UK BESS pipeline grows with 748 MWh Blackhillock approval and 349 MWh two-phase Sizing John expansion

UK developer Noriker Power has secured planning approval for a 349 MW/748 MWh battery energy storage system (BESS) to be built next to the Zenobe-developed Blackhillock BESS commissioned in early 2025.

The Scottish government’s Energy Consent Unit approved the BESS application submitted Blackhillock Flexpower Ltd, a company owned by Shires Stability – a wholly owned subsidiary of Noriker Power, according to the development website.

Planning documents for the Gibston Farm BESS detail a proposed development comprising 208 battery containers. The location in northeast Scotland places the energy storage system in a region with significant wind curtailment.

Gibston BESS would connect to SSEN Transmission’s Blackhillock substation, according to the latest Transmission Entry Capacity (TEC) register update from grid operator NESO. Blackhillock is a key substation on Great Britain’s transmission network, capable of carrying up to 1.2 GW and incorporating 400 kV and 275 kV infrastructure, as well as a high-voltage direct current (HVDC) converter station.

The TEC register lists a 349 MW grid connection date for the BESS project effective Oct. 29, 2027, connecting to the 400 kV network. Zenobe’s nearby Blackhillock BESS, which made headlines in early 2025 as the first BESS in the world to deliver true synthetic inertia and short-circuit level support, is connected to the 275 kV transmission network via the same substation site.

Sizing John Energy Storage Project: Two stage approach

Varco Energy (Varco), a UK-based BESS asset owner and operator backed by the Adaptogen Capital Battery Storage Fund, and the UK subsidiary of Fluence Energy, Inc. (NASDAQ: FLNC) have announced major progress on the Sizing John BESS,located within the Mersey Ring east of Liverpool, a region known for its acute grid constraints.

The companies confirmed that Phase 1 – a 57 MW / 137.5 MWh installation – has now entered full commercial operation. In parallel, Varco has launched Phase 2, selecting Fluence to expand the site with an additional 85.5 MW / 201 MWh, bringing the combined project to 142.5 MW / 348.5 MWh.

Designed to maximise both near-term and long-term system benefits, Sizing John adopts a two-phase development strategy. Phase 1 features a 2.4-hour duration, placing it among the longest-duration operational BESS assets in the UK. That capability allows the system to help ease regional congestion and dampen price volatility driven by rising renewable penetration.

Phase 1 is powered by Fluence’s Gridstack platform, delivering balancing and flexibility services to support local supply–demand dynamics. Construction of Phase 2 is already underway, with commercial operation expected in Q4 2026. The second phase will deploy Fluence’s next-generation Gridstack Pro 5000 technology, incorporating advanced grid-forming capabilities designed to independently regulate voltage and frequency for enhanced regional stability.

Grid-forming BESS deployments are becoming increasingly widespread worldwide. Grid-forming inverters mimic the voltage-source behaviour of synchronous machines, providing inertia-like response, frequency regulation, voltage control, and fault ride-through- all without reliance on rotating mass. As software-based systems, they require carefully designed control strategies and, in some cases, upgraded hardware to reproduce the dynamic behaviour of traditional electromechanical generators.

While grid-forming technology remains technically complex to implement and scale, regulatory frameworks are gradually evolving, and costs are becoming less of a barrier as the technology matures. Benefits such as lower maintenance, greater flexibility, and firmware-based upgradeability further enhance the long-term value proposition. However, the sector’s biggest hurdle is still real-world operational experience: grid-forming remains young, and the industry needs significantly more operating hours and performance data to build confidence and validate its full system value.

For Varco, Sizing John is its second project to enter operation, following Native River BESS, which began full commercial service in April 2025. Over the next 18 months, Varco expects to energise a further 250 MW of UK assets, with an additional 275 MW in its development pipeline—fully deploying capital from Adaptogen’s first fund.