Ireland’s Ardnacrusha Moment, Again: A Blueprint for Full Electrification

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In recent months I’ve been assisting with strategy for a couple of emerging European NGOs on key decarbonization acceleration approaches, and one of the key participants asked me an interesting question this morning. This piece answers the question.

The first NGO is Supergrid Europe, a Brussels-based organization which will be working to make real the vision and roadmap in Eddie O’Connor and Kevin O’Sullivan’s book Supergrid Super Solution, a book I assisted in editing and improving for the second edition. The second hasn’t quite been born yet, so I won’t name it, but that should be up soon, and it’s focused on clean, secure and affordable energy for all in Ireland, i.e. 100% electrification powered by renewables.

In context of the latter, I’ve been going deep and wide on Ireland’s energy landscape. The Sankey diagram above is one I created from Sustainable Energy Authority of Ireland (SEAI) data of Ireland’s current energy flows, more or less. They don’t publish rejected energy because in most cases it would be an approximation and in fact Irish Sankeys have excluded it for the everything except electricity, rather hiding the cancerous boil. (Fun fact: Sankey diagrams were invented by Irish engineer Matthew Henry Phineas Riall Sankey.)

You’ll note that Ireland is wasting 56% of the energy that’s coming into its economy. That’s better than the United States, which sees 66% waste, because Ireland doesn’t drive and fly nearly as much as the USA, and doesn’t live in sprawling, poorly insulated McMansions to nearly the same extent. But still, 56%? There’s got to be a better way.

Recently, O’Sullivan, Environment & Science Editor at The Irish Times when he’s not advising the NGO or struggling with getting the final version of the book into print — successful very recently — reached out to me and asked me an interesting question: what if Ireland spent the same money on a major chunk of decarbonization technology as it did 100 years ago on a big hydroelectric dam? What would I choose to spend it on?

The historical reference point was obvious. In the 1920s, the young Irish Free State made a radical choice. It took one-fifth of its national budget — roughly 20% — and spent it on the Ardnacrusha hydroelectric scheme. At the time, it was one of the largest infrastructure projects in the world, and it electrified the nation. Ardnacrusha powered 80% of the country’s electricity for years. It was transformative, not just because it lit lightbulbs, but because it showed what determined public investment could do. That same proportion of public spending today — about €24 billion over five years — could be deployed again, but what would be as transformative?

The possibilities are real, the technologies proven, and the costs increasingly manageable. For onshore wind alone, €24 billion buys around 18 gigawatts of capacity. That’s nearly four times what Ireland currently has installed. With Ireland’s strong wind resource and an average capacity factor of 30%, that would generate around 49 terawatt-hours of clean electricity every year. Given that Ireland’s total annual electricity demand today is around 31 terawatt-hours, this one investment could oversupply the current grid and allow Ireland to electrify transport and heating while exporting surplus power. Over a 25-year turbine lifespan, that’s about 400 million tonnes of CO₂ avoided, assuming it displaces mostly gas-fired electricity.

Offshore wind — either fixed or floating — costs more per megawatt but delivers higher output per unit. Fixed-bottom offshore wind farms are mature, with costs around €3.3 million per megawatt installed. With €24 billion, Ireland could install 7 gigawatts of capacity offshore, delivering roughly 29 terawatt-hours of electricity annually. Floating offshore wind, while more expensive today, is rapidly dropping in price and opens up vast resource areas farther from shore. At projected late-2020s prices, €24 billion could deploy around 8 gigawatts of floating turbines, generating up to 35 terawatt-hours annually. Either investment supports deeper electrification and enables the export of surplus power, potentially via new interconnectors to Great Britain and continental Europe.

If we shift focus to solar, rooftop systems offer a different kind of return. Ireland isn’t southern Spain, but solar still works — particularly on homes and businesses that use the power directly. At current costs, about €1,500 to €2,000 per kilowatt, €24 billion could fund solar arrays for nearly every viable roof in the country. That’s around 14 to 16 gigawatts of capacity, producing roughly 13 terawatt-hours of power per year. While the capacity factor is lower, solar complements wind nicely by producing during calm, sunny days when wind might be low. Over 25 years, this could avoid over 100 million tonnes of CO₂, especially if paired with batteries or demand-shifting appliances.

Speaking of batteries, grid-scale storage is increasingly seen as the glue that holds renewable-heavy systems together. At a cost of about €300 per kilowatt-hour for four-hour lithium-ion systems, €24 billion could buy roughly 20 gigawatts of power capacity and 80 gigawatt-hours of storage. That’s enough to meet peak national demand and to shift up to 29 terawatt-hours of electricity per year from surplus to shortage hours. If those batteries are charged with renewables, they can prevent curtailment and reduce the need for fossil-fueled peaking plants. Over a 15-year lifespan, the cumulative CO₂ avoided could be in the range of 120 to 150 million tonnes.

