National Grid ESO




Regen has produced a new interactive report on behalf of National Grid Electricity System Operator which takes a detailed look at a ‘day in the life’ of a fully decarbonised electricity system by 2035.

The ‘Day in the Life 2035’ study provides a snapshot of how a net zero power system could function on a cold, calm and cloudy winter day. The report presents an hour-by-hour analysis highlighting the energy system challenges that must be addressed to ensure system resilience and maintain security of supply.

The report points to a much smarter, better integrated energy system based on renewables that avoids the use of unabated fossil-fuelled generation by drawing on the full range of flexibility solutions to meet the increased demand for electricity from electric vehicles and low carbon heating systems. The report concludes that:

  • the technical solutions needed to operate such a system, including energy storage and smart technologies that enable far more consumer participation, are available or are attainable with continued innovation;
  • bringing these solutions together will require a step-change in the level of investment, as well as the mobilisation of all parts of the energy industry and the participation of businesses and energy consumers.

The key takeaways from the report are that:

  • Facilitating energy storage, and development of low carbon dispatchable generation, is critical;
  • Enabling consumers to seamlessly participate in demand-side flexibility benefits everyone;
  • Interconnection and diversity of supply reduce generation and price volatility on calm winter days;
  • A digitalised energy system with agile markets and smart technologies underpins an efficient net zero power system;
  • This will be a major challenge, but achievable – a 2035 net zero power system can be achieved with substantial, coordinated investment in renewable generation, low carbon flexibility, network infrastructure, digitalisation and system operability;
  • The prize is a decarbonised electricity system that remains both secure and reliable, and a major milestone towards net zero economy.

Johnny Gowdy, director, Regen, commented, “Building a net zero power system that can operate without fossil fuels even during a low wind winter week will be a major challenge.

“This study shows that it can be achieved, but also highlights the scale of transformation that is needed. The prize is a decarbonised electricity system that reduces the UK’s dependence on imported oil and gas, and achieves a major milestone towards a net zero economy.”

Jonty Haynes, senior energy analyst, Regen, commented, “A common challenge for a renewables-based power system is how to keep the lights on when the wind isn’t blowing and the sun isn’t shining.

“The Day in the Life 2035 report, grounded in real weather data and system operation, illustrates how a net zero system could operate in these conditions, exploring options to meet the biggest challenges and pointing to the innovative solutions that are beginning to provide answers.”

Becky Hart, strategy manager, National Grid ESO, commented, “The Day in the Life provides insight into how the system could be operated on a cold, dark, still day in January 2035. It shows that a fully decarbonised electricity system is achievable and resilient, but requires starting the energy transition now.

“To accompany this work we have created a flexibility timeline with milestones and actions, which outlines what needs to happen when to make this flexible energy system a reality.”



  • Read the full publication here
  • For more information about this study, please contact Jonty Haynes

Stay informed

Sign up to the Regen newsletter to receive a monthly digest of our work to revolutionise the UK energy system, and industry insights.

We take care of your personal data. We will only contact you according to your preferences and will NEVER share or sell your details. See our privacy policy for more information