José Davila: Why flexibility matters to the future of our energy system

Delivering a clean energy system is about more than changing the sources of our energy — it requires a system that works differently. At its core, it depends on flexibility, the ability of the system to adapt to changing demand, variable weather and new patterns of energy use, while remaining affordable, secure and resilient.

Without sufficient flexibility, costs rise, options narrow and the transition becomes harder than it needs to be. With it, the system can make better use of renewables, reduce reliance on fossil fuels and respond intelligently when supply and demand don’t neatly align.

That challenge is why we’re part of Energy Systems Nexus - a cross industry innovation platform led by Energy Systems Catapult. Bringing together organisations such as E.ON, UK National Nuclear Laboratory and Amazon Web Services (AWS), the Nexus provides a space for industry to work collaboratively on the complex, interconnected challenges facing the future energy system.

Flex Mix: understanding the value of flexibility

The Nexus’s first collaborative project, Flex Mix, sets out to answer a fundamental question: how does flexibility influence the cost and operation of a future clean power system?  

In this context, flexibility refers to the ability of the energy system to balance supply and demand by changing when and how energy is generated, stored and used. It means energy flowing not just one way — from large generators to consumers — but increasingly two ways, with homes and businesses playing an active role through technologies such as solar panels, batteries, electric vehicles and smart heating systems.

At E.ON, our experience shows that when combined with energy-efficient homes, flexible solutions can give customers greater control over when and how they use energy. This not only helps bring bills down sustainably, but also reduces system costs and allows us to make better use of cleaner energy sources.

The findings are clear. Low levels of flexibility significantly increase system costs and limit the range of viable pathways to net zero. In contrast, a highly flexible system enables greater use of renewable generation, reduces reliance on fossil fuels and lowers overall costs.

The analysis shows that unlocking flexibility at scale could deliver around £125 billion in benefits between now and 2050⁽¹⁾, compared with an inflexible system. These are system-wide benefits that directly affect consumers, including through lower energy bills driven by reduced demand for costly new infrastructure investment.

This flexibility is so important as it allows the energy system to respond dynamically to change - shifting demand, storing energy and balancing supply across electricity and heat.

The Flex Mix modelling shows that higher flexibility supports:

• Increased integration of renewable generation
• Reduced use of gas, particularly during peak periods
• More effective use of energy storage, including electricity, heat and hydrogen
• Higher levels of electrification across heat and transport, without proportionate increases in system cost

And crucially, flexibility cannot be delivered by large, centralised assets alone. To achieve the levels required for net zero, flexibility must extend into distribution networks and behind the meter, drawing on technologies such as electric vehicles, heat pumps and domestic battery storage.

What this means for consumers and markets

In a highly flexible system, consumers stand to benefit directly — not just through a cleaner energy system, but through lower bills over time. By reducing peak demand and making better use of existing assets, flexibility helps limit the need for costly new infrastructure, one of the key pressures on energy bills in the years ahead.

Flexible technologies can respond automatically to system needs, shifting demand away from the most expensive periods and reducing overall system costs. Over time, these savings can be passed through to consumers, helping to keep bills lower than they would otherwise be in a less flexible system.

Flexibility also gives consumers more control over when and how they use energy, particularly as technologies such as electric vehicles, heat pumps and home batteries become more widespread. When designed well, flexible solutions can work in the background, delivering savings without adding complexity for customers.

Flex Mix reinforces a clear message: flexibility is essential to delivering a cost-effective clean energy system. Unlocking its full value will depend on coordinated action from industry, regulators and policymakers to ensure the right market conditions are in place to support investment and enable flexibility at scale.

José Davila is E.ON UK’s Director of Strategy and Sustainability. His career includes more than 25 years in energy, water and utilities, with spells in innovation consulting. José has worked in FTSE-100s and multinationals, run his own business and taken a sustainability start-up to first revenues.