Intensified attacks since spring 2024 have left Ukraine’s energy infrastructure in a very fragile state for the coming winter. Russia’s strategy has focused on generation and transmission assets and has used combinations of missiles and drones to evade Ukraine's air defences. As a result, Ukraine has sustained more widespread and lasting damage to its energy infrastructure compared with the attacks in earlier stages of the war, even with ongoing support for repairs from donors.

Energy supply has already been challenging over the summer months for many Ukrainians, but the full effects of the infrastructure losses have been masked by the warm weather and longer days. Diesel generators have allowed shops and restaurants to stay open, with many facilities using outdoor spaces to help with the effects of rolling blackouts.

However, once temperatures begin to fall and the heating season officially begins in October, it will become much more difficult to live and work with limited access to electricity and heat. Home to roughly 70% of the population, Ukraine's urban centres are particularly vulnerable to unreliable electricity supply, given the strong concentration of high-rise buildings that need electricity for elevators and water pumps.

The winter season can last for up to six months, with the coldest months between December to March, when temperatures can drop as low as -20 °C, and average between -4.8 °C and 2 °C. All regions, or oblasts, in Ukraine experience days with temperatures below -10 °C during the standard heating season. In the current context, this would result in huge risks for people across the country. A period of extreme cold over the coming winter would take a massive toll on the overall population and put enormous pressure on the already overstretched health system. If the winter is accompanied by inadequate provision of heat or electricity, this could lead to a renewed wave of refugees moving to other parts of Ukraine and abroad, as some places in the country become simply unliveable.

Since 2022, and especially since March 2024, Ukraine’s energy infrastructure has been degraded in ways that make this winter the sternest test yet for Ukraine’s energy system. These risks are already visible and foreseeable; they can be exacerbated by continued targeting of energy infrastructure by Russia and mitigated by successful air defence, as well as a range of other national and international actions, including expedited repair and reconstruction. Some of these risks spill over to Moldova, requiring a coordinated, regional approach.

The key risks are the following:

• A growing deficit of electricity supply relative to much higher winter demand. Peak demand is expected to increase to 18.5 GW this winter (from around 12 GW in the summer). Despite the return to service of nuclear units from maintenance over the summer and an expected 1.7 GW of electricity imported from the European Union, the deficit of electricity supply could reach as much as 6 GW, an amount equivalent to Denmark’s peak demand1. Since March, rolling blackouts that have left households without electricity for hours every day have been faced with solidarity by citizens, but longer electricity cuts in the winter months will lead to enormous strains, including on centralised water supply. Repair and reconstruction work is ongoing, but it may be impossible to bring back a significant portion of the lost assets. There is also the risk that damage from new Russian attacks outpaces the speed at which infrastructure can be repaired, undermining system stability even further.
• Inability to provide district heating to major cities. Regions close to the front lines are the most vulnerable, as most attacks on heating infrastructure have occurred in these areas. The Kharkiv region has been without large-scale heat generating capacity following the destruction of the Zmiivska thermal power plant and Kharkiv CHP-5 plant in late March. Other frontline regions (particularly Chernihiv, Donetsk, Zaporizhzhia, Sumy and Mykolaiv) have also suffered severe damage to their heat generation capacities. Heat supply is at risk as well in Ukraine’s capital, Kyiv, where 98% of the population is connected to the district heating grid and three large CHP plants provide the bulk of supply during the winter months.
• Possible need for gas imports to ease strains on the gas supply balance. Ukraine’s may require additional imports during the coming heating season. While under average weather conditions Ukraine could potentially meet all its demand requirements from domestic production and storage, a colder-than-average winter could increase import requirements through the heating season, assuming that heating intensity2 remains close to last winter’s levels. A particularly cold winter – similar to the one Ukraine faced in 2016-17 – could increase gas used for space heating in households by 25% (or 1.5 bcm) compared with the 2023-24 winter season. The expected halt of Russian gas transit via Ukraine from January 2025 will mean the end of possibilities for backhaul (or virtual reverse flows) from the European Union. This means physical west-to-east gas supplies from Central and Eastern Europe will be needed to bring additional gas into Ukraine, which could raise procurement costs (due to transmission tariffs). The adequacy of supply is also subject to risks from further attacks on gas infrastructure.
• Disruption to prevailing gas and electricity supply arrangements in Moldova. The likely end of Russian gas transit across Ukraine to the region of Transnistria from January raises major questions over how the region will receive its gas and, by extension, over the availability and cost of the electricity that it provides to the rest of Moldova. Russian gas delivered to Transnistria through a longer and more circuitous route, via Türkiye and the Western Balkans, would incur additional transit charges that would push up the price of gas to Transnistria. This would be a major shock to a region that has become used to getting gas at minimum or zero cost. An adjustment towards market prices would in turn increase electricity generation costs and the price paid by Moldovans for electricity, a politically and socially sensitive issue. If electricity production from MGRES needs to be replaced with imports from Romania, some 600 to 650 MW of interconnection capacity will be needed, exceeding the current 255 MW quota for Moldova from the allowed 1.7 GW of trade capacity with continental Europe that is shared between Moldova and Ukraine3. If gas flows to Transnistria were interrupted for any reason (including non-payment), this would have immediate and damaging implications for Moldova’s electricity supply and for Transnistria’s budget, the bulk of which comes from selling electricity to Moldova. The consequences would represent an additional source of instability for the wider region.

The coming winter and the tense geopolitical context in the region could have ramifications for the energy security of other European nations. Risks include cyber-attacks and physical threats to critical energy infrastructure that may be used to supply Ukraine, requiring increased vigilance and emergency preparedness. There could also be implications for market balances and prices, although these will be determined, as ever, by multiple factors. Electricity prices in Europe have slightly moderated since the peaks of 2022, but wholesale electricity prices in Southeast Europe, in particular, remain elevated compared with pre-war levels. Most countries in Southeast Europe are highly reliant on gas for electricity generation, and over the summer months tight gas markets have combined with congested energy corridors, warm weather and low hydropower generation, resulting in notable price disparities with the rest of Europe.

This winter will also see the scheduled decoupling of the electricity systems of the Baltic states of Estonia, Latvia and Lithuania from Russia-Belarus on 7 February 2025, prior to synchronisation with continental Europe. Following synchronisation, the energy security of the Baltic states will be strongly dependent on imports from neighbouring countries Poland, Sweden and Finland. While the Baltic transmission system operators (TSOs) have deployed much of the necessary equipment to ensure stable, independent operation, the full reinforcement of interconnectors and required IT system upgrades are set to take place between 2025 to 2030. In the meantime, there will be a lack of redundancy in the single synchronous interconnection with Poland, which will be the only link between the Baltic grid and the continental Europe system until these upgrades and reinforcements are complete.