Our First Augmentation Project Is Underway Now, But It Was Designed Years Ago
A conversation with David Harris, Senior Asset Manager at Gore Street Capital
At Stony (Milton Keynes, UK) and Ferrymuir (Scotland, UK), Gore Street Capital is delivering the first battery augmentation projects within the Gore Street Energy Storage Fund portfolio.
Over the coming months, both sites will transition from one-hour battery systems to two-hour duration assets, increasing the amount of renewable energy they can store and dispatch to the grid. New equipment is arriving on site, civil works have been completed, and installation activities are progressing.
While the physical transformation is happening today, the foundations for these projects were laid years ago.
In many ways, the augmentation projects began long before the first piece of equipment arrived on site.
We spoke with David Harris, Senior Asset Manager at Gore Street Capital and lead on the project, to learn more about what augmentation involves, why these assets were selected, and how decisions made years ago are helping shape the project today.
Reflecting on the project, David explained:
“Successful augmentation doesn’t start when construction begins. It starts with decisions made during the original design of the asset.”
What is Battery Augmentation?
Put simply, battery augmentation involves increasing the energy capacity of an existing Battery Energy Storage System (BESS).
For Stony and Ferrymuir, the result is a battery system capable of storing and delivering energy for longer periods, allowing it to respond to changing market conditions and grid requirements.
As battery markets evolve, assets must evolve with them. Augmentation provides a way to enhance an existing site’s capabilities while making use of infrastructure that is already in place.
Why Now?
When Stony and Ferrymuir were originally developed, one-hour battery systems aligned well with the market opportunities available at the time.
Since then, the battery storage sector has matured significantly. Longer-duration storage assets are playing an increasingly important role in energy trading and wider system optimisation, creating new opportunities for battery operators.
Augmentation allows existing assets to adapt to these changes, ensuring they remain well-positioned to deliver value over the long term.
But for Gore Street Capital, the most interesting part of this story isn’t that augmentation is happening now.
It’s that these sites were prepared for it from the very beginning.
Designing for Tomorrow’s Market
The opportunity to augment Stony and Ferrymuir wasn’t created when the contract was signed in November 2025. It was created when the designs were completed in June 2022.
These sites were selected for future expansion from the beginning. They were designed with the space, infrastructure and flexibility needed to support additional capacity if and when market conditions justified it.
That forward-thinking approach is now proving its value.
By designing Stony and Ferrymuir with future augmentation in mind, Gore Street Capital retained the flexibility to expand capacity when the timing was right. Rather than committing all capacity from the outset, the sites were designed to evolve alongside developments in technology and project economics. Based on Gore Street Capital’s internal research and pricing analysis, battery costs decreased by over 60% between the original EPC contracts and the augmentation programme, generating savings of more than £200,000/MWh for the addition of the second hour of duration.1
“Good design doesn’t just make augmentation possible, it gives us the ability to choose the best moment to do it.”
Turning Design into Delivery
Equipment is arriving, installation works are progressing, and the augmentation programme has moved from concept to construction. The project is being delivered in partnership with Nidec, whose extensive experience in battery energy storage systems has helped turn years of planning into on-site progress.
The programme officially began with contract signing in November 2025, followed by engineering, design and procurement activities. Working closely with Nidec, Gore Street Capital developed a delivery programme designed to balance speed of installation with the operational impact on the sites. By carefully sequencing the works, the team has sought to minimise revenue loss from reduced availability while bringing additional capacity online as efficiently as possible.
Civil works have now been completed, with testing and commissioning expected later this year. Current timelines anticipate completion of Stony A in October 2026, Ferrymuir in November 2026 and Stony B in December 2026.
As Gore Street Capital’s first augmentation projects, Stony and Ferrymuir represent more than an increase in battery capacity. They demonstrate how long-term thinking at the design stage can create value throughout an asset’s lifecycle.
Looking back on the journey from design to delivery, David summarised the project in one sentence:
“Our first augmentation project may be underway today, but the decisions that made it possible were made years ago.”
Over the coming months, further updates on these projects will be shared. Follow Gore Street Capital on LinkedIn and subscribe to the YouTube channel for future site updates and how the augmentation programme is being delivered.
Sources / Further Information:
- Gore Street Capital’s internal research and analysis, comparing EPC contract quotations received in 2022 with augmentation programme costs in 2025.
- This article is provided for information purposes only. It does not constitute investment advice, nor an offer or invitation to buy, sell or subscribe for shares in Gore Street Energy Storage Fund plc. Capital is at risk and the value of investments may go down as well as up. Past performance is not a guide to future performance. This article contains forward-looking statements, including expected project timelines and outcomes, which are subject to risks and uncertainties; actual results may differ materially and Gore Street Capital undertakes no obligation to update them. Certain figures are estimates based on internal analysis and third-party data and may be subject to change.
