Separate chemistry 1 Revision Notes

How Fuel Cells Work

Fuel cells convert chemical energy into electrical energy through redox reactions. Hydrogen fuel is fed to the anode, where it loses electrons (oxidation) to form hydrogen ions. These electrons travel through an external circuit, generating electricity. Oxygen is fed to the cathode, where it gains electrons and reacts with the hydrogen ions that have passed through an electrolyte to form water. The only by-product is water, making them very clean at the point of use.

Strengths of Fuel Cells

Fuel cells have high efficiency in converting fuel to electricity, often exceeding internal combustion engines. They produce zero harmful emissions at the point of use (only water). They can operate continuously as long as fuel is supplied, unlike batteries that need recharging. They are quiet in operation and have fewer moving parts, which can lead to lower maintenance in some applications. Examples include powering vehicles, providing emergency backup power, and applications in space exploration.

Weaknesses of Fuel Cells

Key challenges include the high cost of production, particularly for catalysts like platinum. Hydrogen storage and transport are difficult and expensive, requiring high pressures or cryogenic temperatures. The infrastructure for hydrogen refuelling is currently limited. The production of hydrogen often relies on fossil fuels, leading to carbon emissions upstream, unless 'green' hydrogen (produced by electrolysis using renewable energy) is used. Fuel cells also have a limited lifespan and can be sensitive to impurities in the fuel.