Moneypoint synchronous condenser: Ireland’s great grid stabilizer

Aerial view of the Moneypoint plant in Ireland

Ireland finds itself in a similar situation to other countries now looking to advance progressive climate action targets and phase out coal while providing inexpensive energy and limiting their dependency on other nations.

This is what the World Energy Council coined the “energy trilemma” in 2015: How can we balance security, affordability and sustainability in our energy systems? Fortunately, Ireland has massive amounts of renewable energy just off its coast – wind, and more than enough of it to power their country many times over.

But there’s a catch.

“Imagine your electricity grid as a motorway,” says Katie Wall. “With conventional forms of generation, you won’t fall off that motorway. But drop those forms in favor of renewables, and suddenly your grid is a tightrope. At some point you’re going to lose your balance, right? And you’ll need a safety net.”

I’m standing with Wall on a grassy hillock in front of the Moneypoint Power Station, run by Ireland’s foremost energy company, the Electricity Supply Board (ESB), on the Mid-West Irish coast. The enormous blade of a wind turbine turns ponderously above us and the River Shannon is hardly a stone’s throw away.

Wall is ESB’s Lead Engineer for the first step in a visionary, multi-decade project called “Green Atlantic @ Moneypoint” that will radically transform the station into the country’s first green energy production hub.

Moneypoint will become the center for the construction and assembly of floating wind turbines, starting with 1,500-megawatt floating offshore wind farms (enough to power 1.6 million homes), and it will be converted into a station able to produce, store and provide power generation with carbon-free green hydrogen.

“We saw a clear opportunity to transition Moneypoint from being a cornerstone of the electricity system as a coal plant to being a cornerstone of a renewables future both for ESB and for Ireland,” says Jim Dollard, ESB’s Executive Director for Generation and Trading, during a video call from his home office in Dublin. “We’ve been very open in saying we’re ceasing burning coal, but we wanted to see this site repurposed. It’s a fantastic site. It’s a big site. It has a deepwater port and significant electrical infrastructure in place. It’s ideally suited. So, we see a future for Moneypoint. It’s just a different future. And that formed the basis of the decision we made last year to transform the station to a green energy hub.”

The critical first step, however, is the installation of a synchronous condenser to allow the station to continue to provide the necessary grid stability once its coal-fired turbines are ultimately shut down. It’s the safety net in Wall’s tightrope analogy and supplies the same kind of rotating mass, inertia and short-circuit power as a coal or gas turbine as well as absorbing reactive power to regulate voltage.

“Wind turbines aren’t connected directly to the grid in the same manner that a steam or gas turbine is,” says Nick O’Mahony, Managing Director at Siemens Energy Ireland. “This means that it’s more difficult to keep the grid frequency within its normal range of variation. So, in simple terms, a lack of inertia on the grid impacts the grid frequency. If frequency goes out of control, one part of the system must go down, and this in turn causes severe strain on the rest of the network which can result in blackouts. Currently, Ireland’s grid gets its inertia from conventional plants. The synchronous condenser provides a low-carbon alternative which will be incredibly beneficial to the Irish grid at times of high renewables.”

The synchronous condenser already installed and in its final stage of commissioning at Moneypoint includes the world’s largest flywheel and is likely the first of a half a dozen or so condensers needed for Ireland to reach its climate goals.

“By adding the flywheel,” says O’Mahony, “we’ve increased the inertia capability of the synchronous condenser solution at Moneypoint. In effect, the more inertia that can be provided in this manner to the grid, the more renewables can be connected. This in turn means less CO₂ resulting in less damage to our planet – and it does this using only a fraction of the energy required when using a conventional plant.”

“Together, the flywheel and the synchronous condenser have an inertia of 4,000 megawatt-seconds,” says Wall. “So, what’s that in reality? It’s a flywheel that weighs over 130 tons and a synchronous condenser with a rotor that weighs over 66 tons – a huge weight spinning at 3,000 rpm, acting as a stabilizer and allowing us to connect more wind power to the grid.”

The logistics behind the delivery and installation of anything as heavy as a condenser and flywheel are obviously complex. “The synchronous condenser was built in Erfurt and the flywheel in Mülheim, Germany,” says Alan Cronin, Operations Director with Siemens Energy Ireland. “The rotor forging was manufactured in Italy and shipped to Germany for finishing. But because it exceeded local legal transport weight by rail, it was only allowed to be transported on Sundays until it could reach a ferry port in Switzerland.”

The flywheel was shipped by barge from Mülheim and the condenser machine by road and barge from Erfurt to Rotterdam. “All in all,” says Cronin, “this took about two weeks, and then they were transported together by ship to a port in Foynes, Ireland, transferred to a flattop barge and towed to the Moneypoint Power Station.”

"Offloading at the jetty here is heavily dependent on the tide and weather,” says Tim Riordan, “which meant that we had a very short window to build up the ‘mattress’ at the jetty for the barge to rest on and for the offloading process.”

