The knock on renewable power generation is that it doesn’t reliably supply energy around the clock. Solar shuts down after dark and turbines don’t run when winds are calm. Currently, fossil-fuel power plants must serve as a back-up, which negates the benefits of “green” energy.
Large-scale energy storage is another alternative, but lithium-ion batteries are expensive, pumped hydro only works near mountains, and devices like massive-flywheels are unproven. A system based on compressed and liquefied air may prove to be a more-viable option.
Highview Power, a London-based developer of long-duration energy storage systems, has been awarded a £10 million ($12.5 million) grant from the United Kingdom’s Department for Business, Energy & Industrial Strategy for a 250 MWh facility based on air as the storage medium. In addition, the company recently received a £35 million ($44 million) investment from Sumitomo Heavy Industries to help fund the project.
How it works
In Highview Power’s cryogenic energy storage and generation system, ambient air is first drawn in, filtered and dried, then cooled via a set of compression and expansion stages until the air liquefies at -196° C (-320˚ F). The process is based on the Claude thermodynamic cycle. Liquid air is efficiently stored in insulated vessels at low pressure.
When power is required, liquid air is drawn from the tanks, pumped to high pressure, heated and expanded. Exposure to ambient temperatures causes rapid re-gasification and a 700-fold expansion in volume, and the resulting high-pressure gas is used to drive turbine-generators that produce electricity without combustion. Exhaust is merely clean, dry air.
Efficiency is enhanced by adding heat and cold storage banks that capture and hold waste energy from the compression and generation processes. Officials said plants based on this design will operate at about 60% efficiency in a standalone configuration. That could increase to around 70% efficiency by tapping into nearby sources of waste industrial heat and cold, such as from steel plants or LNG facilities.
The technology draws on established processes from the turbomachinery, power generation and industrial gases sectors. Equipment is readily available from large and established OEMs, using off-the-shelf components with proven performance in many applications, said Highview officials. The plant is expected to last at least 30 years.
Other benefits include no geographical constraints, unlike pumped hydro or compressed-air storage in underground caves. The system requires a relatively small footprint and is completely modular and scalable. Highview’s CRYOBattery plant can reportedly be designed to deliver anywhere from 20 MW/80 MWh to more than 200 MW/1.2 GWh of energy, at half the cost of lithium-ion batteries. The company said that at approximately £110/MWh ($0.137/kWh) for a 10-hr, 200 MW/2 GWh system, the CRYOBattery offers a competitive levelized cost of storage for large-scale applications.
Grid operators are turning to long-duration energy storage to improve power generation economics, balance the grid, and increase reliability. At giga-scale, CRYOBatteries paired with renewables are said to be equivalent in performance to — and could replace — thermal and nuclear baseload power.
Construction of the CRYOBattery facility outside Manchester is expected to start later this year and enter commercial operation in 2022. It will use existing substation and transmission infrastructure.
Javier Cavada, Highview Power CEO said, “This new cryogenic energy storage plant will deliver much needed long-duration energy storage and provide valuable services to the National Grid. We are delighted to have been chosen to assist the U.K. in achieving its goal of a 100% clean, carbon-free energy future.”
We are on a fast-track to develop our systems around the globe, and this partnership will help accelerate momentum in the numerous markets, added Cavada. Highview is moving ahead on other sites in the U.K., as well as in continental Europe and in Vermont in the U.S.
U.K.’s Energy and Clean Growth Minister Kwasi Kwarteng said, “This revolutionary new CRYOBattery facility will form a key part of our push towards net zero, bringing greater flexibility to Britain’s electricity grid and creating green collar jobs in Greater Manchester. Projects like these will help us realize the full value of our world-class renewables, ensuring homes and businesses can still be powered by green energy, even when the sun is not shining and the wind not blowing.”