HEAT-Analysis View code
Illustrative view of transmission lines crossing a dry landscape during intense summer heat

Heatwave-induced capacity bottlenecks in European electricity grids

HEAT-Analysis brings together three ways that extreme heat can affect a power grid: rising electricity use, changing power-plant output and hotter transmission lines. The combined model shows when these pressures may make electricity harder to deliver.

The study estimates near-term stress in grid models built from public data, rather than predicting outages in individual countries.

Enming Liang · Minghua Chen · Srinivasan Keshav

AI-generated editorial illustration, shown for context rather than as a record of an outage.

Why this matters

Europe is entering a hotter operating environment

Europe's recent climate record shows that severe heat is becoming a more important condition for infrastructure planning. Its consequences are already visible in environmental and public-health indicators.

More than 2×

Europe's warming rate

Since the 1980s, Europe has warmed at more than twice the global average rate.

WMO climate assessment
20%

A continent-wide heat-stress day

On 17 July 2024, one fifth of European land reached at least strong heat stress.

Copernicus ESOTC 2024
About 61,700

Human consequences

A peer-reviewed study estimated this toll across 35 European countries in summer 2022.

Nature Medicine study

Together, these trends raise an important question for electricity systems: how does grid operation change when heat simultaneously raises demand, shifts generation and reduces transmission capacity?

The problem

Why heat needs a whole-system view

These three effects interact through the network. Considering them together reveals how a constraint in one part of the system can change the ability of the whole grid to deliver power.

01

Cooling demand grows

More air conditioning increases the amount of electricity that must reach homes and businesses.

02

Available generation changes

Some thermal power plants lose available output as the air warms, while wind and solar production respond to the accompanying weather.

03

Line capacity responds to weather

Air temperature, sunshine and wind alter conductor heating and therefore the current that a route can carry within the modelled temperature limit.

The framework

Turning weather fields into a grid stress test

For every projected heatwave hour, the framework translates weather conditions into electricity demand, available generation and conductor temperatures. It then tests how the represented grid can serve demand within its modelled operating limits.

Research framework linking heatwaves to demand, generation, transmission thermal limits, storage and power-flow analysis
Framework panel a linking heatwaves to demand, generation, transmission thermal limits, storage and power grids Framework panel b showing the two-update temperature-dependent optimal power-flow analysis
The European analysis uses two exchanges between power flow and line temperature. Compared with a calculation continued until the results stabilise, this faster treatment gives average errors below 1% for both load-shedding and line-temperature metrics.

Method in brief

From extreme weather to network response

  1. 1

    Construct future heatwave weather

    The hourly patterns of selected ERA5 heat events from 2019, 2022 and 2024 are transferred to bias-corrected C3S/CORDEX climate baselines for 2026–2030 under RCP 4.5.

  2. 2

    Translate weather into grid inputs

    Each weather realisation determines electricity demand, renewable production, temperature-related generator availability and heating along individual line segments.

  3. 3

    Solve grid operation

    An alternating-current optimisation balances generation and power delivery while enforcing the represented operating and thermal limits. Any remaining shortfall appears as load shedding, showing where the system cannot fully meet demand.

What the simulations show

Heatwave stress varies across represented grids

For each of eight country-level grid representations, the analysis covers 480 projected heatwave hours. Differences in weather, network structure, generation, demand and storage lead to different operational responses.

Distributions of heatwave temperature, load shedding and available line capacity across represented European grid configurations
The distributions show how air temperature, unmet demand and transmission-line conditions vary across the eight public-data grid representations. Supporting statistics and line counts accompany the paper in the Source Data.

Different grids, different bottlenecks

The represented French, Spanish and Italian systems show higher load-shedding risk. The German and UK models, together with several northern counterparts, remain less affected under the tested conditions.

Interconnection helps unevenly

Links to neighbouring systems provide relief only when those systems retain spare power and the connecting routes can deliver it to the constrained area.

Demand growth increases stress

In the Spanish analysis, higher base demand increases load shedding. The storage comparison varies only the initial charge of the represented fleet; future storage locations and capacity could produce different outcomes.

Reproducible examples

Explore the modelling components

The repository provides worked examples for readers who want to inspect the main weather and engineering calculations separately.

Notebook 01

Heatwave generation

See how selected historical heat-event patterns are combined with future reference climate fields.

View on GitHub

Notebook 02

Demand calibration

Follow the calibration of temperature-dependent electricity demand using the Demand.ninja approach.

View on GitHub

Notebook 03

Thermal models

Inspect conductor heat-balance calculations and the temperature response assigned to different generator types.

View on GitHub

Scope and limitations

Stress signals, not outage predictions

The analysis shows where modelled near-term heatwaves place stress on grid configurations built from public data. These results are intended to support further assessment, rather than forecast load shedding in individual countries.

Future network expansion, generation investment, storage deployment and operator decisions could change the estimates. A next step would be to combine this stress test with detailed grid and cost data to compare demand response, transmission reinforcement, targeted storage and cross-border support under different climate and infrastructure pathways.