Climate & Energy · Tuesday, 25 August 2026

01 · Briefing · what happened

A low river switched off Hungary's nuclear plant. Solar kept the lights on.

Climate & Energy 2 min 16 sources

Record-low water on the Danube cut Hungary's Paks reactors to a tenth of their rating and left Romania's Cernavoda shut. Record solar held Hungary's grid within 3% of normal, and Europe still has to buy winter gas at a three-year high.

10%

of Paks still running

a 2-gigawatt plant, stopped by low river water [2]

drop in Hungary's total power

record solar covered almost all of the nuclear hole [1]

$22

per million BTU for winter gas

Europe's highest forward price since late 2022 [4]

25.7%

of new European cars electric

July, across 16 markets, up 13% on a year earlier [8]

At a glance

A record-low Danube cut Hungary's Paks nuclear plant to just over a tenth of its 2-gigawatt rating [2].
Record solar, up nearly 20% on last August, held Hungary's total power output within 3% of normal [1].
Romania's Cernavoda is still shut, and Bulgaria's Kozloduy, about a third of that country's power, cut back for the same reason [1][3].
Hungary sank two barges and is building a sill across the riverbed to lift the water back over the plant's intake limit [2].
European gas for October to December is priced near $22 per million BTU, the highest since late 2022 [4].
Europe's storage is below average, yet it imported the least gas by tanker of any July since 2021 [4].
Britain's system operator warned supply could fall short on cold days, and its household price cap is forecast near 1,729 pounds [6][7].
Electric cars took 25.7% of new sales across 16 European markets in July, and a record 35% in France [8].

Forces in play

Low rivers High↓

a record-low Danube shut two nuclear plants; levels are rising again [2][3]

The winter gas bill Building↑

highest forward prices since late 2022, with storage below average [4]

Solar as a backstop Building↑

up nearly 20% on a year earlier in Hungary this month [1]

Customers leaving the fuel Steady↑

electric cars now a quarter of new European sales [8]

In play Paks, Hungary — cut to a tenth of output; restarting toward full by Wednesday [2] Cernavoda, Romania — still shut; dredging and reservoir releases approved to restart it [3] European gas buyers — refusing today's price while their storage sits below average [4] Six EU finance ministers — asked for an EU-wide windfall tax on oil profits [5] California grid planners — reckon a tenth of future electric cars could give back 9 gigawatts [10]

How it unfolded

Early August a record-low Danube forces Paks down to just over 10% of its rating [2]
Aug 15 Hungary sinks two barges and starts building a sill in the riverbed [2]
Aug 21 a Lincolnshire grower calls it the toughest harvest in 65 years [14]
Aug 22 Romania approves dredging and reservoir releases to restart Cernavoda [3]
Aug 24 US ethanol blending credits fall 34 cents in a day after the EPA delays a compliance deadline [16]
Sept 18-19 EU finance ministers meet in Dublin with a windfall tax on the agenda [5]

Where this points

Watch the Danube's level as closely as the gas price. If the river holds through September, Paks and Cernavoda come back and Europe has a smaller hole to fill [2][3][4].

Full briefing

The river is part of the plant

Paks makes nearly half of Hungary’s electricity, and it cools itself with Danube water [1]. Two true numbers describe its collapse differently. Measured against July’s average output, August is down more than 80% [1]. Measured at the worst moment against the plant’s 2-gigawatt rating, it was running at just over 10% [2]. Both come from one event: a record-low river. Romania’s Cernavoda is still off, under a state of emergency that has run all month [3].

The notable part is not that drought hit a power station. It is what filled the hole. Hungarian solar output is up nearly 20% on last August, and total power output fell less than 3% below normal while the country’s largest plant was almost entirely gone [1]. Solar was bought as clean power and cheap power. Here it worked as a spare tyre.

The bill arrives on a fixed date

Gas has no such cushion. Forward prices for European delivery this October to December sit near $21.50 to $22.50 per million British thermal units, the highest since late 2022 [4]. Iran’s blockade of the Strait of Hormuz has cut Qatari shipments by more than 60% on a year earlier [4].

Europe’s storage sits well below its long-run average, yet it imported only 6.2 million tonnes of gas by tanker in July, its lowest July since 2021 [4]. Those two facts point in opposite directions and both are rational. Buyers are refusing today’s price, and they still have to fill before the cold. Asian utilities can wait, because their demand falls once the summer cooling season ends [4]. That difference decides who pays.

Six EU finance ministers now want windfall profits taxed, writing that oil is up about 25% and European diesel more than 70% since the war on Iran began in February [5].

What is walking away

Demand is not waiting politely. July electric-car registrations rose 13% across 16 European markets and reached 25.7% of new sales, a record 35% in France [8]. The battery industry has already turned: most of LG Energy’s North American factories now make grid-storage cells rather than car cells [9]. A price high enough to make this winter profitable is also high enough to lose customers permanently [4].