Pumped hydro storage offers similar grid services but with far longer durations and operational lives. Ireland’s terrain—especially the coastal valleys of the northwest — lends itself well to this technology. With €24 billion, the country could build five to six large pumped hydro stations, adding up to 9 gigawatts of power capacity and 300 gigawatt-hours or more of energy storage. That’s enough to provide backup for multiple days of low wind or high demand. Over a 40- to 50-year lifespan, these facilities could avoid 400 to 500 million tonnes of CO₂ by enabling high renewables integration and displacing gas-fired generation during shortfalls.

On the demand side, €24 billion spent on heat pumps would transform residential heating. With an average installation cost of around €12,000, that amount could fund two million retrofits, covering nearly all Irish homes heated with oil or gas. Each unit would save roughly two and a half tonnes of CO₂ annually compared to fossil boilers. Over a 15-year heat pump lifespan, that adds up to about 70 million tonnes of CO₂ avoided—more if the grid is cleaner. Alternatively, that same €24 billion could go into district heating systems, covering 1.3 to 1.5 million homes in urban areas with low-carbon heat from waste energy, geothermal, or centralised heat pumps. District systems have a longer lifespan — often 40 years — and could displace more than 5 million tonnes of CO₂ annually, totalling around 200 million tonnes avoided over their lifetime.

In transportation, €24 billion buys a full fleet transformation. At €30,000 per electric vehicle, fully subsidized, the country could replace 800,000 petrol and diesel cars outright. With partial subsidies, as many as 1.5 million could be converted. That would electrify nearly the entire personal transport sector. Assuming each vehicle saves about two tonnes of CO₂ annually, the fleet would reduce emissions by 2 to 3 million tonnes per year, or around 30 to 40 million tonnes over their lifetimes. Add in buses, delivery vans, and strategic electrification of freight corridors, and the impact rises.

But none of it works without the grid. Today’s electricity system was never designed for three times the load, let alone millions of devices pulling power and feeding it back. A foundational upgrade to Ireland’s transmission and distribution infrastructure would cost somewhere between €12 and €15 billion. That includes new high-voltage lines, dozens of upgraded substations, and thousands of kilometres of reinforced distribution feeders. Another €4 to €6 billion buys digitization — smart meters, automated controls, and real-time monitoring systems that allow the grid to operate close to its limits safely and flexibly. With this investment, the grid could support peak demands of 10 to 12 gigawatts, double current levels, and integrate 25 to 30 gigawatts of renewable capacity. That alone would avoid hundreds of millions of tonnes of emissions by enabling electrification in heating, transport, and industry.

Finally, €2 to €3 billion invested in cross-border HVDC interconnectors would connect Ireland more fully to the British and European grids. That means resilience. It means that when Ireland overproduces wind, it can export the surplus. And when there’s a shortage, it can import clean power instead of firing up fossil plants. The Celtic Interconnector to France is already under construction; a second link to Belgium or the Netherlands and a new route to Scotland could expand capacity by another 2 gigawatts. Each gigawatt of interconnection can displace about a million tonnes of CO₂ annually, depending on flow direction and marginal fuels. Over a 40-year asset life, two new links could avoid 40 to 60 million tonnes of emissions while enhancing security and price stability.

The total picture is staggering. In raw emissions terms, nearly every option outlined here results in lifetime savings in the range of 70 to 500 million tonnes of CO₂. Most cost less per tonne than carbon taxes. Some pay for themselves in energy savings. All create jobs. And critically, the grid investment — boring though it may seem — is the keystone. Without it, electrification stutters. With it, Ireland can unlock everything else.

And so to Kevin’s question. What would I suggest they spend transformative amounts of money on, if only one major project could be chosen in the footsteps of Ardnacrusha? The grid transformation. It enables everything else and isn’t going to be done with municipal or personal money. Most Irish people will happily buy rooftop solar, electric vehicles and heat pumps, but they won’t be buying a personal HVDC system. Developers who see massive export opportunities from the west coast’s astounding offshore winds will invest if curtailment is eliminated.

This isn’t a theoretical exercise. This is the scale and scope of action we need to take climate goals seriously. It’s what following through on Ardnacrusha’s legacy would look like in the twenty-first century. One dam lit the nation. €24 billion can now enable powering, heating, and moving it — cleanly, permanently, and affordably. That’s not just good economics. That’s the foundation of a livable future.