Fuel cells cleanly and efficiently convert chemical energy from hydrogen-rich fuels into electrical power and heat through an electrochemical process. Each individual fuel cell contains an anode, cathode, and electrolyte layer. When hydrogen enters the fuel cell, it reacts with oxygen to produce electricity, heat, and water, while emitting virtually no pollutants. Fuel cells continuously generate electricity as long as fuel is supplied.

1. Fuel cells
Unit 5

2. Fuel cell concept:
• A fuel cell electrochemically combines
hydrogen and oxygen to produce electricity,
heat and water in a highly efficient process
that avoids the emission of pollutants.

5. Fuel cell
• Fuel cells cleanly and efficiently convert chemical energy from
hydrogen-rich fuels into electrical power and usable high
quality heat in an electrochemical process that is virtually
absent of pollutants.
• Similar to a battery, a fuel cell is comprised of many individual
cells that are grouped together to form a fuel cell stack. Each
individual cell contains an anode, a cathodeand
an electrolyte layer. When a hydrogen-rich fuel such as clean
natural gas or renewable biogas enters the fuel cell stack, it
reacts electrochemically with oxygen (i.e. ambient air) to
produce electric current, heat and water. While a typical
battery has a fixed supply of energy, fuel cells continuously
generate electricity as long as fuel is supplied.

6. Working:
• As illustrated in the diagram , fuel is supplied to the
fuel cell stack where methane (CH4) from the fuel is
internally reformed to create hydrogen (H2) and
carbon dioxide (CO2).
• Spent fuel exits the anode and is consumed to supply
oxygen (O2) and CO2to the cathode. Heat and water
vapor (H2O) exit the cathode.
• The resulting electrochemical reactions in the fuel cell
anode and cathode produce direct current (DC) power,
which is then converted to alternating current (AC)
power by the electrical balance of plant.
• The cathode exhaust supplies heat to warm the
incoming fuel and externally to the customer for facility
heating and cooling or for making steam.

7. Advantage of fuel cell:
• Because there is no combusting of fuel,
virtually no harmful emissions are generated
by the fuel cells. This results in power
production that is almost entirely absent of
nitrogen oxide (NOx), sulfur dioxide (SOx) or
particulate matter (PM).