Question

4-A. Can a fuel cell be both an electrollzer producing hydrogen and a power source producing electricity and heat?

B. Storage batteries have great potential for storing off-peak power as well as accommodating ‘green energy’ However they have serious problems limiting their use. What are they?

Answer 1

Ans to Q No. 4 A:

Fuel cell is a device which converts chemical energy from hydrogen-rich fuels into electrical power and usable high quality heat in an electrochemical process. It has two electrodes where the reactions take place and an electrolyte which carries the charged particles from one electrode to the other. For a fuel cell to work, it needs hydrogen (H2) and oxygen (O2). The hydrogen enters the fuel cell at the anode. A chemical reaction strips the hydrogen molecules of their electrons and the atoms become ionized to form H+. The electrons travel through wires to provide a current to do work. The oxygen enters at the cathode, usually from the air. The oxygen picks up the electrons that have completed their circuit. The oxygen then combines with the ionized hydrogen atoms (H+), and water (H2O) is formed as the waste product which exits the fuel cell.

The reactions involved in a fuel cell are as follows:

oxidation reaction at anode:

2H2 → 4H++ 4e-

Reduction reaction at cathode

O2 + 4H+ + 4e- → 2H2O

Net cell reaction:

2H2 + O2 → 2H2O

On the other hand, An electrolyzer is a piece of electrochemical apparatus designed to perform electrolysis i.e splitting a solution into the atoms from which it's made by passing electricity through it. In other words An electrolyzer is somewhat similar to battery working in reverse.

Hence a fuel cell can not be used both as an electrolizer producing hydrogen and a power source producing electricity and heat.

Ans to Q No 4 B:

Some of the problems associated with storage batteries are as follows:

1.   Lithium ion batteries have high “round-trip efficiency” but are very expensive, and a lithium metal-air battery, when it absorbs moisture from the air in addition to the oxygen it needs, can explode.

2.   Another Potential negative impacts of electricity storage is environmental pollution. For example, batteries use raw materials such as lithium and lead, and they can present environmental hazards if they are not disposed of or recycled properly. Lead-acid batteries contain sulfuric acid and large amounts of lead. The acid is extremely corrosive and is also a good carrier for soluble lead and lead particulate. Lead is a highly toxic metal that produces a range of adverse health effects particularly in young children.Exposure to excessive levels of lead can cause damage to brain and kidney, impair hearing; and lead to numerous other associated problems.

3.   Storage batteries can also generate a lot of solid waste.