Is this the technology that makes 100 per cent energy from renewables the most practical solution?

By David Toke

Work is now underway on an energy storage scheme which could be the most significant energy breakthrough project in the last quarter of a century. It is the 50 MW liquid air storage plant in Manchester led by the company Highview. This (as yet small step) has a very good chance to pave the way for 100 per cent renewable energy systems in which sceptics who cite so-called intermittency from solar and wind as a barrier to providing total renewable energy supply are just blown away.

Yulong Ding is the founding Chamberlain Professor of Chemical Engineering at the University of Birmingham and his team has amassed some 70 patents covering various energy related technologies including storage. Cryogenic storage of air looks to me like it will be a total game-changer because of its ability to store, relatively cheaply and conveniently – renewable energy so that if there is no wind or sun then stored renewable energy can be fed back through a turbine to generate electricity.

Professor Ding told me: ‘With this technology you can store gigawatts and even terrawatt hours of renewable energy for weeks or months (which can also serve short and medium term needs), and  the leakage is, maybe a fraction of 1%. Nearly 60 per cent of the initial renewable electricity input can be recovered after storage. Recent developments of the system have shown that the technology can be used for combined heating, cooling and power, which can have an efficiency at least 70%’.

‘This technology clearly has the potential for the delivery of energy that comes 100 per cent from renewable energy sources’.

Highview Power supported his Royal Academy of Engineering Industrial Chair at Birmingham in the years 2014-19, so it gives Yulong great pleasure to see the first large scale commercial plant using the technology that was his brainchild come into being.

Highview’s 50 MW project, which is costing a total of £85 million to build, can  store 250MWh. This scheme is tied to a gas peaker plant so that its operations are more energy efficient, but operating in this niche gives the technology a good start, and a chance to optimise its systems. That having been said, the scheme is surprisingly cheap for the first of its kind.

Already I can see that a 100 per cent renewable energy system using multiple versions of this technology would, together with wind and solar power, be able to produce guaranteed all year round firm power much more cheaply than nuclear power or carbon capture and storage plant. Please note: that’s even before the technical optimisation that is bound to occur.

Of course there are other storage technologies which could compete with liquid air; storing renewable energy as ammonia, as hydrogen, or through using ‘flow’ batteries are all plausible options. But cryogenic air storage does have some serious advantages – it looks relatively low cost for a start, you don’t have to freeze it to as low a temerature as you would hydrogen for example – the storage substance (liquid air) is less difficult to handle compared to ammonia and hydrogen, and the technology seems now to be more developed than flow batteries. On top of this, compared to all of the other options, it seems to involve a higher conversion efficiency cycle of renewable energy back to energy after storage.

All of these systems would have in common the ability to make use of excess renewable energy as a storage fuel input, such excess production being available at very low cost.

Despite the fact that Professor Ding could now quite easily hang up his boots and bask in the glory of inventing this world shattering piece of technology, he continues to produce some devastatingly innovative research into energy storage technology. He says:

‘We are pursuing commercial application of composite phase change material (cPCM) based heat storage systems that can turn curtailed wind power for space heating. Our work has led to the world first large scale (6MWh / 36MWh) commercial cPCM demonstration plant in 2016. Since then some 20 plants have been built with a total storage capacity of 1.2GWh.’