Technical notes supporting the Marshall on Policy briefings.
The proposed LNG terminal at Shannon represents a choice between fossil pathways and renewable pathways. LNG offers short‑term security but locks in long‑term fossil reliance. Renewable system modernisation offers long‑term resilience but requires investment and structural change.
Ireland must choose its path deliberately.
Ardnacrusha shows how infrastructure shapes national capability long after construction. Built a century ago, it still contributes to Ireland’s energy system. It is a reminder that decisions made today will shape Ireland’s energy future for decades.
Infrastructure is destiny.
If Ireland modernises its system, surplus renewable energy can be used to produce exportable energy carriers such as hydrogen or ammonia. This is a long‑term possibility, not an immediate policy lever. It depends on storage, transmission, flexible demand, and market design.
Export potential is a future dividend of system modernisation.
Spilled energy means Ireland has built renewable generation faster than the system built to support it. This is momentum. It is progress. It is a sign that Ireland can move quickly if policy and infrastructure catch up.
Few countries reach this point. Fewer still act on it.
Demand is no longer fixed. It can move. It can respond. Heat pumps, EVs, industry, and data centres can shift consumption to match renewable availability. Flexible demand is the missing half of Ireland’s energy system. It is how we use surplus wind instead of spilling it.
Demand is now a tool, not just a requirement.
Ireland’s energy infrastructure has grown unevenly. Wind generation expanded rapidly. Storage did not. Transmission strengthened in some regions and lagged in others. Tariffs remained tied to fossil assumptions. Flexible demand was never developed. This uneven growth creates inefficiency and waste.
Modernising infrastructure is essential to using the energy we already produce.
Ireland imports most of its energy. Fossil fuels cost the economy billions every year. They expose Ireland to geopolitical shocks and price volatility. Every unit of spilled renewable energy increases fossil reliance and increases national exposure to external risk.
Reducing fossil imports is an economic and strategic priority.
Wind generation is strongest at night and during storms. Demand is lowest at night. Ireland’s tariff system was designed for fossil baseload, not wind. As a result, the system often has surplus renewable energy when households and businesses are using the least electricity.
This mismatch is structural, not behavioural.
Ireland spills an estimated five to seven and a half terawatt hours of clean electricity each year. This is roughly €600 to €800 million worth of energy. It represents 1.75 to 3 million tonnes of avoidable CO₂ because spilled wind is replaced by fossil generation.
Spilled energy is wasted climate progress and wasted national capability.
Curtailment is when renewable electricity is available but cannot be used. Wind farms are asked to reduce output because the system cannot absorb the energy. This happens when demand is low, transmission is constrained, storage is insufficient, or fossil generation cannot ramp down quickly enough.
Curtailment is not a failure of renewables. It is a sign that the system around them has not yet been modernised.