Riordan, a local who lives on the other side of the Shannon, has years of experience building power plants for Siemens Energy around the world, and as the on-site Project Manager he’s responsible for the synchronous condenser’s overall delivery and installation. “Usually, it takes around five months to commission a synchronous condenser,” he says, “but this project called for a reduced installation. Really only a company with the know-how and experience of Siemens Energy could deliver this successfully.”

Riordan’s counterpart at ESB, Project Manager Mark Scully, agrees: “We went with Siemens Energy because of their proven track record in delivering grid stability solutions and their ability to meet very challenging project timelines.”

It’s early September. The heat wave that caused havoc across Europe has finally broken and clouds have rolled in. More heat waves can be expected in Ireland if climate change goes unchecked – more heat waves, more storms, coastal erosion, river and coastal flooding, water stress on crops, rising sea temperatures.

Nick O’Mahony and I walk above the cliffs along Ireland’s spectacular coastal route dubbed the Wild Atlantic Way. The wind here is so strong the birds soar in place and the long grass atop the cliffs looks combed flat.

“Here on the west coast,” O’Mahony says, “we have more days when the wind blows than anywhere else in Europe.”

Just how much energy is that? Jim Dollard, during our conversation, had offered a number: “Some reports talk about 50 to 60 gigawatts off the west coast of Ireland. Others suggest 120 gigawatts. The national peak in Ireland is 7 gigawatts. So, even at the lowest wind power forecasts, 50 or 60 gigawatts is a vast quantity and provides Ireland with the opportunity to develop energy independence.”

Once the condenser is commissioned, the second step in ESB’s Green Atlantic @ Moneypoint project is the development of an onshore hub to build 1.5 gigawatts of offshore wind farms that can harness the wind, making what’s now the station’s coal yard a site where the company can assemble and launch floating wind turbines.

At this point, Green Atlantic @ Moneypoint will have brought enough wind power into the grid to provide electricity for more than half of all the homes in Ireland, but ESB plans to take their vision a step further.

The final step in the project, set for the next decade, is the development of an electrolyzer plant that will convert wind energy into carbon-free green hydrogen. That hydrogen can then be stored for long periods of time, transported by truck, ship or pipeline, and burned in hydrogen-capable turbines to generate electricity.

“Converting that wind into green hydrogen could move Ireland to energy independence in a reasonable time frame,” says Dollard. “We’ve already identified three sites along the coast of Ireland as areas for the development of green hydrogen storage capability off the Irish coast. Ireland could have significant large-scale storage, assuring a security of supply and even allowing the country to become a net exporter of energy.”

Ireland, of course, is not the only country that has high wind energy capacities. China, the USA, India, even Germany and Spain could all potentially make great strides over the next decades with a similar combination of synchronous condensers, renewable integration and electrolyzer plants. In the meantime, the project is making the Moneypoint Power Station once again a cornerstone of Ireland’s electricity.

“This is just the first of several investments we’re making in the Shannon Estuary,” says Sean Hegarty, the former Plant Manager at Moneypoint and now ESB’s Flexible Technology, Storage and Regeneration Manager. “The program and development we’re talking about will create thousands of jobs during construction and result in hundreds of high-quality permanent ‘green’ jobs for the local area.”

Hegarty has come down from Ennis for the day. People call out to him and shake his hand when he walks around the station, even though it’s nearly impossible to tell anyone apart in their helmets, safety glasses and bright yellow jackets. As we pass the condenser on our way to have a look at the river, he says: “Can you believe a few months ago we were still mowing the lawn on this spot? We’ve reimagined Moneypoint, but it’s a continuation of the service that this site has provided the country for nearly 40 years.”

While we’re watching the Shannon and the wind turbines on the far shore, Hegarty reminds me that almost 100 years ago the development of the Shannon Hydroelectric Scheme at Ardnacrusha (a village only an hour’s drive away from here) became the catalyst for Ireland’s social, economic, and industrial development.

“At the time, Ardnacrusha was the largest hydroelectric scheme in the world – eventually superseded by the Hoover dam. It was engineering on a grand scale, and it set the scene for a lot of other equally bold and ambitious projects delivered by ESB. The young engineer who came up with the idea, a guy called Thomas McLaughlin, was the first Managing Director of ESB – and he got the idea from working at Siemens Energy in Berlin!”

That night I read up on McLaughlin, and the story became even more interesting. The Irish free state was established in 1922 after seceding from the United Kingdom and ending a three-year war for independence. McLaughlin would have been around 26 years old at the time, a young man who even in his own words said, “No sincere student could have lived through that whole period of intense national enthusiasm without feeling a passionate desire to do all in his power to assist in national reconstruction.”

All the experience McLaughlin gained in Germany and with Siemens was turned toward how he could help the development of his country. “Everything I saw abroad, everything I read of, brought just one thing to my mind – can this development be applied at home? Could we have this in Ireland?”

Today, almost a full century later, with the implementation of the synchronous condenser as the first step in a grander scheme to bring clean offshore wind energy to the nation, surely there are young engineers around the world who will see Ireland as a leading light in the energy transition. And they will be asking themselves, how this development can be applied at home.