Liquid Air

“Thinking Outside The Wires.”

Billions of litres of liquefied air (liquid oxygen, liquid nitrogen) are used each year in a variety of industrial applications throughout the world; and their production is a multi-billion dollar global industry. But their value in clean energy is only just emerging.

Air is in fact the most natural, abundant and environmentally friendly energy storage medium of all.

The process is simple:

  1. At -196C, air becomes a liquid. One litre of liquid air is “manufactured” by compressing and cooling 710 litres of air. Liquefying air uses energy, i.e. ‘stores’ it.
  2. Storing the liquid air is straightforward as it can be held in a non-pressurised insulated tank; it is not flammable (it is in fact classed as a lower hazard than diesel, hydrogen or battery chemicals); it can be produced and stored on site or distributed by pipeline or road tanker.
  3. To turn the liquid air back to gas, simply apply “environmental heat” (anything warmer than -196C). If you do this in a confined space, i.e. inside the cylinder of an engine, the result is high pressure air (now in a normal gaseous state) which can be used to power a vehicle (or a static generator). The engine exhausts cold air back to the environment.

Harnessing ‘wrong time’ energy

We can therefore produce, store and transport energy as liquified air for use in zero emission vehicles or other zero emission engine applications. By harvesting energy from intermittent renewables (i.e. wind farms) to liquefy the air, we can in fact capture and ‘warehouse’ energy which would otherwise be thrown be away.

As we move to a low carbon grid, storing and managing so-called ‘wrong-time’ energy outside of the traditional electricity grid has been shown to reduce the infrastructure investment required by as much as £20bn in the UK alone.