The four “storage” elements are innovative and pioneering. Typically electricity storage has used battery packs with units such as the Tesla Powerwall being the most widely promoted. RE/SOURCED does more – it has identified four storage technologies (including batteries) that will work in parallel. The RE/SOURCED project is testing the suitability of these systems and also assessing how effectively the 400V DC backbone can support the integrated working of these technologies.
Flywheel technologies were originally anticipated to be included in the “storage mix”. However, due to COVID supply chain challenges, their acquisition is currently on hold.
Pumped Water Storage
The old Transfo coal fired power system incorporated a 43m high water tower to provide the facility with a ready supply of pressurised water. Although the storage tank was refurbished in 2020, it needs to be re-sealed for its new use through RE/SOURCED. Existing piping and systems will be reused in keeping with the project’s Circular Economy principles. Given its height, it was estimated to have the potential to generate up to 11kW and it was proposed to use an in-line small scale turbine to generate electricity for shorter periods, for example for peak shaving. In addition, the pumped storage demonstrator makes a very important educational contribution to the project.
However, while incorporating pumped storage is a goal of the project, the use of this technology has proven to be problematic to include in practice. Tenders have been issued three times but have generated no responses from potential suppliers, despite indications from them that the opportunity is of interest. Feedback suggests that there are two factors at play - the tender value is too small to be attractive to firms that might provide the equipment (especially when compared to other opportunities in the current buoyant market) and administrative effort required to respond to a formal public procurement process is too great.
The project is therefore having to consider whether it will be feasible to include this storage element going forward. It may be that its provision is achieved through another funding route (e.g. using technical or scientific research funding) at a later date
Hydrogen is part of climate discussions for hard-to-decarbonize sectors and as a store of electricity. Specifically, it is increasingly being proposed as a carbon-free energy source for transport. However, energy is required to produce the Hydrogen and the generation process has tended to use fossil fuels. This has resulted in significant energy emissions. Hydrogen produced using carbon fuels is termed “blue hydrogen” while that created using Renewable sources is termed Green Hydrogen
RE/SOURCED will produce more electricity than local users can consume at certain times of the year (notably sunny and windy days). It is exploring whether Hydrogen production might be possible as a storage medium.
Second Life Batteries
Battery storage is presently the most widely used technology for storing renewably generated electricity. These are typically Lithium Ion units and are increasingly being offered commercially.
However, unlike typical commercial systems that use new batteries, RE/SOURCED will use second life batteries (that have previously been deployed for transportation etc) supporting its Circular Economy goals. While these batteries are no longer suitable for transport use (either because the storage capacity of the battery pack has been superseded or as the packs have become less efficient through use) they will be very suitable for the storage needs of the TRANSFO site.