Energy Storage

Why is energy storage important?

We don’t use energy at the same rate every hour of the day. We tend to use much less at night while we are sleeping and there are often surges through the day, for example when everyone turns the kettle on during a television advert break. It is therefore important to be able to adjust the power we produce according to what the demand is to prevent wastage or not reaching demand. Alternatively, if we could store the energy efficiently we would not have to worry about wasting any.

How do we store energy?

We can store energy in these different forms:

Chemically – a substance that can go through a chemical reaction has chemical energy, therefore chemical energy is stored in chemicals like hydrogen and fuels; as starch and glycogen in the body and in chemcials ready to produce electricity in batteries and fuel cells.
Electrically – using capacitors
Mechanically – Energy is stored through moving something with the initial energy into a position where it has potential energy. When released, the energy is released again as another type of energy. e.g. flywheels, springs, compressed air.
Thermally – using ice, hot bricks or molten salts.

What is the national grid?

It is a nationwide electricity transmission network where electricity can be carried from its source, e.g. a power station, to where we want to use it. There is very little capacity for storing excess electricity on it so controllers have to be careful to provide enough electricity when there will be a high demand for it, and try and limit how much is wasted when there is a low demand. With fossil fuels, it is relatively easy to change how much electricity is made according to demand, but with renewables it is not.

How do we store electricity?

Electrical energy is one of the highly sought after forms of energy but in order to store it, we often convert it to another type of energy. Here are some examples:

  • Batteries - stored as chemical energy. Sometimes these batteries run electric vehicles.
  • Compressed air - stored as potential energy.
  • Flywheels – stored as kinetic energy.
  • Hydrogen – stored as chemical energy.
  • Water reservoirs – stored as gravitational potential energy.

Importance

Our ability to use energy storage is becoming more important as renewable energy becomes more important. Many renewable energy systems rely on nature and the environment around them in order for them to be able to produce electricity. After all, that is why they are renewable! However, the sun, wind, tides, etc although useful are not always able to produce electricity whenever we want it. We have to instead collect the energy they produce when it happens. So, being able to store the energy in some form so that we can still power high demand periods of the day, whatever the weather or time of day is really important.

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