## Fuel Cells

Fuel cells are cells in which there is a continual supply of reactants and thus creates a continual amount of energy. This energy is made via spontaneous redox reactions just like galvanic cells.

Oxygen is always a reactant at the cathode for all fuel cell reactions; oxygen is always being reduced. The type of reductant used determines what type of fuel cell it is. For example, the use of OH- or methanol as reactants are for alkaline fuel cells and methanol fuel cells respectively. A simple fuel cell which uses oxygen and hydrogen as its reactants is shown below.

$H_{ 2 }(g)+2OH^{ - }(aq)\rightarrow2H_{2}O(l)+2e^{-}$ $O_{2}(g)+H_{2}O(l)+4e^{-}\rightarrow 4OH^{-}(aq)$

Overall equation: $2H_{2}(g)+O_{2}(g)\rightarrow 2H_{2}O(l)$

Products of fuel cell reactions always lead to the production of water and electrical energy

• It is a one step process in converting chemical energy directly to electrical energy.
• No greenhouse gases are produced as a result of fuel cells.
• Uses a variety of fuels.
• Unlike batteries, do not need to be recharged.
• Electricity can be generated on-site.

• Requires constant fuel supply.
• Expensive; manufactured in limited numbers as fuel cells are a relatively new technology.
• Inverter is required to change direct current (DC) produced by the fuel cell to alternating current (AC) to use with electrical appliances used at home.
• Transport is limited and hydrogen storage and distribution is dangerous.