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| Public domain image by Pexels on Pixabay |
As
we wean ourselves off fossil fuels and move to renewables such as wind
and solar power, the issue of energy storage becomes more significant.
So when the Sun doesn't shine and the wind doesn't blow, we need a
reservoir or buffer of energy we can draw on to maintain the electricity
supply. Some technologies will need to be developed or are already at a
trial stage such as underground hydrogen or compressed air storage.
Both of these can be used to generate electricity. Hydrogen has the
advantage that it doesn't produce CO₂ when it burns, simply water or
H₂O. In a thermal power station (which have traditionally burned coal,
oil, gas or turf), burning hydrogen produces heat that boils water,
making steam which then drives turbines to spin alternators and generate
electricity. Other technologies are already in use such as pumped
storage (e.g. Turlough Hill), where water is pumped to a higher level
when there's a surplus of electricity and generates power on demand at a
later time as it flows downhill through the turbines to turn the
alternators. Another way of storing electricity is simply in large
lithium ion battery storage facilities, but that's controversial as we
saw locally because of the concern over battery failure and fire. The
technology as described in this article envisages storing heat in
graphite blocks at extremely high temperatures of up to 2,600 °C. Heat
is transported around the system using molten tin (a technique already
used in some nuclear power stations and submarines). This specific
system has a 41% efficiency, much lower than that of battery storage,
and because of the difficulty of insulating against heat loss, 1% of the
stored energy is lost per day. However as a short term means of storing
energy, it may be promising.