How do hydrogen fuel cells compare to electric batteries?

In one line

The rule

Hydrogen fuel cells generate electricity by combining hydrogen and oxygen in a redox (reduction-oxidation) reaction, producing water and heat as byproducts. Electric batteries store electrical energy chemically and release it by allowing a chemical reaction to occur inside the battery.

• Hydrogen fuel cell reaction: 2H₂ + O₂ → 2H₂O + electrical energy
• Battery (general): chemical energy ↔ electrical energy (by redox reactions inside the battery)

Let's understand it simply

Imagine you want to run a fan during a power cut. You have two choices:

• Use a battery (like the one in your inverter or your phone)
• Use a hydrogen fuel cell

A battery is like a water tank. You fill it with water (charge it), and when you open the tap, water flows out (electricity comes out). Once the tank is empty, you must refill it (recharge the battery).

A hydrogen fuel cell is like a kitchen gas stove. You keep feeding it LPG (hydrogen gas here), and as long as you supply gas and oxygen (from air), it keeps burning and giving you heat (electricity here). You don’t need to recharge it; you just refill the fuel.

How it works

Hydrogen Fuel Cell

1. Hydrogen gas enters the anode side.
2. At the anode, hydrogen splits into protons (H⁺) and electrons (e⁻).
3. Electrons flow through an external circuit, creating electricity.
4. Protons move through the electrolyte to the cathode.
5. At the cathode, oxygen from air combines with the protons and electrons to form water.

Electric Battery

1. The battery has two electrodes: anode and cathode.
2. Inside, a chemical reaction releases electrons at the anode.
3. Electrons flow through a wire (external circuit) to the cathode, giving electricity.
4. The battery's chemicals are used up as it discharges.
5. To use it again, you must recharge (reverse the chemical reaction using electricity).

The story behind it

Batteries have been around since the early 1800s. Alessandro Volta made the first battery (Voltaic pile) in 1800, trying to create a steady source of electricity for experiments.

Hydrogen fuel cells were first shown by Sir William Grove in 1839. He wanted to turn hydrogen and oxygen into electricity directly, without burning them. Fuel cells became important for NASA in the 1960s to power spacecraft, as they also provide clean water for astronauts.

Where you see it in real life

• Electric cars (like Tata Nexon EV): Use large batteries to run the motor. You plug them in to charge.
• Hydrogen fuel cell buses (in some Indian cities): Use hydrogen tanks and fuel cells to run quietly and emit only water.
• Mobile phones and laptops: Use lithium-ion batteries for portable power.
• Remote villages: Solar panels charge batteries to provide light at night.
• Spacecraft (like Apollo missions): Used hydrogen fuel cells for electricity and water.
• Backup power for hospitals: Large batteries or fuel cells keep equipment running during power cuts.

Why it matters

• Clean energy: Both can reduce pollution if powered by renewable sources.
• Transport: Deciding between batteries and fuel cells affects the future of cars, buses, and trains.
• Energy storage: Batteries store solar/wind energy for use at night or during rain.
• Long journeys: Fuel cells can be refueled quickly, good for trucks and buses.
• Exams and jobs: Questions on this come in boards, NEET, JEE, and interviews for engineers.

Worked example

Let's compare refueling/recharging times and range for a car:

Given: Electric car battery range = 300 km, charging time = 6 hours
       Hydrogen fuel cell car range = 500 km, refueling time = 5 minutes
Step 1: Electric car charges slowly, range is less
Step 2: Fuel cell car refuels quickly, range is more
Step 3: For long trips, fuel cells are more convenient

Common mistakes

• Thinking both are the same: Batteries store electricity; fuel cells make it from fuel.
• Believing fuel cells pollute: They only make water if pure hydrogen is used.
• Assuming batteries are always greener: If electricity comes from coal, batteries can pollute too.
• Ignoring infrastructure: Hydrogen stations are rare; charging points for batteries are increasing.

Remember it

Batteries store and give out electricity directly; fuel cells make electricity from hydrogen and oxygen, giving only water as waste.