The Electricity Supply Board (ESB; Irish: Bord Soláthair an Leictreachais), a state-owned electricity company operating in the Republic of Ireland, is established on August 11, 1927, by the fledgling Irish Free State government under the Electricity (Supply) Act 1927, to manage Ireland’s electricity supply after the successful Shannon hydroelectric scheme at Ardnacrusha and take over all existing projects for the electrification of Ireland. While historically a monopoly, the ESB now operates as a commercial semi-state concern in a “liberalised” and competitive market. It is a statutory corporation whose members are appointed by the government of Ireland.

The Shannon hydroelectric scheme at Ardnacrusha is Ireland’s first large-scale electricity plant and, at the time, it provides 80% of the total energy demands of Ireland. To give an idea of the growth in demand, the output of Ardnacrusha is now approximately two per cent of national peak demand for power.

By 1937, plans are being finalised for the construction of several more hydroelectric plants. The plans called for stations at Poulaphouca, Golden Falls, Leixlip (all in Leinster), Clady, Cliff and Cathaleen’s Fall (between Belleek and Ballyshannon in County Donegal), Carrigadrohid and Inniscarra (in County Cork). All these new plants are completed by 1949, and together harness approximately 75% of Ireland’s inland water power potential. Many of these plants are still in operation, however, as can be expected with continuing growth in demand, their combined capacity falls far short of Ireland’s modern needs.

With Ireland’s towns and cities benefiting from electricity, the new government pushes the idea of Rural Electrification. Between 1946 and 1979, the ESB connects in excess of 420,000 customers in rural Ireland. The Rural Electrification Scheme is described as “the Quiet Revolution” because of the major socio-economic change it brings about. The process is greatly helped in 1955 by the Electricity Supply Amendment Act, 1955.

In 1947, the ESB, needing ever more generation capacity, builds the North Wall station on a 7.5-acre site in Dublin‘s industrial port area on the north side of the River Liffey on the site of an old oil refinery. The original station consists of one 12.5 MW steam turbine that is originally purchased for a power station at Portarlington but instead used at North Wall. Other power stations built around this time include the peat fired stations at Portarlington, County Laois, and Allenwood, County Kildare.

Because of the risks of becoming dependent on imported fuel sources and the potential for harvesting and utilising indigenous peat, the ESB – in partnership with Bord na Móna – establishes those stations and ESB also builds Lanesboro power station in 1958. Located in County Longford, the plant burns peat, cut by Bord na Móna in the bogs of the Irish midlands. In 1965, the Shannonbridge station, located in County Offaly, is commissioned. The two stations have been replaced by new peat-fired stations near the same locations, and peat is also used to power the independent Edenderry Power Station in County Offaly.

As in most countries, energy consumption is low at night and high during the day. Aware of the substantial waste of night-time capacity, the ESB commissions the Turlough Hill pumped-storage hydroelectric station in 1968. This station, located in County Wicklow, pumps water uphill at night with the excess energy created by other stations, and releases it downhill during the day to turn turbines. The plant can generate up to 292 MW of power but output is limited in terms of hours because of the storage capacity of the reservoir.

The 1970s bring about a continued increase in Ireland’s industrialisation and with it, a greater demand for energy. This new demand is to be met by the construction of the country’s two largest power stations – Poolbeg Generating Station in 1971 and Moneypoint Power Station in 1979. The latter, in County Clare, remains Ireland’s only coal-burning plant and can produce 915 MW, just shy of the 1015 MW capacity of Poolbeg. In 2002 and 2003, new independent stations, Huntstown Power (north Dublin) and Dublin Bay Power (Ringsend, Dublin), are constructed.

In 1991, the ESB establishes the ESB Archive to store historical documents relating to the company and its impact on Irish life.

On September 8, 2003, two of the last remaining places in Ireland unconnected to the national grid – Turbot Island and Inishturk island (off the coast of County Galway)- are finally connected to the main supply. Some islands are still powered by small diesel-run power stations.

Sixty wind farms are currently connected to the power system and have the capacity to generate 590 MW of power, depending on wind conditions. These wind farms are mainly owned by independent companies and landowners.

On March 16, 2005, the ESB announces that it is to sell its ShopElectric (ESB Retail) chain of shops, with the exception of the Dublin Fleet Street and Cork Academy Street outlets, to Bank of Scotland (Ireland), converting them into main street banks. Existing staff are offered positions as bank tellers.

On March 27, 2008, the ESB announces a €22bn capital investment programme in renewable energy technology, with the aim to halve its carbon emissions within 12 years and achieve carbon net-zero by 2035.