Hydrogen Fuel Cell Essay

Submitted By hanthaiuyen
Words: 656
Pages: 3

Electricity is a very convenient form of energy which is being used in most of necessary devices supporting modern life. About three – quarters of electricity generated in the UK comes from power stations fueled by fossil fuels such as coal, oil and natural gas. Normally electricity is converted through a two step process. Fuels are burnt converting chemical energy to heat. The heat is then transformed into electricity by generating steam to turn turbines. This is a highly inefficient method which requires a development of another more efficient method of producing electricity. In addition, fossil fuels are non – renewable energy resources. They are limited and will eventually run out. Fossil fuel cells produce carbon dioxide when they burn, which contributes to greenhouse effect and increase global warming. Coal and oil release sulfur dioxide when they burn, which causes breathing problems to living creatures and adds to acid rains. In the need of a new method of producing electricity, fuel cells are being developed. A fuel cell is a device that convert chemical energy directly into electricity through a chemical reaction which is a much more effective conversion. There are different types of fuel cells, but they all consist of an anode (negative side), a cathode (positive side) and an electrolyte to complete the circuit, allowing negative charges to move between the two sides of the fuel cells.

In a hydrogen-oxygen fuel cell, the anode is made of porous carbon with catalyst Pd or Pt and the cathode is also made of porous carbon containing the catalyst Pt. Between then is an electrolyte made of aqueous hydroxide (KOH or NaOH). Hydrogen gas is oxidized by oxygen gas in a controlled manner. Electrons are drawn from the anode to the cathode producing direct current electricity. Individual fuel cells produce a relatively small electrical potential of 0.7 Volts (theoretically 1.23 V), so cells are placed in series to increase voltage and meet an application’s requirement.

Balanced equation: 2 H2 + O2 → 2 H2O

There are many advantages of hydrogen fuel cells. In addition to electricity, fuel cells also produce water, heat and very small amount of other emissions. The energy efficiency of a fuel cell is about 40 – 60 %, or can be up to 85% if waste heat is captured in cogeneration situation such as combine heat and power for residential use. Low temperature fuel cells have low heat transmission which makes them ideal for military application. A high power density allows fuel cells to be relatively compact source of electric power, beneficial in application with space