Energy storage projects improving the grid's reliability in the UK

Overview of projects:

With the UK government's mission to have a net zero power grid by 2030, integrating battery energy storage technologies with the grid for more efficient and flexible energy dispatchability has become a major priority.

The Blackhillock phase one 200 MW / 400 MWh, Blackhillock phase two 100 MW / 300 MWh, and Kilmarnock South 300 MW / 600 MWh battery energy storage systems (BESS) deliver stability services using transmission-connected batteries, supporting the UK’s transition to a zero-carbon energy network by preparing the grid for an increased supply of renewables.

Wärtsilä retrofitted Zenobē’s 100 MW Capenhurst BESS with its GEMS control and optimisation platform, enabling advanced UK grid‑code compliance, unlocking new revenue streams, and future‑proofing the asset as market and regulatory requirements evolve.

The 68 MW / 130 MWh Shetland Standby Project will enhance energy security, reduce emissions, and support the Shetland Islands’ transition to a cleaner, more resilient power system.

Reliability coupled with innovation at Blackhillock and Kilmarnock

The energy storage systems are delivered under National Energy System Operator's (NESO) NOA Stability Pathfinder Programme to improve the long-term stability of the electricity system. Owned by Zenobē, the systems assist grid operators in the management of challenges related to balancing supply and demand, power stability and constraints.

The systems provide stability services to the NESO, including short-circuit level and true synthetic inertia, which are essential for the grid to function efficiently as fossil fuel plants phase out.

The Blackhillock project is built with Wärtsilä’s Quantum, a fully-integrated, modular and compact ESS. Kilmarnock South is the first project to be delivered with Quantum High Energy, a next-generation energy storage system with advanced safety features and enhanced energy density. The systems are robustly supported with Wärtsilä’s sophisticated software that can monitor the sites in real-time and optimise operations.

Not all PPCs are created equal: intelligent control software is critical for performance and market access

Wärtsilä retrofitted Zenobē’s 100 MW Capenhurst battery energy storage system with its GEMS control and optimisation platform to keep pace with rapidly evolving UK grid‑code requirements. The upgrade enabled advanced, stateful grid‑code compliance, including De‑load functionality, while improving response speed and operational precision in dynamic frequency markets. By replacing legacy control systems, the site gained greater flexibility, scalability, and support for multi‑tenant operation behind a shared point of interconnection. Delivered in close collaboration with Zenobē, the retrofit was completed quickly, minimising downtime and securing full regulatory approval. As a result, the Capenhurst site is now future‑proofed, compliant, and better positioned to access high‑value ancillary service revenues over its full lifecycle.

Power without interruption on Shetland Islands

The battery system will enable the Lerwick Power Station to move into a standby role, cutting fossil fuel use and helping integrate more renewable energy from Shetland’s abundant wind resources. In the event of an outage or planned maintenance on the transmission line to mainland Scotland, the battery energy storage system will maintain uninterrupted power to Shetland’s homes and businesses.

The battery system features a range of innovative technologies: it will deliver Distribution Fault Ride Through (DFRT) capabilities and standby solution services to support Shetland's mainland interconnector. These capabilities ensure grid stability in the face of transmission faults by keeping the system powered without interruption.

Ensuring fast and intelligent responses with GEMS

Our GEMS platform manages the complete energy storage systems. The software eases network constraints by importing electricity at times of peak renewable generation. At Blackhillock and Kilmarnock, GEMS’ data-based intelligence enables Zenobē to participate in the most valuable UK electricity markets.

Customer	Zenobē
Site size	Blackhillock 1, 200 MW / 400 MWh Blackhillock 2, 100 MW / 300 MWh Kilmarnock South, 300 MW / 600 MWh Shetland, 68 MW / 130 MWh Capenhurst, 100 MW / 100 MWh
Site location	Scotland and England, UK
Solutions/Applications	GridSolve™ Quantum, Stability services, GEMS control and optimisation software, grid integration support
Scope of services	Engineered Equipment Delivery (EEQ)
Delivery	2024-2026

TIME recognised Wärtsilä in their 2025 edition of Best Inventions for our work at the Blackhillock site in Scotland, a first-of-its-kind energy storage system in the UK.

2025 Awards for Blackhillock:

TIME Magazine Best Inventions
Energy Storage News Award - Best UK Project over 100 MW
Energy Storage News Award - Best EU Project over 100 MW
Energy Storage News Award - Grid-scale Standalone Project of the Year
pv magazine Award - Projects
Power Magazine - Energy Storage Award

This is what we achieved

1.4

GWh of energy storage capacity

£170

million savings expected for consumers over the next 15 years (Blackhillock project)

2.6

million tonnes of CO₂ prevented from entering the atmosphere over the next 15 years (Blackhillock project)

“-
Our batteries at Blackhillock are the first to use advanced power electronics to enable a much higher uptake of renewable power on the grid. This dramatically reduces costs to consumers and increases reliability.

- James Basden, Founder and Director, Zenobē

“-
Retrofitting our Capenhurst facility with GEMS has made the site future ready, enabling our system to keep pace with evolving UK grid requirements. We value the flexibility and reliability of the GEMS platformand the expertise Wärtsilä brings to getting projects finished efficiently.

- Simon Wood, Global Director of Operations - Network Infrastructure, Zenobē

How we did it | Case Blackhillock

Challenge

Allow for integration of nearby offshore wind energy projects with the UK grid
Provide stability services as the UK phases out fossil fuel plants
Meet network demand and customer cost expectations

Solution

Provide short-circuit level and true synthetic inertia to the National Grid Electricity System Operator
Deliver inverter technology that pushes the technical boundaries of the type of support that batteries can provide to the grid
Supply Wärtsilä’s energy storage management software including the GEMS Fleet Direct and Power Plant Controller to optimise operations, while easing network constraints by importing electricity at times of peak renewable generation

Benefit

Facilitate the UK’s transition to net-zero by enabling more wind power onto the transmission network
Improve the long-term stability and reliability of the electricity grid
Support the UK’s energy independence and lower consumer energy bills

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