On 25 February 2022, Oleksandr Danyliuk woke up to see Russian soldiers. “I went to bed. The next morning I peered outside my window. It was 6.30am. There were four Russian armoured vehicles opposite my house,” he recalled. Danyliuk, an engineer with Ukraine’s largest private electricity company, DTEK, said Moscow’s invasion took him by surprise. Over the next four weeks a battle raged in his home city of Hostomel, a short drive from the capital, Kyiv. The fighting destroyed the neighbouring market. It also brought down numerous electricity cables and pylons, leaving civilians cold and in the dark. “For the first two days after the Russians left I wandered around in a daze. Then we got to work,” Danyliuk said. He and his team fixed up windows so they had somewhere to sleep. They began repairing the damage. Russian soldiers left booby traps: grenades and trip wires. In 45 days, power was restored. Then, beginning in October 2022, the Kremlin launched a wave of missile and drone attacks against Ukraine’s energy infrastructure. This led to blackouts, electricity rationing and a scramble to buy generators. Over spring and summer DTEK gradually restored energy capacity. Before 2022 this stood at 6,000MW. It fell to 3,000MW after Russia seized two of the firm’s thermal power plants – one in eastern Luhansk province – and bombed others. It is now back up to more than 4,000MW. Remarkably, DTEK has opened a new windfarm in the south of the country, boosting power by a further 114MW. Nine million Ukrainian homes that lost electricity have got it back again. In the Kyiv region alone DTEK brigades have repaired nearly 10,000km (6,000 miles) of power lines, brought down during six weeks of occupation. It seems likely, however, that Moscow will launch a second missile campaign this winter, designed to cripple Ukraine’s energy grid again. Last Wednesday Ukrenergo, the state-owned electricity transmission system operator, said “enemy shelling” damaged a thermal power plant. More strikes are expected, after a summer in which Russia targeted Ukraine’s grain export facilities. This time round however, Danyliuk, a power distribution expert with 25 years’ experience, is optimistic. “In 2022 we had to improvise. Now we are better prepared,” he said. He showed off a new electricity sub-plant, built a few hundred metres from his apartment in Hostomel, on what was last year’s frontline. It is situated on the outskirts of the city, next to a pine forest and railway line. The building resembles a roadside bomb shelter. Inside, behind thick concrete walls, is a bank of circuit breakers. They give off a low hum. Vulnerable cables have been buried underground. The mini-complex was shrapnel-proof, Danyliuk said. “Of course, if they drop a bomb precisely on the roof it will trash everything. But generally we can fix damage in two days.” Serhii Buriak, the head of the region’s electricity grid, said: “We have a lot of experience from last winter. “In the past an attack would knock out power for an entire area. Now we can switch quickly from one electricity source to another.” Did he have a generator himself? “I bought one for family camping trips. It’s better to have one than not,” he replied. According to its CEO, Maxim Timchenko, DTEK has spent $110m (£90m) preparing for another possible Russian onslaught. It has stockpiled 1m tonnes of coal – enough, given current demand, for three to five months, he explained. It has revamped power units and coordinated an action plan with the government. “We have done everything possible and sometimes impossible to be prepared,” he said. Ukraine’s ability to guarantee electricity this winter depended on its military, he acknowledged. The US, Germany, and other allies have given Kyiv modern air defence systems. But the number of anti-aircraft batteries is insufficient to shoot down every rocket and drone. “If a ballistic missile hits a transformer station there is not much we can do in the way of physical protection,” Timchenko said. Since last year Kyiv has stepped up its drone manufacturing programme. The UK and France have supplied long-range Storm Shadow missiles. The results have been effective. They include a recent attack on the naval headquarters of Russia’s Black Sea fleet in the occupied Crimean port of Sevastopol. Russia’s own electricity network might be a tempting next target. According to Moscow’s defence ministry, a Ukrainian combat drone dropped explosives last week on the Russian village of Belaya, 16 miles from the border with Ukraine. It damaged an electricity substation. The Kursk regional governor, Roman Starovoyt, said: “One of the transformers caught fire. Five settlements and a hospital were cut off from power supply. Power will be restored as soon as it is safe to do so.” Were such tactics appropriate? “I support any strategy of our ministry and defence and president,” Timchenko insisted. He continued: “Russia is a terrorist country. It has been waging an energy war against us. We saw what they did in Bucha [where Russian soldiers killed hundreds of civilians]. When they ran away they blew up everything. For weeks people had no light.” Timchenko said his firm – based in Kyiv, and with an office in London – was looking for help from international partners. In May it opened the first windfarm to be built in a war zone. The Tyligulska plant is a mere 60 miles from the southern frontline in the Mykolaiv region. It produces enough electricity to power 200,000 households. Over the past year, Ukraine has built more onshore wind turbines – 19 of them – than England. DTEK was now seeking a €400m investment to expand the facility, Timchenko said. The plan is to install an additional 64 turbines. This would make the farm the biggest supplier of green energy in eastern Europe. “Windfarms are more resilient than thermal power plants. You need 50 missiles to destroy a windfarm, as opposed to just one. There is a big difference,” Timchenko said. Last winter all of Ukraine’s thermal and hydroelectric plants were damaged. The Russians continue to occupy Zaporizhzhia nuclear power plant, which used to generate 6,000MW of electricity. So far national demand has been low, as Ukraine experiences an abnormally warm and sunny autumn. “Nobody can guarantee there won’t be blackouts this winter,” Timchenko said. “Unfortunately we are at war. We can’t predict the scale of Russian attacks. We will do everything we can so generators are not used.”