Comment by Bunmi Adefajo, Business Leader – Modelling

If we’re to achieve the flexibility needed for our transitioning energy system to thrive, and crucially, to make sure it’s affordable, infrastructure investment needs to be planned and built on the back of modelling we have confidence in. This modelling needs to take account of the latest technologies, their cost and operating assumptions, and we need methods to robustly test the simulations we create.

Keep me updated

In the run up to our annual Innovating to Net Zero conference, being held in Birmingham in February, we’ve been amending the inputs for our detailed multi-vector, whole-systems modelling that is used to underpin the event. It will allow us to highlight how flexibility technologies may operate in the future and the impact this has on the energy system.

Our Energy System Modelling Environment (ESME) tool is a peer-reviewed, whole-system model that optimises total-system cost. It is independent of sector interests, identifies cost-optimised decarbonisation pathways across the whole system, and has provided in-depth evidence for industry, government and the Climate Change Committee.

By modelling how different energy technologies might be used under a range of constraints such as emissions targets and varying deployment rates, we can simulate and explore the interactions between different parts of the energy system and how it could evolve. All while working out how to transition to a cleaner system for the lowest cost.

Building on the modelling approach adopted for our 2024 conference (summarised in this technical report), we have updated ESME to allow a better representation of how future energy designs may impact the need for flexibility. This includes:

• Developing scenarios that explore different routes to meeting the Clean Power 2030 target, including those proposed by NESO where offshore wind is estimated to range from 25 GW to 50 GW.
• Improved representation of new demand and generation technologies including data centres (ESME assumes 12.2 TWh of electricity consumption in 2030, rising to 35.9 TWh in 2050), and we’ve added the Viking interconnector.
• A general refresh to update costs for some storage technologies, the uptake rate of electric vehicle adoption and the new deployment date for Hinkley Point C.

What about flexibility?

But updates are only one important part of the puzzle of innovating to Net Zero.

One of the things excites me as the Business Leader for the Modelling Team is creating new models where we see a capability gap. Whole-system models like ESME are great for identifying the amount of generation needed to meet a specific energy demand at least cost but most can’t accurately address storage and flexibility. They can’t see how energy supply and demand changes on an hourly, or even sub-hourly basis. Or they underestimate variability in weather. That’s not great when wind patterns and cloud coverage will increasingly come to influence our energy system.

Conversely, other models address flexibility and storage volumes well, but don’t capture the whole-systems aspects, for example pure operational dispatch models.

ESME Flex was created to bridge this gap, allowing us to produce least cost, optimal pathways to Net Zero that include flexibility and storage too. Essentially, ESME builds the system, and ESME Flex attempts to operate it!

How ESME Flex works

ESME Flex takes an existing blueprint for an energy system designed by ESME and then dispatches that system on an hour-by-hour basis for a series of days and weeks to build a picture of how an energy system would operate over a period of years.

When deciding how to operate this energy system, ESME Flex works to ensure all demand is met all of the time while keeping the operational costs as low as possible. It takes account of energy demand, the availability of renewable energy, fuel costs and carbon emissions.

This allows us to explore in greater detail the role of flexibility and the technologies that provide it. And to answer questions such as “How will the future energy system continue to run during several weeks of low-wind generation?” or “How many batteries could we need by 2040?”

To help us explore into these questions at our coming Innovating to Net Zero event, we’ve made some specific updates to ESME Flex too. These include:

• More detailed representation of demand and renewable generation that is available over the peak gap periods.
• New functionality to explore the total flexibility requirements of an energy system under different weather conditions.
• Improved cost data for storage technologies.
• The rapid fall in battery prices.

Conclusion

Putting these tools together is the missing link needed to help policymakers and innovators work together to drive forward the innovations in flexibility our future energy system will need.

The Innovating to Net Zero 2026 report will be the first chance to test these tools together in earnest. We are really excited about sharing the results with you at our Innovating to Net Zero Conference and Exhibition on 25 February 2026. You can now download the report at the link below.