Solar Energy Storage (Batteries vs Fuel Cells)

  • What is an efficient way to store solar energy?
  • By rechargeable batteries or in the form of hydrogen gas?
  • Which is more economical?

Recommended Items:

  • Light bulb
  • Solar cells
  • 2 Erlenmeyer flasks w/rubber stoppers and gas tubing
  • Syringe
  • Electrolyzer/ fuel cell
  • Assorted batteries
  • Voltmeter

Concepts used:

  • Chemistry, Solar cells, Fuel cells

Background:

Batteries use electrochemical reactions to produce electricity. In rechargeable batteries the negative and positive electrodes of an electrochemical cell can be replenished by reversing the reaction when an external electrical charge is applied. Fuel cells are like batteries in that they also consist of two electrodes sandwiched around an electrolyte. Unlike batteries, however, fuel cells do not run down or require recharging. Fuel cells will produce energy in the form of electricity and heat as long as fuel is supplied. A fuel cell converts the chemicals hydrogen and oxygen into water, and in the process it produces electricity.

In a fuel cell, hydrogen fuel is fed to one of the electrodes of the fuel cell while oxygen (or air) enters the fuel cell through the other electrode. Encouraged by the electrolyte catalyst, the hydrogen atom splits into a proton and an electron, which take different paths through the cell. The proton passes through the electrolyte. The electrons are carried through an external circuit creating a current that can be utilized before they return to the cathode, to be reunited with the hydrogen and oxygen in a molecule of water. A fuel cell system which includes a “fuel reformer” can utilize the hydrogen from any hydrocarbon fuel – from natural gas to methanol, and even gasoline. Since the fuel cell relies on chemistry and not combustion, emissions from this type of a system would still be much smaller than emissions from the cleanest fuel combustion processes.