Gas turbines begin providing grid inertia service

Triton Power’s Deeside combined-cycle gas turbine power plant has begun providing inertia to the power grid under a six-year contract for a new stability service.

National Grid Electricity System Operator (ESO) said it is the first time anywhere in the world that a gas turbine power station has been converted to provide inertia separately from generation.

Inertia refers to the resistance of the power grid to sudden changes in frequency and has traditionally been provided by synchronous coal and gas generators with turbines spinning in harmony with the frequency of the electricity system. When there is a drop in frequency, kinetic energy stored in the turbines is absorbed by the power grid, arresting its fall.

As these plants close and asynchronous renewables become more prevalent, the ESO has begun procuring inertia separately from generation as part of a new stability service that also includes reactive power and short-circuit level contribution.

The ESO awarded contracts worth £328 million to seven sites, including Deeside, in its first trial tender in January 2020. The power station in Flintshire, which features two gas turbines and a steam turbine, had been mothballed since March 2018.

In March 2020, Triton Power began converting the two gas turbines to provide the service by installing new specialist turbine blocks. This allowed the turbines to effectively be operated as synchronous flywheels, with a small amount of power from grid being used to spin the rotors.

Mick Farr, chief executive of Triton Power, said: “The conversion of an aging traditional fossil fuelled power plant to provide grid stability services is what the energy transition is all about. It is so satisfying to see the same assets reused in a way that enables the transition and can be considered recycling in its purest form.

“Our team have worked tirelessly along with key engineering partners to make this innovative solution work in a way that provides the maximum value to the grid operator.

“I am sure we will see more of this approach as businesses react to the net zero targets but further clear policies with underpinning support mechanisms will be needed to deliver this goal across the sector.”

ESO head of networks Julian Leslie said: “Seeing Triton Power’s transformation of Deeside Power Station – from burning gas, to just providing stability services to the grid – is incredibly exciting.

“Innovations such as this, part of our new approach to system stability, are cheaper and greener than the alternative, reducing emissions and saving money for electricity consumers.

“Our stability pathfinder – creating a market for inertia and other stability services – is the first of its kind anywhere in the world and is a huge step forward in our ambition to be able to operate the GB electricity system carbon free by 2025.”

The Cruachan pumped hydro plant in Scotland became the first facility to begin providing the new stability service in July 2020. The ESO launched its second tender for the service the month before.