A big issue facing wind and solar energy systems is the intermittent nature of production when the sun is down or the wind isn't blowing, and the need for renewable energy storage during peak generation (in order to make it available for later use during peak demand) is driving innovation in battery technology.
One inventor believes the solution could be found in his 'frozen air' battery system, which uses energy from peak production times to chill air to a liquid state, and then when needed, vaporizes the liquid and uses the released energy to turn turbines.
Peter Dearman, an inventor working out of his garage in Hertfordshire, UK, originally developed his "cryo-power" technology to power vehicles, but it turns out that his invention just might be the ticket to efficient renewable energy storage.
Dearman's 'frozen air' energy process begins during off-peak hours, when the electricity generated by wind or solar plants is used to chill air (after removing the water vapor and CO2) down to -310F, turning it into a liquid state. The resulting 'liquid air' is stored in a vacuum flask, and when power demand rises, that liquid gets warmed to ambient temperature. The warming of the liquid air vaporizes it and the resulting increase in pressure drives a turbine for generating electricity.
According to the BBC, Dearman says he felt that his 'liquid air' technology could compete with other energy storage systems because it isn't reliant on traditional (and sometimes scarce) materials in its construction.
"I have been working on this off and on for close on 50 years. I started when I was a teenager because I thought there wouldn't be enough raw materials in the world for everyone to have a car. There had to be a different way. Then somehow I came up with the idea of storing energy in cold." - Dearman
A pilot system for storing energy using Dearman's technology has been developed and operating for several years at a power station in Slough, thanks to Highview Power Storage, which is working to scale up the technology to a storage system that can be used on the grid.
Highview admits that the current process is only about 25% efficient, but believes that once the systems are produced at scale, the conversion could be up to 70% efficient.