Most of the advances in energy storage rely on traditional battery technologies, but a UK company is commercializing a different approach – a utility-scale system that draws and stores energy from frozen air.
UK-based Highview Power Storage has developed a proprietary process that uses cryogenic (liquefied) air as its principal component and liquid nitrogen as the working fluid and media for storing and/or transporting energy.
"This is one of only a few technologies that can be delivered today at the 50-100 megawatt (MW) scale with hundreds of megawatt hours of energy stored. Critically, the technology relies on mature components, but assembled in a novel process, which significantly reduces the technology risk," says Highview.
Liquid air technology is based on the principles of cryogenics – which govern how certain elements behave at very low temperatures.
The key to the Highview Cryo Energy System is liquefied air or liquid nitrogen (which is 78% of air), which can be stored in large volumes at atmospheric pressure, and is a very common commercial product. It can be transported or produced on site for large operations.
Highview’s approach extracts carbon dioxide and water vapor out of the air and then super-chills it to minus 321 degrees Fahrenheit. This creates liquid nitrogen that is then stored in massive vacuum flasks. When the substance is heated, it returns to a gas state – generating enough force to drive turbines that generate electricity, the company says.
Wind and solar energy are used to suck the air into compressors.
Besides energy storage, the technology can convert waste heat to power from co-located biomass, industrial or utility plants, and deliver cold air – air conditioning, data center cooling or refrigeration.
Since 2010, a 300-kilowatt (kW) pilot installation has been hosted by UK utility SSE at Slough Heat & Power, where waste heat is used as a source for nitrogen. It’s the world’s first liquid air energy storage plant.
BBC’s Energy Live News program recently did a segment on this, which you can watch in this video:
During the segment, High Power Storage engineer Stuart Nelmes acknowledges that current battery technologies are more efficient, but liquid nitrogen storage is very effective at converting low-grade waste heat into power. It’s also more mature, scalable and adaptable to today’s electric grid. Highview gave a presentation on this in May.
Based on its initial success in Slough, the company is looking toward a 10-megawatt (MW) commercial-scale demonstration at a cost of $900 to $1,800 per kW. In comparison, the capital cost of a high-density NaS battery is $3,100-$3,300/kW, says Highview.
As in the Slough pilot installation, Highview’s strategy is to co-locate its technology at industrial or utility power plants where it can draw on waste heat for its process.
It has two commercial products: Cryo Energy System, which offers modular storage scalable from a few MW up to hundreds of MW; and Cryo GenSet, which it pitches as a zero-emission alternative to a diesel genset or gas peaking plant.
Founded in 2005, Highview is backed by $18 million in private equity and a $1.8 million grant from UK’s Department of Energy and Climate Change that’s supporting the pilot project in Slough.
In July, Highview signed a strategic partnership agreement with Messer Group, the world’s largest privately-owned industrial gases company. Messer has the exclusive right to market the technology to industrial gas markets in return for annual licensing fees and giving Highview access to its engineers to further development.
Also that month, the company signed with Basil Read Energy, one of the biggest construction, mining and energy companies in Africa, to bring the technology there.
Here’s Highview’s website:
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