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SEM Chart of the Week



Let’s talk about flex: the flexibility dilemma

Ruth Young
Ruth Young

In this week’s SEM Chart of the Week, we consider the recent refusal of planning permission for the construction of a 208MW open cycle gas turbine (OCGT) “peaker” power plant in Co Meath.

While the project would assist in ensuring and maintaining security of supply in the region, the plant was intended to run on distillate oil so ultimately was refused planning permission due to its impact on greenhouse gas emissions.

This raises the interesting dilemma that the need for increased flexibility to accommodate the integration of renewables on the network and the drive for decarbonisation of generation don’t always go hand in hand.

I don’t think they’re going to play this on the radio

In order to achieve the government’s ambitious decarbonisation targets, the grid network must be able to accommodate 95% instantaneous penetration from non-synchronous renewable energy sources (SNSP) by 2030. This requires improvements to infrastructure and significant levels of flexibility to ensure the electricity system is stable and supply is secure.

Flexibility is the ability to respond to both expected and unexpected changes in demand and generation and can be provided in a number of ways, such as increased grid capacity, system services, interconnection, demand side management and fast acting and controllable generation such as the proposed distillate oil OCGT “peaker” plant in Meath.

Tomorrow’s Energy Scenarios (TES) System Needs Assessment, identifies future infrastructure needs which arise from changes in the usage of the grid, influenced by the scale and location of electricity consumption, generation, interconnection and storage.

EirGrid use a set of scenarios outlining three credible futures for the supply and consumption of electricity in Ireland to determine the areas of the existing grid that may need to be further developed or strengthened. These scenarios are in Figure 1.

The location of the proposed plant is in the “Dublin Mid-East” region. According to the TES assessment the need for grid development in this region is high to very high across all three scenarios due to the anticipated growth in large energy users, such as data centres and the expected growth in renewables across the country displacing conventional generation in the area. Flexible generation in the region like the proposed “peaker” could alleviate system concerns and help maintain security of supply. However, there is still the concern over the impact on greenhouse gas emissions.

Let’s talk about all the good things

Ireland’s reliance on fossil fuels to meet its generation adequacy needs will continue for the foreseeable future. However, this reliance will move to gas-fired generation as existing peat, oil and coal plants close.

The chart below (Figure 2) shows the assumed trajectory for distillate oil generation across the three TES scenarios.

Centralised Energy and Coordinated Action assume that all distillate units are closed by 2030. In the case of Centralised Energy, this peaking capacity is mainly replaced by gas-fired generation, battery storage and demand side units (DSUs). Coordinated Action assumes that battery storage and consumer-side flexibility play a large role in replacing peaking generation. Delayed Transition assumes that distillate generation continues to play a role, though is ultimately replaced.

It is true to say that fossil fuel generation will remain part of the generation mix on the road to a carbon-neutral power system. By 2030, approximately one third of the existing Combined Cycle Gas Turbine (CCGT) fleet will approach the typical expected life of such assets and may be replaced by higher numbers of OCGT installations due to their inherent flexibility. These are unsuitable for carbon capture usage and storage (CCUS), and so to decarbonise such generation capacity, the requirement will be to decarbonise the fuel itself.

Hot to trot

With electricity demand expected to grow, particularly in Dublin Mid-East region, it is evident that there is a need for increasing levels of flexibility on the system. How this is delivered however, will be determined by a combination of affordability, climate policy drivers and technical capabilities.

As this need for flexibility becomes more acute, it is a safe assumption that the that the value for providing it will increase.

We will be covering flexibility in more detail as part our Flexible Assets: Building the Investment Case training course on the 29 January in Dublin. For more details or to book this course check out our website.

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