Evolution of the generation portfolio in Ireland and Northern Ireland – a historical perspective on recent developments

Northern Ireland within the historical context of 100 years of development since the passing of the Shannon Electricity Bill on 25th June 1925. While there were forty years of development prior to 1925, the Shannon scheme was a critical moment in the development of the all-island power system.

This paper builds on other historical accounts of developments of the power systems in Ireland and Northern Ireland with a particular focus on updating them for recent changes in the portfolio in last 10 years. These more recent changes have taken place in the context of a massive transformation of the power system from one powered by fossil fuels to one dominated by renewable energy. Policy developments put in place at a European level in the early 21st century to transition away from carbon intensive fuel have been a central driver for change.

The Ireland and Northern Ireland Capacity Market, a component of the all-island Single

Electricity Market arrangements has been an important driver of investment decisions in generation (and demand side) capacity since its establishment in 2018 (replacing the previous

Capacity Payment Mechanism in place since 2007). Since then, due to a combination of policy constraints, in particular that carbon intensive units are no longer eligible for capacity payments, the use of peat, coal and heavy fuel oil has all but disappeared from the fuel mix for the first time since the beginning of the electricity supplies in the late 19th century.

In concert with these changes has been the unparalleled rise of invertor-based renewable and storage resources. Investment in large scale renewable generation in Ireland has been driven by various government support schemes including most recently the Renewable Electricity

Support Scheme in Ireland. Critical to the integration of massive amounts of variable renewables are the various technologies that manage the variable nature of the resource including battery storage, demand side capacity and interconnection. Investment in these complimentary resources has been driven by the capacity market, system service arrangements and other specific schemes to promote the stability of the power system.

This paper will detail these seismic changes over recent years having regard for the rich history of the power system that have led us to this point and for the ambitious plans for the transition to net zero – a carbon emission free power system. As with all historical analyses of this nature, taking into account the long-term commitments in the Capacity Market (and also in the renewable energy support schemes for onshore and the newly developing offshore resource), the paper will conclude with some lessons from the past and how these can better inform future decisions regarding the future of the electricity systems in Ireland and Northern Ireland.