Russia has begun its winter campaign to freeze Ukraine into submission early and since the end of July has been tearing into what is left of Ukraine’s power sector.

Last year’s campaign only scaled up in September, hitting Ukraine's power grid in the hope of making its major cities unliveable. Temperatures in apartments in Kyiv dropped to below -10°C and residents slept in tents inside their living rooms to preserve what little heat they could generate. But amazingly, residents got through chilling winter to fight on. This year Russian President Vladimir Putin has started the campaign earlier, hitting the hard to. Repair ultra-high voltage substations and fuel depots as Kyiv braces for what is widely expected to be an extremely bitter winter.

According to IntelliNews calculations, Ukraine has 12 GW of generating capacity left, down from 54.5 GW before the war, according to Energy Minister Denys Shmyhal.

“Putin wants to finish off our energy system and derail our economy and weapons production,” Shmyhal told Politico. “He also hopes in winter our society will break from exhaustion, and pressure leadership to sign the surrender.”

This is the fourth winter Russia has spent trying to switch off Ukraine's lights, but Putin is scaling up the assault significantly. The strikes have started earlier and spread from electricity to fuel and water; the ultra-high-voltage nodes that hold the grid together are back in the crosshairs; and Ukraine is hitting Russian refineries in return, to markedly less effect.

An early start

Last winter the grid campaign built slowly through the autumn before Russia turned it into a weapon in the depths of January, timing its heaviest barrages to the Siberian cold and leaving half of Kyiv in subzero darkness.

This year the attacks escalated in June and July, Russian drones and missiles hit more than 200 Ukrainian petrol stations, roughly three a day, in a campaign that mirrors Ukraine's own strikes on Russian refineries. Zaporizhzhia alone counted 54 hits on filling stations in the 24 days to July 27.

The pace picked up in August. On the night of August 4-5 Russia fired 24 ballistic and four cruise missiles at Kyiv alongside 115 drones; not one missile was intercepted, and the salvo flattened a Nova Poshta sorting hub and several retail warehouses. Days later, on August 9, drones struck the Odesa combined heat and power plant and seven substations, along with Ukrnafta oil and gas facilities in Sumy region.

Bankova, Ukraine’s presidential administration, knows what is coming. Notably, in mid-July Zelenskiy handed the premiership to Serhii Koretskyi, the former Naftogaz chairman, a move read as preparation for a heavy winter bombardment, and there were several other energy professionals amongst his nominations for the new Cabinet during a surprise government reshuffle.

The map of the blackouts

Odesa has taken the worst of the opening rounds. The August 9 strikes knocked out power to 128,400 households before crews from Ukraine’s leading utility company DTEK restored it, and the port city has form: a single 750kV substation hit in December blacked it out completely for nearly two days, killing the heating, the mobile networks and the power link to Romania.

Beyond Odesa the damage is spread thin and wide. By the worst of last winter more than half of Ukraine's 27 regions were under emergency power regimes, with rolling blackouts running past eight hours. The fuel strikes have concentrated on the frontline belt — Sumy, Kharkiv, Donetsk, Dnipropetrovsk, Zaporizhzhia and Mykolaiv — where mobile refuelling points now stand in for filling stations that have been destroyed.

Shmyhal says the target list has widened again. “Last winter they targeted electricity and heating, but you could still survive if you had gas and water,” he said. “Russia's goal now is to destroy our water supplies. It is difficult to survive for more than three days without water and sewage.”

Why the 750kV nodes matter

The part of the system Ukrainian engineers fear for most is a set of around 90 ultra-high-voltage 750kV substations that form the spinal cord of the Soviet-built grid, sitting above hundreds of smaller 330kV stations. They carry power across long distances, tying the still-working nuclear and hydro plants to the cities and to neighbouring grids.

“These are not just any substations — they're the skeletal structure of the Ukrainian grid,” an adviser to grid operator Ukrenergo told IntelliNews. “They connect nuclear power plants to the rest of the country, balance regional loads, and interconnect with neighbouring countries. Take one down and you're not just blacking out a neighbourhood, you're disrupting a region.”

The 750kV level is rare in Europe, where most transmission runs at 400kV or lower, which makes the transformers hard to source; the European grid operator ENTSO-E has arranged emergency deliveries up to 2.1GW but reserves are thin. For much of the war Russia left these nodes alone. That restraint has gone: the substation linking the Rivne nuclear plant to Kyiv was struck in the last big campaign, and Odesa's was among the first hit this time.

Ukraine hits back, to less effect

Ukraine is hitting back in kind. Its long-range drones have ranged ever deeper into Russia — on August 10 it launched more than 450 at 16 regions, hitting the Taneco refinery in Tatarstan some 1,300 km away, a petrochemical plant in Tyumen beyond 2,000 km and, it said, a refinery more than 6,000 km from the border.

It is also picking apart the grid in the territory Russia occupies. Ukraine's Unmanned Systems Forces hit 240 energy facilities between July 1 and August 13, 29 of them in a single day, commander Robert Brovdi said, in strikes reported by Ukrainska Pravda that took in the Balaklava thermal power plant in Sevastopol and substations across occupied Zaporizhzhia and Donetsk oblasts, among them the 110kV nodes feeding Mariupol. Overnight on August 13-14 a drone strike also set the port of Ust-Luga in Russia's Leningrad region ablaze.

Shmyhal reckons the refinery campaign has knocked out about 40% of Russia's primary refining capacity and driven fuel shortages across dozens of regions. But it is a different kind of damage. Refineries can be patched; Russia has kept crude exports at record volumes by simply shipping more unprocessed oil abroad, softening the economic hit, and its power system is far larger and more redundant than Ukraine's.

Ukraine's defence is now as much about hardening as shooting down. Kyiv is short some €650mn ($750mn) for the winter even after a €2bn-plus international support fund, and is spending what it has on protective covers for power and water sites, modular boilers and generators, and the distributed gas units — more than 760 MW added last year — that are harder to knock out than a handful of big plants.

For now the two grids are being fought over in opposite ways. Russia is methodically taking apart the system that keeps Ukrainians warm; Ukraine is squeezing the fuel and export economy that pays for the war.