Shannonbridge B: Re-building the inertia backbone for Ireland

At Shannonbridge B in central Ireland, on a site previously associated with thermal generation, we have commissioned what we consider one of Europe’s most consequential demonstrations of how a high-renewables grid actually works in practice. A 160 MWh battery energy storage system combined with a flywheel-based synchronous condenser delivering approximately 4,000 MWs of rotating inertia. Both assets are coordinated by a single Siemens Energy controller. One contract, one site, one accountability path to the system operator. 

The story of Shannonbridge B is not only the story of a battery, it is the story of what replaces coal and what every system targeting 70% to 80% non-synchronous renewable penetration will have to build in some form before the end of the decade. 

Colocation thesis  

EirGrid has set one of the most ambitious non-synchronous renewable penetration targets in Europe, moving the limit towards 80%. The target although is technically achievable, it is also physically demanding: as wind and solar displace synchronous generation, the grid loses the rotating mass that has, for a century, set frequency, damped disturbances, and held the system stable through faults. The renewables build-out itself does not solve the problem and requires innovative solutions to make sure the system stays balanced. 

Shannonbridge B is engineered to put both inertia and fast active-power response back into the network – without burning fuel. The flywheel-based synchronous condenser delivers approximately 4,000 MWs of rotating inertia continuously, exactly as a thermal turbine would, together with short-circuit power for fault ride-through. The 63MW/158 MWh battery delivers fast frequency response, broader system services, and energy-shifting capability under EirGrid’s DS3 System Services framework. The two assets are coordinated by a single integrated control architecture, so they behave as one operating asset rather than two co-located plants 

Inertia services exist in many markets such as the UK & now also Germany. Fast frequency response exists in most markets globally to ensure system stability, typically provided by BESS. But what makes Shannonbridge B special is that all of these services come from a single integrated asset, and the controller decides in real time which physical layer responds to which event. 

When the grid experiences a sudden frequency excursion, the synchronous condenser arrests the rate of change of frequency through its physical inertia with no controller intervention required. The battery then delivers sustained active power against the disturbance, holding the frequency until slower assets take over. Voltage support comes from both layers. Fault current contribution comes from the SynCon. Black-start readiness is preserved across the site. 

For a system operator, this is the closest thing in commercial service today to a “synchronous unit replacement”: a single asset performing the system functions a coal plant used to perform, without the emissions, without the fuel exposure, and without the fixed dispatch profile that makes thermal plants increasingly hard to economically justify in renewables-heavy markets. 

The commercial case is structural rather than speculative. EirGrid’s DS3 framework contracts multi-year revenue for synchronous inertial response, fast frequency response, and the wider system services stack – exactly the services Shannonbridge B is configured to deliver. The site is positioned to monetize against multiple service categories from a single interconnection, building the kind of revenue stack that standalone merchant batteries in liquid markets are working considerably harder to assemble piece by piece. 

Three properties matter for any asset owner evaluating a similar configuration; 

Hybridization compresses capital cost as it allows for shared interconnection i.e. behind the meter through a singular connection. This configuration not only helps in reducing interconnection costs as its shared between both assets, but it also greatly helps avoid long interconnection queues. Interconnection queues across most countries remain a major bottle neck for developers & IPPs, utilizing existing plant connections to add a BESS to a gas fired plant or a synchronous condenser plant helps in avoiding the queues and also minimizing costs through shared site infrastructure, shared controls – thereby  reducing total project cost relative to two separate assets by a meaningful margin, and shortening the path to commissioning. 

The revenue stream is durable as Synchronous inertia and fast frequency response services scales with renewable penetration, not against it. As Ireland approaches 80 percent SNSP, what Shannonbridge B B provides becomes more valuable, not less. 

Developers and owners 

At Lumcloon Energy, we see Shannonbridge B as a strategically important project within Ireland’s evolving energy landscape.  Large-scale storage is no longer a complement to the grid; it is becoming a structural requirement. “Our focus has always been on developing infrastructure that supports the long-term evolution of the Irish electricity system,” said Nigel Reams, CEO of Lumcloon Energy. “Shannonbridge B demonstrates how storage, grid stability technologies, and strategic site selection can come together to create projects that are not only commercially viable, but fundamentally important to enabling Ireland’s renewable energy future.” 

For Hanwha Energy, Shannonbridge B is part of a broader portfolio strategy focused on scaling integrated energy solutions that combine storage, grid support capabilities, and renewable integration. Hanwha Energy is the majority shareholder in Shannonbridge B and views the project as a strategic asset within its growing international platform of advanced energy systems. Shannonbridge B strengthens the company’s exposure to integrated grid services and technology combinations that are expected to become increasingly important globally. Internationally, Hanwha Energy is expanding its position in storage-led and hybrid energy markets, with a multi-gigawatt development pipeline across Europe.  

We delivered a successful commissioning for Shannonbridge B and continue to lead in this hybrid configuration, Our integration accountability & engineering discipline is unmatched as we design, build and orchestrate a flywheel-based synchronous condenser and a battery energy storage system as one operating asset, under a single control architecture, with a single accountability path back to the system operator. We bring the rotating-machine heritage that the synchronous condenser side requires. We bring the Qstor™ storage solutions and the Omnivise control platform that the storage side requires as well as the integration logic that turns two physical layers into one asset the system operator can rely on. 

Gaurav Visvanathan is head of market applications BESS Europe, Siemens Energy Global GmbH & Co. KG.