EirGrid is consulting until 24 November 2025 on a procurement mechanism for Long Duration Energy Storage (“LDES”) of continuous electricity import and export capability of at least four hours.

Action 6 of Ireland’s 2024 Electricity Storage Policy Framework called for immediate procurement of up to 500 MW of LDES, with potential subsequent procurements of up to 500MW.

EirGrid proposes to define the service to be procured as the ability to import, store and export electricity to the transmission system at times deemed suitable by the TSO to minimise re-dispatch.

EirGrid proposes to hold an initial procurement round in 2027 for 201 MW MEC/MIC rated capacity (minimum 804 MWh duration), with a target go-live date in 2030.

How will the procurement be designed?

Asset owners that have met eligibility criteria would be entitled to bid in successive competitions to receive an LDES contract.

Eligibility criteria relate to financial turnover, previous experience, connection offer, and technical requirements.

In a tender phase, assets would bid a revenue floor price (under a cap to be set) for which a maximum of 50% of marks would be available. The other marks would be for connection methods that makes optimal use of existing grid infrastructure, and for locating in constrained areas (based on ECP analysis). The tender phase would also include pass/fail criteria, such as grant of planning permission.

What is the proposed payment mechanism?

Entities with LDES contracts would be paid based on a combination of:

• their bid revenue floor price, and
• 70% of their market revenues above their floor price, with EirGrid retaining 30%. It is anticipated that LDES assets will participate in the wholesale electricity day ahead, intraday, and balancing markets (with the scheduling and dispatch solution for battery units due to go live on 11 November 2025); the capacity remuneration mechanism; and future arrangements for system services (which will include a day ahead system services auction for reserve services). EirGrid indicates that open book accounting will be mandatory to give it visibility of revenue streams.

EirGrid would issue operational envelopes to contracted LDES assets before day ahead gate closure (and potentially closer to real time). These envelopes would inform LDES assets of import and export windows in which they are expected to trade and submit Physical Notifications (“PNs”).

Entities with LDES contracts would only get their floor price in trading periods where their PNs at balancing market gate closure are within their operational envelopes. Where an asset’s PN indicates that it will breach the operational envelope limits, it will be liable to pay a non-compliance charge. The revenue floor will not cover capacity market non-compliance charges if the asset has not indicated its unavailability due to operational envelope restrictions.

Contract length

It is proposed that the contract term will be for ten years, with early delivery of assets potentially extending contract length.

Less than four hours’ capability

EirGrid intends to separately facilitate assets that cannot meet the minimum four-hour criteria. This is to be developed in a Demand Side Implementation Plan under the National Energy Demand Strategy.

Next steps

The intent to provide revenue certainty and revenue stacking is welcome albeit that further detail needs to be developed. EirGrid plans in:

• Q1 2026 to publish a recommendation on this consultation to inform a CRU decision,
• Q2 2026 to publish a second consultation on detailed contractual arrangements, technical criteria and evaluation criteria,
• Q4 2026 to publish a decision on the second consultation,
• Q1 2027 to launch an LDES procurement round, and
• Q4 2027 to execute contracts.

EirGrid notes that integration of LDES into market and operational systems may necessitate changes to the scheduling and settlement processes. For the moment, the proposal includes in its scope storage assets that are co-located with generation, albeit separately metered, scheduled and dispatched. Hybrid connections where MEC is dynamically shared may be included at a later stage, depending on the outcome of the consultation we considered in our briefing: Potential Impact of Hybrid Connection Proposal on Priority Dispatch. That consultation did not have in its scope constrained or curtailed generation used to charge co-located storage, nor integrated hybrid projects (where co-located assets with a single meter bid as one unit in wholesale markets). However, development of market and system rules to support such arrangements would be a significant step forward in decarbonising and optimising the efficiency of Ireland’s energy system.