Cernavodă Outage Squeezes Five Grids

At 19:25 on Tuesday evening, Romania needed more than 8,000 MW of electricity. Its own plants were producing 5,873 MW. The missing 2,150 MW came from imports (Agerpres, Adevărul).

That was before the next problem arrived. Romania began preparing to shut Cernavodă Unit 2, its only operating nuclear reactor, which supplies roughly 700 MW. The Danube has fallen so low that the river can no longer cool the reactor safely (Argus, Economica). The question now sits across five power grids: can the region share a tight evening supply without forcing somebody into punishing prices?

Why 19:00 matters

The strain is not spread evenly across the day. Solar power covers a large share of demand while the sun is up, pushing cheaper electricity into the system. Then, between 19:00 and 23:00, air conditioning is still running but solar output has gone. Romania, Hungary, Bulgaria and neighbouring markets all need dependable generation or imports at the same time.

Romania has formally told Brussels and its neighbours that it is in an electricity crisis. The mechanism is EU Regulation 2019/941, which requires a government to alert the Commission and nearby countries when electricity supply is at risk (HotNews, Ziare). The Commission brought together its Electricity Coordination Group on 11 August and judged the system strained but stable (European Commission, Digi24). That makes blackouts less likely. It does little for the bill at peak hours.

The single market can move electricity from cheaper zones into stressed ones through market coupling, the automatic trading system that sends power across borders until the cables are full. It cannot make a missing megawatt appear.

Who sells, who buys

For the moment, Bulgaria is on the better side of the trade. Romanian and Hungarian traders have asked for 3,500–4,000 MW of Bulgarian cross-border capacity, according to ESO dispatch director Dimitar Zarchev (Mediapool). But Bulgaria has its own Danube exposure. Its Kozloduy nuclear plant depends on the same river, and energy minister Iva Petrova said it could keep running for about another week and a half at current water levels (DBR).

That gives Sofia a profitable but fragile position. Day-ahead prices have risen towards 150–170 €/MWh, up from 100–120 €/MWh a week earlier (Mediapool). The windfall lasts only as long as Bulgaria can keep exporting.

Hungary is the more exposed buyer. Paks, its main nuclear plant, ran at half power for 11 days before returning to full output. The result was evening imports averaging 218 €/MWh on 4 August. In one hour, Hungary paid 439 €/MWh for 3,522 MW of imported power (VG, Portfolio). Slovakia's energy regulator ÚRSO has warned of an "unusually tense" electricity situation across the region (STVR).

Romanian households are protected for now. The government's emergency plan would first hit large industrial users, with staged curtailment between 19:00 and 23:00 as a last resort (Agerpres). But if suppliers keep buying expensive power to cover evening peaks, those costs will eventually move into household contracts. Expert scenarios put possible day-ahead averages between 850 and 1,800 lei/MWh, with isolated evening peaks above 5,000 lei/MWh (Economica, Adevărul).

Coal, recovery money and the real trade-off

Bucharest has paired the crisis notification with a request Brussels has heard before: keep coal units Rovinari 4 and Turceni 5 open beyond their planned closure dates (HotNews). Coal is useful in a narrow evening crunch because it produces regardless of sun or wind. But Romania promised to close those units under its national recovery and resilience plan, the reform contract attached to EU recovery money.

That is the trade-off. If Romania reverses those milestones, the Commission can suspend payments (Ziare). And the Commission's conclusion that there is no short-term supply risk makes Bucharest's emergency argument harder to sustain.

The European grid can probably keep the lights on. But it is doing so through higher import bills, contingency plans for industry and a renewed argument over coal, rather than through any abundance of supply.