Ukrainian president Volodymyr Zelensky has publicly thanked the country’s power workers for maintaining the electricity supply as Russia continues to target energy infrastructure ahead of the winter.

“I thank all the workers in the energy sector: our rescuers, repair crews, officials from local government, and private companies who work diligently to maintain our energy system despite all the threats,” Zelensky said in his nightly address.

Authorities have ordered rolling blackouts in many parts of the country and urged households to limit consumption as electricity infrastructure is targeted by Russian attack drones.

In a likely response to the Russian attacks on Ukrainian infrastructure, on Thursday, the head of the port city of Sevastopol in the Russian-annexed region of Crimea said a power plant just outside the city had suffered minor damage in a drone attack.

Mikhail Razvozhayev said a drone hit a transformer and sparked a fire but did not affect its overall operation and did not interrupt the electricity supply.

Annexed by Russia in 2014, Crimea – a region slightly larger than Sicily – has faced drone attacks and explosions. In a major setback for Russia, on October 8, a powerful truck bomb blew up a section of a strategic bridge linking Crimea to Russia’s mainland.

The war in Ukraine and the resulting energy crisis is likely to cause global demand for fossil fuels to peak or flatten out, according to a report released on Thursday by the Paris-based International Energy Agency, largely due to the fall in Russian exports.

“Today’s energy crisis is delivering a shock of unprecedented breadth and complexity,” the IEA said, releasing its annual report, the World Energy Outlook.

The shock to governments, the report said, was forcing advanced economies to accelerate structural changes toward renewable energy sources.

Also on Thursday, Ukrainian authorities said its forces were holding positions in the eastern Donetsk region against continued heavy Russian artillery attacks.

“That is where the craziness of the Russian command is most visible: day after day for months, they are driving people there to their death,” Zelensky said.

“Our soldiers are holding positions in these areas of the Donetsk region. Quite simply, they are heroes.”