Liquid Air Batteries: The Key To Energy Storage?
One of the obvious drawbacks of wind and solar energy is the simple fact that the wind doesn’t blow all day long and the sun doesn’t shine constantly (it does actually but things get in its way). A reality often referred to by the press as intermittency.
A problem exacerbated by the fact that wind turbines in particular tend to have an irritating habit of being at their most productive when demand for electricity is at its lowest (mornings and evenings apparently) and then getting lazy during the middle of the day when demand normally rises.
The obvious answer to this problem is energy storage, or batteries, to enable the power supply to be ‘leveled out’ during the course of the day (and night). But as anyone who has ever investigated buying an e-bike will know, batteries are expensive. And not always particularly sustainable in their current forms, as most types still require rare metals.
A problem which one particularly clever inventor, Peter Dearman from Hertfordshire in the UK, believes he may be able to address with his invention of a ‘frozen air’ energy storage system.
It works by taking energy from a renewable source such as a wind turbine during peak production times and using it to freeze air (after removing the water vapour and carbon dioxide) down to -310F, at which point it turns into a liquid and is held in a giant vacuum flask. Warming it up again later, back into a vapour, results in an increase in pressure which can be used to either drive an electricity-generating turbine, or, better still, to turn those idle wind turbine blades.
Dearman originally developed his ‘cryo power’ system to power cars and has, in his own words, “been working on it off and on (pun intended we hope) for close on 50 years”.
Dearman has been reported as saying that he feels his ‘liquid air’ technology can compete with other forms of energy storage because it doesn’t need any rare materials in its production.
More good news is that testing of Dearman’s technology is at a fairly advanced stage with trials having been carried out over the last 5 years at a power station in Slough, just outside London, run by Highview Power Storage. They are currently looking to apply Dearman’s technology on a larger scale so that it can be used on the main power grid.
Highview has calculated that the process is only currently about 25% efficient but that it has the potential when it is applied on a larger scale to reach 70% efficiency.
There are several ‘holy grails’ when it comes to renewable energy. Cheap, sustainable energy storage is definitely one of them. Big batteries. Without them, wastage is almost inevitable, like having to leave a tap running all day without a plug in the sink.
While power grids themselves are a type of battery, in that they are able to store energy for a certain amount of time and redistribute it as and when required, large scale ‘local’ storage such as that being developed by Dearman would certainly help level out those differences between peak demand and peak production. To extend the water analogy, they could act as small reservoirs dotted around the grid.
But, and it’s a biggish but, haven’t we heard all this before? Haven’t batteries been on the verge of a technological renaissance for ages now? Small battery technology may have moved on in the last 20 years – just look at what’s happened to mobile phones – but big batteries still seem to be waiting for their makeover.
Whether this turns out to be it, we shall have to wait and see.
(image courtesy of Highview Power Storage)
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