen gas is about the same as the energy in 1 gallon (6.2 pounds, 2.8 kilograms) of gasoline. fueleconomy.gov’s FCV listings give a combined MPGe and the kilograms of hydrogen used per 100 miles, which is the hydrogen counterpart of kWh per 100 miles (guide). Lower kilograms per 100 miles means more efficient.

Range is a separate label figure. fueleconomy.gov says some FCVs have achieved ranges comparable to conventional vehicles, about 300 to 400 miles, and that hydrogen contains much less energy per volume than gasoline or diesel.

Fueling

According to the AFDC, current light-duty FCVs store hydrogen in tanks at 10,000 pounds per square inch (marketed as H70) and can refuel in 3 to 5 minutes. For comparison, fueleconomy.gov gives a fast charge to 80% of an EV battery as taking about 30 minutes. The practical limit is where you can do it: fueleconomy.gov says hydrogen is available at a limited number of public stations, mostly in California, and the AFDC’s station locator is the place to check current availability. The AFDC says vehicles are available to consumers only in regions with existing hydrogen infrastructure.

Why this site shows no dollar cost

For gasoline, diesel and electricity, Gallonly uses dated EIA price series to estimate an annual cost, as described in how annual fuel cost is calculated. Hydrogen is not part of that set, so we show the EPA’s efficiency numbers and no cost. If you know the price of hydrogen at your station, you can multiply it by the kilograms used per 100 miles and your annual mileage.

Benefits and challenges, as the agencies state them

fueleconomy.gov lists these for FCVs powered by pure hydrogen: no harmful pollutants emitted, and hydrogen can be derived from domestic sources such as natural gas, coal, water, biogas and agricultural waste. It also lists challenges: vehicle cost, limited refueling infrastructure, durability of fuel cell stacks and consumer acceptance. The way hydrogen is produced affects the emissions upstream of the vehicle; fueleconomy.gov notes that some production methods cause emissions, typically much less than those associated with gasoline vehicles.

How it compares with other electric options

An FCV and a battery-electric vehicle both use an electric motor. The battery-electric option charges from the grid (EV range explained); the FCV refuels with hydrogen. Plug-in hybrids and conventional hybrids combine an engine with a battery; see hybrid vs plug-in hybrid vs EV. For FCV ratings, browse the car database.