What happens to energy infrastructure when temperatures exceed 35°C?

Heatwaves are putting Poland’s power grid to the test. Year after year, temperatures above 35°C are becoming less exceptional in Poland.

Experts at SPIE Energy Poland point out that such periods represent a major challenge for power network operators, whose infrastructure must continue to deliver reliable electricity under conditions very different from those it was originally designed for several decades ago.

High temperatures affect the operation of the entire electricity system. The grid must work harder precisely when operating conditions become less favourable. During the hottest hours of the day, electricity demand increases significantly, driven in part by the use of air conditioning and other cooling systems. This places additional strain on infrastructure while operators must contend with the physical limitations of electrical equipment and networks. In the case of high-voltage transmission lines, elevated temperatures can further reduce transmission capacity, meaning that during periods of peak demand operators have a smaller safety margin than they would under more moderate weather conditions.

The greatest challenge, however, is not a single hot day. Far more significant are prolonged periods of high temperatures lasting several days, when every element of the power infrastructure operates under increased load for extended periods while cooling capacity remains limited. During these conditions, overhead conductors heat up, expand and sag further. At the same time, equipment at electrical substations is less able to dissipate heat naturally generated during electricity transmission.

“The energy sector is now operating under conditions that only a few decades ago would have been considered exceptional. We are increasingly seeing prolonged periods of very high temperatures lasting for several consecutive days. This requires network operators not only to manage the grid on a day-to-day basis, but also to modernise infrastructure systematically and improve its resilience to extreme weather events,” says Rafał Okoński, Commercial Director at SPIE Energy Poland.

A grid designed for a different climate

A substantial part of Poland's electricity infrastructure was built at a time when heatwaves were less frequent and shorter in duration. Naturally, networks were designed with appropriate safety margins, but the climatic conditions that are now becoming the norm were not those on which the original design was based. As a result, Poland’s energy sector now faces the challenge of adapting existing infrastructure to a new climate reality. This applies not only to transmission and distribution networks, but also to substations, control systems and technologies supporting real-time monitoring of equipment performance.

“Many of the overhead power lines currently in operation were originally designed with conductor operating temperatures of around 40–60°C in mind. Modern solutions are already engineered to operate at conductor temperatures of up to around 80°C, while ongoing infrastructure upgrades include the gradual replacement of the most heavily loaded components of the network,” explains Rafał Okoński.

High ambient temperatures reduce the ability of equipment to dissipate heat, while increased electricity demand results in higher operating loads. Transformers are particularly vulnerable, as they generate significant amounts of heat during operation and rely on transformer oil-based cooling systems. During prolonged heatwaves, heat exchange becomes less efficient, increasing the risk of overheating and making continuous performance monitoring even more important.

“Contrary to popular belief, the most likely consequence of a heatwave is not a nationwide blackout. Much more common are localised overloads, failures of individual infrastructure components or temporary disruptions to electricity supply. In situations where the system comes under particularly heavy strain, operators may also introduce measures to limit electricity consumption by the largest industrial users, potentially leading to production downtime and measurable financial losses for businesses,” adds the SPIE Energy Poland expert.

The risk increases further when heatwaves are followed by severe thunderstorms and strong winds. This is why investments by energy companies in digitalisation, automation and continuous infrastructure diagnostics are becoming increasingly important. These technologies enable operators to identify potential issues more quickly and manage the network more effectively during periods of heightened demand.

Grid resilience is becoming one of the energy sector's greatest challenges

The growing frequency of extreme weather events means that infrastructure resilience is becoming one of the key priorities for the energy industry. This includes both upgrading existing network assets and implementing new technologies that improve the ability to predict risks and respond more rapidly when problems arise.

“The biggest challenge for the energy sector is not a single day with temperatures above 35°C, but several such days in succession. Under these conditions, infrastructure operates under elevated load for prolonged periods, while the system's safety margin gradually diminishes. That is why investments aimed at strengthening grid resilience and identifying potential risks at an earlier stage are becoming increasingly important,” emphasises Rafał Okoński.

Both short-term and long-term weather forecasts indicate that Poland’s energy sector will increasingly have to operate under climatic conditions that, until recently, were regarded as exceptional. This highlights the need for continued investment in modernising infrastructure and developing systems capable of coping with increasingly demanding summer conditions while ensuring rapid response to potential disruptions.