Since Russia’s full-scale invasion in February 2022, Ukraine’s energy system has been targeted by Russian attacks, resulting in rolling blackouts and limited electricity supply to some regions for a few hours a day. Ukraine has also attacked the energy infrastructure in Russia.

This summer, when electricity demand is usually lower than winter, Ukraine's generation capacity fell by more than 2 GW below peak demand of 12 GW, the IEA said.

This winter, peak electricity demand could increase to 18.5 GW. Even when the country’s nuclear plants return from maintenance outages, with electricity imports of 1.7 GW from European neighboring countries, Ukraine’s supply deficit could reach 6 GW, the equivalent of peak annual demand in Denmark.

“Further attacks on infrastructure, unforeseen equipment failures and missed maintenance cycles add further risks,” the report said.

Under current circumstances, Ukraine could meet its gas demand needs from domestic production and storage, but a colder-than-average winter would increase the need for imports.

A gas supply transit deal with Russia’s Gazprom is due to expire at the end of this year, and Ukraine has said it does not wish to extend it. Additional gas supply would have to come from flows to Ukraine from central and eastern Europe.

Another risk is the disruption to the gas and electricity supply in neighboring Moldova. Although Moldova no longer relies directly on Russian gas to meet demand on the territory it controls, it receives around two-thirds of its electricity from a power plant in the breakaway, Russian-backed region of Transnistria.

Transmission capacity with continental Europe is shared between Ukraine and Moldova. If there are shortages in Moldova, the two countries need to agree to the distribution of imports from other countries, the report said.

To help Ukraine’s energy security this winter, the IEA said that repair and construction work must be done to protect assets against further attacks, especially at network substations near nuclear plants.

Domestic energy-saving measures, the delivery of smaller combined heat and power units to the hardest-hit areas, and improved transmission of electricity imports were needed.

Ukraine will also need around 0.6 billion cubic meters of gas imports in September and October to reach its gas storage target before November.