Renewable energy sources are becoming increasingly popular. However, such energy can be wasted if an excess is available when it’s not yet needed. A particularly relevant example is solar power; solar panels provide most of their output during the day, while often a household’s greatest energy use is at night.
One way to get around this problem is by storing excess energy so that it can be used later. The most common way this is done is with large batteries, however, it’s not the only game in town. Phase change materials are proving to be a useful tool to store excess energy and recover it later – storing energy not as electricity, but as heat. Let’s take a look at how the technology works, and some of its most useful applications.
It’s All About Heat
The heating curve of water. Note the flat lines on the curve where the latent heat must be overcome to change phase.
Unlike batteries or capacitors, phase change materials don’t store energy as electricity, but heat. This is done by using the unique physical properties of phase changes – in the case of a material transitioning between solid and liquid phases, or liquid and gas. When heat energy is applied to a material, such as water, the temperature increases. However, when the liquid water reaches temperatures close to boiling point, something strange happens.
As more energy is put in, the temperature begins to flatline. This is because enough energy must be put in to overcome what is called the latent heat of vaporization – the energy required to turn the liquid into a gas. Eventually, once enough heat is put in, the water turns to ..
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