Since September 2020, National Grid ESO (Electricity System Operator) has issued four electricity margin notices (EMNs), warning that the buffer of electricity supply needed to keep the lights on was too small. Before then, no such warning notice had been issued in the UK for four years. As the UK continues the transition to renewable power generation and mass adoption of new technologies changes the profile of electricity demand, utilities must find new, more reliable and resilient methods of balancing demand and supply.

Today’s dynamic power industry demands flexible, efficient electricity generation — fundamentals that have been tested as the industry adapts its infrastructure to achieve ambitious renewable energy goals. System reliability remains paramount as the environmental and economic benefits of renewable generation stimulate the rapid growth of these zero carbon assets in the power generation mix.

As the UK retires fossil fuel plants and increases wind and solar generation capacity, utilities must plan and implement strategies to bridge this transition and manage contingencies that balance the intermittent nature of renewables. Foresight and flexibility are key to continuing along this path to decarbonisation.

Support Through Technology Innovation

Innovation projects such as Zero2050 South Wales, funded through the Network Innovation Allowance, seek to systematically identify, evaluate and test different paths to decarbonisation at regional levels. This is the strategic thinking that needs to be applied to the challenge of decarbonisation. By highlighting the right investment choices for partners and businesses, helping national and devolved governments make the right policy choices, and by testing methodologies for a collaborative decarbonisation model at a system level across a region, these initiatives will help systems meet decarbonisation goals whilst maintaining reliability.

Throughout this transition, as the UK aims to meet decarbonisation goals and sustain reliable generation no matter the conditions, the ESO will have to call on various technologies for dispatchable generation. Battery storage, reciprocating engines and gas turbines with black start capabilities can mitigate dips in wind and solar generation, especially in the face of unpredictable weather patterns and rising electricity demand as a result of increasing adoption of electric vehicles.

Battery energy storage will be a long-term player in the grid of the future, albeit scaling this technology remains the biggest challenge. When coupled with wind and solar generation, large-capacity batteries can store excess energy during peak solar or wind hours, dispatching when demand is high. Battery storage technologies have become more cost-effective with significant advancement in recent years, though energy storage installations have not kept pace with the closure of power plants.

Reciprocating engine generator technology is also compatible with the intermittent energy supply created by wind and solar. These reliable generators can fill the energy void quickly, often capable of black start dispatch at a low cost, achieving full load in 10 minutes or less, depending on operating conditions.

Modern gas turbines also are options to address periods of peak demand or unexpected outages. Advanced class turbine technology has seen dramatic improvement in the last decade with excellent energy efficiency and ramp rates of 10 megawatts per minute (MW/min), up to 100 MW/min, depending on generating unit capacity, operating conditions and optional technologies that can speed up ramp rates. During a severe outage, this nearly immediate dispatchable energy is essential to meeting the expected energy reliability demands of society.

Coordinating Strategy and Implementation

Whatever the technology or approach that assists the transition from fossil fuels to increased wind and solar energy, it is essential that utilities and industry come together to plan for the integration of such solutions. Reliability cannot be sacrificed along the way. For overall resiliency, the system operators should assess their critical loads and, at minimum, develop detailed plans to meet those critical loads.

The influx of recent EMNs serve as a warning to the UK policymakers on the implications of 100% carbon-free energy goals and the significant infrastructure shift that is required. Without close attention to the integrity and reliability of the grid, gaps like these will become increasingly more challenging to bridge.


Grid reliability in the UK will be aided further by digital substations based on IEC 61850 standards.

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Jonathan Chapman, CEng, MICE, MIET, is the managing director for Burns & McDonnell in the UK. He has more than 25 years’ experience leading teams in securing and delivering projects in the power, water, telecom and gas sectors. He has been instrumental in enabling businesses to deliver complex solutions for client needs, working on major utility programmes across the UK.