The rest of the ledger

The same summer is being priced elsewhere. Europe’s burnt area would rise 39% even if warming stopped at 1.8C, against about 1.4C now, and nearly triple at 3.6C [11]. Weather extremes have already cost the EU 822 billion euros since 1980, a quarter of it in the last four years, and only a quarter of those losses are insured [13]. Scientists are now openly discussing an “extreme of extremes”, a single disaster big enough to be a landmark, while noting the risk of sounding like they are exaggerating [12]. On the ground, banks, insurers and water companies are pushing farms toward drought-tolerant methods [15].

02 · Lesson · why it matters

Why a few centimetres of river switched off a power station

Nothing about the drought was sudden, but a cooling limit is a line, not a slope: above it everything works, below it almost nothing does.

How it works

A cause moves smoothly - a river falls week by week
But the rule that governs it is a line, not a slope
Above the line everything works, and nothing warns you
Cross it and the effect jumps all at once
Push back over the line and it returns just as fast

The twist

The size of the jump tells you nothing about the size of the push - which is why two sunken barges can switch a 2-gigawatt power station back on.

Where you've seen this

Benefits and tax

one pound more of income can cost far more than a pound of support

A fridge

food keeps at 4C and spoils at 8C; the dial only moved a little

River shipping

barges load normally until the depth drops an inch under their draught

Medical cutoffs

the same person is treated or sent home on either side of one number

The catch

Some lines are physics and cannot be moved. Others were written by people - and moving the written line is the cheapest fix available and sometimes the most dangerous one.

Full lesson

The fall that was not proportional

The Danube did not drop by 90% this month. It dropped by some centimetres, over weeks, in a way anyone watching could have described in advance. Hungary’s Paks plant dropped by close to 90%, in a matter of days.

That mismatch is the whole story. The cause moved smoothly. The effect moved in one step.

It happened because a nuclear station does not draw water in proportion to how much river there is. It needs a minimum depth at its intake to cool itself safely. Above that depth, the plant runs at full power and the river is invisible. Below it, the plant is a very expensive building. There is no setting in between.

What a line does that a slope does not

Most of our intuition runs on slopes. A bit less of the input, a bit less of the output. Prices, wages, rain, effort - we expect the world to answer roughly in proportion to what we put in.

Lines behave differently, and they behave differently in two ways that matter.

The first is that a line gives no warning. Every week before the crossing looks exactly like every other week: full output, no problem, nothing to report. The system is not degrading slowly and telling you. It is fine, fine, fine, and then it is not. Watching the output teaches you nothing, because output is the thing that hides the approach.

The second is that the size of the jump tells you nothing about the size of the push. A 90% collapse feels like it must have been caused by something enormous. It was caused by a river being a little lower than a number written in a licence.

The good news is hidden in the same fact

This cuts both ways, and that is the part worth carrying.

Hungary sank two barges near the plant and began building a sill - a low dam laid across the riverbed - to hold the water up. Romania approved dredging, a groyne to steer the flow toward its intake, and five days of reservoir releases upstream. These sound absurd next to a continental drought. They are not trying to end the drought. They are trying to move a few centimetres.

Because the rule is a line, a few centimetres is all the job requires. A 2-gigawatt plant went dark over a small distance, so a small distance can switch it back on. Paks restarted a reactor on Saturday and expects to be at full output within days.

Who else lives on a line

Once you look for the shape, it is everywhere, and it is usually where things feel unfair.

A pound more of income, and a family loses a benefit worth far more than a pound. A blood test lands a fraction above a cutoff, and the same person is treated instead of sent home. A fridge at 4 degrees keeps food and at 8 degrees spoils it. A barge loads normally right up until the channel is an inch shallower than its hull.

In each case someone will say the outcome was disproportionate. It was. That is not a fault in the system; it is what the system is made of. A rule has to be written somewhere, and wherever it is written, the two sides of it are very different places.

The lines nobody had to draw, and the ones somebody did

Here is where it gets uncomfortable.

Some of these lines are physics. Water boils at one temperature. Ice melts at another. Nobody chose them and nobody can move them.

Others were written by people. A minimum intake depth, a maximum discharge temperature, an income threshold, a pass mark. Those can be moved, and when a crossing gets expensive enough, moving them becomes the cheapest available fix. It is also the least visible one. A regulator raises a limit, and the plant that was unsafe on Tuesday is safe on Wednesday. Nothing about the water changed.

Sometimes that is sensible margin being spent as it was designed to be. Sometimes it is the margin being quietly deleted. From outside, and often from inside, the two look identical.

Which is the honest place to end. Think of who sits downstream of a line. The household on the price cap. The grower whose field crossed from dry to failed. The country whose reactor stands in a shrinking river. Each is living inside a decision about where that line goes. It was made by someone who did not know their name, and who may not have known they were deciding.

03 · Lab · your turn

The Intake Limit

Spend on the river before the plant ever falters, and feel why a fix that arrives one week late costs a whole week.

04 · Hope · carry this

Nobody bought Hungary's solar farms as a backup for a nuclear plant, and this month that is exactly what they were. Some of what we build for one reason turns out to hold us up for another.