Ireland stopped capping wind and started buying flexibility — 50% to 75%

Ireland is a small island grid with world-class wind and few interconnections. By 2011 the system operators, EirGrid and SONI, faced a hard ceiling: the limit on System Non-Synchronous Penetration (SNSP) — wind and interconnector imports as a share of demand — stood at 50%, because stability, inertia and ramping all came implicitly from large synchronous generators. The DS3 programme launched that year set out to move the ceiling to 75%.

The trick was to stop treating stability as a side effect of fossil generation and start treating it as products. A December 2014 decision by the regulators in both jurisdictions endorsed the approach: the annual System Services budget cap rose from €60m to €235m, service products doubled from seven to fourteen, and procurement moved to a hybrid of regulated tariffs and competitive auction. Twelve services were ultimately procured under Regulated Arrangements effective 1 May 2018, and grid codes changed too, including a RoCoF withstand standard of 1 Hz/s over 500 ms.

The ceiling moved exactly as designed: by 2018, instantaneous renewable penetration had risen from 50% to 65% — described by EirGrid as a world first — then to 70% in 2021, and the 75% goal was reached in March 2022, ten years after the programme launched. Renewable energy supplied 43% of Ireland's electricity in 2020, beating the 40% target, and work has since turned to pushing the limit toward 95%.

Buy the physics you used to get for free

Defining inertia, fast frequency response and ramping as purchasable services let batteries, thermal units and other providers compete on capability rather than fuel type.

Performance-based payments and testing tied revenue to delivered capability, so the capability the grid needed was actually contracted and verified.

A hybrid of regulated tariffs and auctions kept essential services supplied while letting competition drive the price down over successive procurement gates.

Raising the SNSP limit removed curtailment risk for every wind farm investor, so the mechanism paid for itself in renewable build-out.

When a free input becomes the constraint, don't ration its complement — define the input as a product and create a market for it. Capability, not fuel type, earns the revenue.

The 75% SNSP goal was reached in March 2022 and the programme has become the international reference for operating grids with extreme renewable shares. Procurement continues through successive gates, and EirGrid and SONI have since set their sights on 95%, with market redesign work carried forward under the Shaping Our Electricity Future programme.