A hybrid Liquid Air Energy Storage (LAES) system is being developed to respond to grid frequency events within 1 second.
The system – designed and developed in the UK by Highview Power Storage – has been awarded funding of £1.5 million from Innovate UK, the UK’s innovation agency.
The funding will enable Highview to use supercapacitors and flywheel technology to create the hybrid LAES system and test its performance and viability.
Gareth Brett, CEO of Highview, said: “A hybrid LAES system provides the powerful combination of instant start and long duration storage and is an important step for Highview as it broadens the range of services which LAES can supply and will help enhance the economic case for its adoption.”
The hybrid LAES system will be added to Highview’s 5MW/15MWh pre-commercial demonstration plant at Viridor’s Pilsworth landfill gas plant in Bury, Greater Manchester, which is due online at the end of the year.
The hybrid LAES system is expected to be operational by mid-2018.
Highview has been gaining experience in this field since it opened its first pilot plant (350kW/2.5MWh) in 2011. This was connected to the grid at a biomass plant in Slough, UK, until 2014.
Whilst LAES can be compared to other large-scale technologies such as pumped hydro or compressed air energy storage, it does not require specific geography and can be located at the point of demand.
The technology works by taking off-peak or excess electricity and using it to turn air into a liquid by refrigerating it to -196°C and storing it in insulated tanks at low pressure. When power is required, liquid air is drawn from the tanks and pumped to high pressure. Heat harnessed from the liquefaction process is applied to the liquid air via heat exchangers and an intermediate heat transfer fluid. This produces a high-pressure gas in the form of air that is then used to drive the turbine and create electricity.
Georgina Penfold, CEO of the Electricity Storage Network, commented: “Battery energy storage has made the headlines recently, but other electricity storage technologies are also of high value. This Liquid Air Energy Storage solution is not only applicable to the British electricity system, but shows great potential for exporting British expertise into international markets.”
• In the USA, Alphabet Inc’s research lab – which hatched Google’s driverless car almost a decade ago – is developing a system for storing renewable energy involving vats of salt and antifreeze. Codenamed ‘Malta’, the project is at the ‘de-risked’ stage, and the team is looking for partners to build, operate and connect a commercial-sized prototype to the grid.
According to Bloomberg News, the system looks like a miniature power plant with four cylindrical tanks connected via pipes to a heat pump. Two of the tanks are filled with salt, and two are filled with antifreeze or a hydrocarbon liquid. Using excess energy from wind farms and solar panels, the plant heats up the salt and cools the antifreeze. When electricity is required, the process is reversed and the hot and cold air rush toward each other, creating powerful gusts that spin a turbine.