Djerdap 1 at 20 Percent as Power Use Hits Winter Levels

Summer electricity demand in Serbia has climbed to winter levels, with the Djerdap 1 hydropower plant running at only about 20 percent of its available capacity. Average Danube inflow at that stretch of the river stands at around 1,400 cubic meters per second, the lowest figure on record, while Djerdap 2 is operating at roughly 30 percent, according to data from the Electric Power Industry of Serbia (EPS).

The water level at Bezdan dropped to minus 167 centimeters on August 4, according to measurements from Serbia’s Republic Hydrometeorological Service. The previous low was minus 143 centimeters, set in 1909, which means the river now sits 24 centimeters below a mark that had stood as the floor for more than a century.

Why summer power use looks like January

Temperatures around 40 degrees have held for days, and air conditioners are running nonstop. Predrag Skobalj, deputy director for technological development at the Vinca Institute, says a threshold once reached only during the heating season has now been crossed in the middle of August.

“You can’t do without air conditioning, but it puts a strain on the grid. We’re now reaching the kind of electricity consumption we see in winter. These are enormous loads, a major shock to the power system,” Skobalj told RTS.

The difference from winter is that the winter peak is covered by full hydropower output, while this summer peak isn’t. Hydropower plants normally supply up to 30 percent of Serbia’s total electricity output, so the loss of output from the largest one falls on the rest of the system.

Who is covering the gap Djerdap left behind

All of EPS’s thermal power units are online except for two currently under overhaul. The missing volume is being bought on the market, at a level of around 10 percent. EPS General Director Dusan Zivkovic says the company is adjusting its operating regime to preserve reserves for fall and winter.

“We can’t expect a significant increase in Danube inflow in the period ahead. What we’re doing is maintaining continuous power supply, securing the volumes we need, including on the market if necessary, so we can keep our reservoirs at their current level and preserve our coal stockpiles,” Zivkovic said.

That sentence describes a cost that won’t show up on August’s electricity bill. The reservoirs being preserved now and the coal that isn’t being burned amount to deferred output, and power bought on the exchange during the peak hour of a scorching day isn’t cheap in any year.

The system is holding up, according to Skobalj.

“We see no restrictions or problems in the power supply. There’s no need for fear, but we must start building new energy capacity as soon as possible,” he says.

Drought is also a transport cost

A low Danube isn’t only a power generation problem. The river is a corridor for goods and fuel, and a shallower channel means smaller loads per vessel and higher costs per ton shipped.

The current level is comparable only to 1985 and 2003, and it’s lower now than it was then. The problem is regional: Hungary, Romania and Bulgaria are dealing with the same low water. Hungary gets about 35 percent of its electricity from the Paks nuclear plant, and output has fallen there too, forcing the country to cover part of the gap through imports.

Does Serbia have a way out of depending on the weather?

Skobalj answers that question in one word: “Nuclear plants. That’s the only way.” His argument is that drought knocks out hydropower, a cloudy, windless day knocks out solar and wind, and a nuclear plant with an adequate cooling system depends on neither.

The timeline, however, is long. The moratorium imposed in 1989 was lifted in 2024, a decision on entering the nuclear program is expected in mid 2027, and the first kilowatts would arrive, at best, around 2040. Between this August and that date lie fourteen summers that will have to be covered by existing capacity.

In the meantime, three levers are in play:

• coal reserves in the Kolubara and Kostolac basins, estimated at 20 to 30 years of output
• the Bistrica and Djerdap 3 reversible hydropower plants, designed to store energy generated from renewable sources
• building energy efficiency, an area where Serbia uses two to three times more energy than the EU average

The last item is the only one that works in both summer and winter, and the only one that doesn’t require a new power plant. Insulation, facades, and windows and doors cut both air conditioning use in August and heating use in January, and neither depends on how much water flows down the Danube.

The next date on the calendar is the decision on the nuclear program in mid 2027. Until then, every summer like this one is covered by coal and market purchases, and the cost of that arrangement depends on how long the drought lasts.