Project Rassau in Wales designed to play a key role in National Grid’s innovative approach to managing the stability of the electricity system in response to the rapid growth of renewables

LONDON – 15 February 2022 – Quinbrook Infrastructure Partners (“Quinbrook”), a specialist global investment manager focused on renewables, storage and grid support infrastructure, announced today that it has completed construction and commissioning of a new synchronous condenser installation at Rassau, in Ebbw Vale, South Wales. The Rassau Synchronous Condenser is expected to support the stable decarbonisation of electricity supply as the UK rapidly increases the uptake of variable renewables in the drive to Net Zero (1).

Quinbrook partnered with Welsh Power in the development of the project from concept stage and with Siemens Energy for the construction of Rassau, which can now provide multiple grid support services including: inertia to strengthen the grid; short circuit power to ensure a reliable operation; and reactive power for voltage control (2). Siemens Energy committed to the use of local contractors and specialists during construction and since the commencement of civil works in September 2020, more than 300 personnel have been employed on site (3).

We view the UK’s ‘Net Zero’ transformation as an unprecedented investment opportunity with a diverse array of attractive thematics. Quinbrook targets the next generation of critical infrastructure investment that arises directly from the maturation of renewables as the dominant source of power in the UK. Crucially, our ‘whole of system’ approach puts the emphasis on addressing critical system needs and enablers. By delivering innovative and high-impact investments such as the Rassau Synchronous Condenser, our aim is to enable more renewables capacity to be built in the UK, thereby directly contributing to carbon emissions reduction and real progress towards Net Zero. Rassau is an excellent and timely example of how the energy transition has moved well beyond wind and solar. Additionally, by creating substantial employment opportunities and investment in the communities around the locations of Rassau and the wider Pathfinder portfolio we are proposing, we have the ability to directly support the UK Government’s levelling up agenda to reduce geographic inequality across the country.

Rory Quinlan
Co-founder and Managing Partner

Historically, grid stability in the UK’s power systems has been maintained by large synchronous power plants predominantly fueled by carbon-intensive coal and gas. These older fossil plants are being phased out and non-synchronous renewable generators, such as wind and solar, pose new reliability challenges as they do not possess the same grid stabilising properties. Due to the rapid proliferation of renewables across the UK, National Grid launched the Pathfinder Programme to source new ways to provide critical grid stability services (4). Rassau will now offer these services to National Grid using the synchronous condenser technology which operates on a continuous 24/7 basis (5).

National Grid’s Stability Pathfinder program offers indexed, long-term contracts to secure essential grid support services from projects like Rassau. The projects that secured a contract in National Grid’s Phase 1 of the Pathfinder Programme (6) are expected to collectively save consumers up to GBP 128 million over six years (7).

The Rassau synchronous condenser project adds to Quinbrook’s recent investments in UK companies all strategically supporting the energy transition including Flexitricity and Habitat Energy and solidifies Quinbrook’s early move into the supply of critical flexible capacity, storage and grid support infrastructure that enables more variable and weather-dependent renewables capacity to be safely accommodated on the UK power grid.

Alastair Fraser, Chief Executive of Welsh Power commented, “The innovative technology solution at Rassau is the first of many such facilities needed to manage grid stability as we transition to Net Zero. Welsh Power’s partnership with Quinbrook allows us to play an exciting role in the development of this market and I am proud of the whole team effort needed to deliver this groundbreaking project from concept to operation in two years.”

Steve Scrimshaw, Vice President, Siemens Energy UK&I said: “Decarbonisation is at the heart of Siemens Energy’s strategy and we are constantly looking for new and innovative ways to help reach net-zero. The integration of renewables brings many environmental benefits, but it can also bring some technology challenges such as balancing grid stability and resilience. By working with our partners National Grid, Quinbrook and Welsh Power, we’re proud we’ve been able to deploy an innovative solution that brings local value and tackles the important task of decarbonising our energy systems.”


  3. Rassau Monthly Construction Report, November 2021
  7. Reuters Business News, “National Grid agrees £328 million of contracts for stabilising UK electricity system”, January 2020


About Welsh Power

Welsh Power is an employee-owned business providing development and asset management services to flexible generation, storage, and grid stability markets.

About Quinbrook Infrastructure Partners

Quinbrook Infrastructure Partners ( is a specialist investment manager focused exclusively on renewables, storage and grid support infrastructure and operational asset management in the US, UK and Australia. Quinbrook is led and managed by a senior team of power industry professionals who have collectively invested c.USD 8.2 billion equity in energy infrastructure assets since the early 1990s, representing a total enterprise value of c.USD 28.7 billion or 19.5 GW of power supply capacity. Quinbrook has completed a diverse range of direct investments in both utility and distributed scale onshore wind and solar power, battery storage, reserve peaking capacity, biomass, fugitive methane recovery, hydro and flexible energy management solutions in the US, UK and Australia.

Media Contact:
Jennifer Pflieger
[email protected]
+1 (212) 446-1866

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