CRYOBatteries help keep the grid stable as the share of renewable energy increases – and could pave the way for an electricity grid based entirely on sustainable energy.
The batteries store energy using liquid air and are made more efficient by clever use of the waste cold and heat created during the process. CRYOBatteries are relatively long-lasting (30-40 years) and easy to make and install.
We have the technology available, and suitable, to solve all of the energy challenges we are having—so let’s deploy renewable energy storage now.
Javier Cavada, CEO, Highview Power
In order to mitigate the climate crisis, electricity generation must shift from fossil fuels to renewable sources. But the amount of energy produced by these sources varies hugely across hours, days and weeks, and cuts to the number of large thermal power stations – such as coal, gas and nuclear plants – making the grid less stable.
Demand response software can make the grid more stable over seconds and minutes, while pumped-storage hydropower or batteries can cover supply shortages for a few hours. But these last two technologies have limitations on scale and cause some environmental damage. A 100% renewable electricity grid needs a low-cost energy storage solution that can be placed anywhere, can be scaled up and does not damage the environment.
Highview’s CRYOBattery meets these criteria. It stores energy through a three-stage process:
- Refrigeration: The CRYOBattery compresses and cools air until it becomes liquid, at -194C. Electricity is drawn from the grid to do this, and some of the heat produced as a by-product is stored for later use in the expansion stage.
- Storage: The liquefied air is kept in an insulated tank until energy generation is needed.
- Expansion: The liquefied air is evaporated and used to drive a turbine and generator as it warms up and expands – 1 litre of liquefied air expands to 700 litres of normal air. Some of the cold of the liquid air is captured during evaporation to make the next refrigeration cycle more efficient.
The CRYOBattery has a round trip efficiency of 60%, or 70% if a local source of waste heat can be used to help evaporate the liquefied air. This is less efficient than lithium battery storage, but for a large site the cost per kilowatt hour (kWh) of storage is much lower, its performance does not degrade over time (as happens with lithium batteries) and it mostly uses common materials such as steel and copper, rather than the lithium, cobalt, nickel and manganese used in conventional batteries. The CRYOBattery can also be sited anywhere, unlike pumped-storage hydropower, which needs lakes to store water.
Highview Power has spent over a decade researching and developing the CRYOBattery , ensuring the technology has been thoroughly proven before its introduction in large-scale plants. The company ran a 350 kW pilot CRYOBattery from 2011 to 2014 before building a 5 megawatt (MW) commercial demonstrator near Manchester, and is expecting to start construction on a 50MW CRYOBattery before the end of 2019.
Highview’s innovation is in the design of the overall system and the control software – the component parts such as storage tanks, refrigeration, pipes and turbines are all standard machinery already produced for other uses. This makes it relatively easy for Highview to scale up its business now that the technology is proven.
The immediate benefit of the CRYOBattery is in keeping the electricity grid stable, by charging or discharging as directed by signals from national grid operators and distribution network operators. The need for such services grows as the proportion of fossil fuel energy on the grid reduces, so energy storage is a key enabler of decarbonisation.
As renewable energy capacity increases in the future, it will become necessary to store surplus energy from sunny or windy periods for hours or days to balance out supply and demand; the CRYOBattery is an affordable scalable solution to this challenge, removing a major block to 100% renewable electricity.
Because the CRYOBattery is built using technology common in the oil, gas and power industries, it is also an opportunity to support manufacturing jobs in these areas during the move away from fossil fuels, helping to deliver a ‘just transition’.