CARES - Compressed Air Renewable Energy Storage

Project of Common Interest in Cheshire, UK

Current Status of the Project

Purpose of Each Plant

As stated elsewhere, this project consists of two plants: one at 40MW, 200MWh and the other at 500MW, 2.5GWh. These will be in different Special Purpose Vehicles (SPVs), the first of which is Storelectric Cheshire Limited.


The purposes of the 40MW plant include:

  • Demonstrating the technology profitably;
  • Enabling the financing of the 500MW plant;
  • Providing balancing and ancillary services to the distribution grid.


The 500MW plant will do the same for the transmission grid.


Current Status

We have now completed the technical feasibility of the 40MW plant in conjunction with Costain and Fortum, the former undertaking static modelling including various sensitivity analyses, and the latter undertaking dynamic modelling using their industry-leading Apros system. To quote from the Executive Summary,













We are now applyinf gor CCEF funding of a Study to take both plants to “shovel ready”, the 40MW by mid 2020 and the 500MW by the end of 2023. We will follow with a Works application to part-fund the construction of the smaller plant; if granted without imposing any delay, then it should be operational mid 2022; the larger plant would then be operational in 2027. “Shovel ready” includes:

  • Front End Engineering Design (FEED) to the point of letting contracts;
  • Obtaining planning permission from the local authority (40MW) and the Planning Inspectorate (500MW);
  • Obtaining a grid connection offer from the Distribution Network Operator (DNO – Scottish Power Energy Networks);
  • Completion of cavern preparatory work (for 40MW, further analysis; for 500MW, design);
  • Grid connection studies to the distribution (40MW) and transmission (500MW) grids;
  • Detailed design.

We will undertake a public consultation with each planning application, details of which will be published either on this website or on the SPV’s website (to which this site will link) at the appropriate times.

“The system is robust and works well under all the sensitivities tested during this study. For the base case the round trip (i.e. grid-to-grid) efficiency calculated was 63.1%, with a range of 61% to 63.5% depending on findings of further study work (particularly the thermodynamic modelling of the caverns) and prevalent ambient conditions. The dynamic simulation conducted by Fortum show good correlation with the results of this study stating efficiencies of 62 to 64%. Previous works by Oswald Consultancy and Siemens put the efficiency at 62.3 and 62.7% respectively, albeit the process setup was marginally different.


“It is expected that further improvements to the efficiency should be achievable during the Front End Engineering Design Phase, with a close collaboration between the heat storage, compressor and expander suppliers.”


March 2018 Update

We have started wildlife/habitat surveys, consultations with on planning, technical validation of the TES CAES technology by both static and dynamic modelling with numerous sensitivity analyses, and a feasibility study on converting two ethylene storage caverns to use for CAES. The official PCI annual report is here. A plain text simple update report is here.



A 500+40MW adiabatic Compressed Air Renewable Energy Storage project in Cheshire, UK, providing large scale and long duration (5 hours) energy storage efficiently and without emissions



(+44) 7910 020 686


Project promoter: Storelectric Limited


Licensing the TES CAES technology from TES CAES Technology Limited


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