This article is designed to give a general understanding of the electricity generation industry in Ireland. It explains the fuel which we use, the ways in which we produce our electricity, a description of major power plants on the island and our electricity distribution system.

Types of fuel used to generate electricity

Ireland has an electricity producing capacity of approximately 6000MW. We produce about 25TWh per year which works out to be about 5.6 MWh per capita. We are one of the lowest consumers per capita of energy in Europe (Norway being the highest at just under 25MWh per capita). The fuel which Ireland uses to produce its electricity varies. There is a mixture of Coal, peat, oil, Natural gas, electricity and renewable energies. The consumption distribution ( between 1990 and 2008) of these energy sources can be seen in the graph below. As can be seen, the country relies heavily on natural gas and oil while peat consumption has remained steady since 2000. Renewable energy consumption is increasing since 2002, as is consumption of imported electricity.

{Total final energy consumption by fuel in Ireland (1990-2008) Sustainable Energy Authority Of Ireland: Energy in Ireland 1990 - 2008, 2009 report}

According to the 2008 Sustainable energy Ireland provisional energy balance report, the country imports 92.1% of the natural gas which it consumes.  It imports 100% of it’s coal and crude oil and produces 100% of its peat. These are quite important figures regarding Irelands energy industry as it can be seen that the Island relies very heavily on fossil fuel importation.

Methods of electricity production

The figure above shows that Ireland produces electricity in various ways. In 2007 9.4% of electricity was produced by renewable energy which mainly consists of wind and Hydro-electric power (HEP). The rest however is produced by fossil fuel. Most modern day power plants which consume fossil fuel run on the concept of a combined cycle gas turbine. This system basically consists of a gas turbine and a steam turbine (how many gas or steam turbines are involved depends on the particular system). Generally the exhaust gasses from the gas turbine can reach temperatures of up to approx. 500°C. This waste heat is reused to create steam which is in turn run through the steam turbine.  A modern system such as this generally reaches efficiencies of between 50% to 60%. That is 50-60% of the energy originally in the fuel is converted to electricity.

Poolebeg

The poolebeg power station consisted of various types of turbine systems. It was owned by the ESB and had an output capacity of 1020 MW. There were 6 units on the site. The three oldest turbines had the ability to fire on oil or Gas. The remaining three turbines consisted of 2 gas turbines and a steam turbine making up the combined cycle system explained above. Poolebeg went offline in 2010 as a result of plans to reduce ESB’s monopoly on electricity supply after the introduction of a liberalized market in 2007.

Moneypoint

Moneypoint was commissioned in 1985. It is located in Co. Clare and has a maximum output capacity of 915 MW. It is also owned by the ESB and is the only coal fired power station in Ireland. The plant consists of three units capable of producing approx. 305 MW each. Moneypoint underwent some renovations in previous years in order to improve overall efficiency of the plant as well as emission reduction.

The Irish Wind Energy Network

The Irish wind turbine system has a maximum output capacity of approx. 1000 MW (That is 1/6th of the total maximum output capacity in the Republic of Ireland. It is made up of various wind farms across the island the biggest of which will have a capacity of 30 MW and is planned to be situated in Co. Clare.

You can read more on the operation of wind turbines here.

Hydro-electric Power (HEP)

Ireland has two major HEP stations; Ardnacrusha (86 MW) and Turlough hill (292 MW). While there are many more located across the country, such as Erne, Clady and the Lee power station (as well as many small scale units), they are all under the 50 MW capacity mark. A HEP station has an average lifespan of approximately 90 years. Turlough hill is a Pump storage hydro power station. This means that excess electricity at low peak consumption times is used to pump water from the lower to the higher reservoir. The water in the higher reservoir is then released at high peak consumption times to the lower reservoir, passing through turbines in order to produce power.

Ardnacrusha is different to turlough hill in that it operates almost continuously. The system is comprised of three Francis turbines and a Kaplan turbine. Ardnacrusha was able to meet almost all of Ireland’s electricity demand alone in its initial days of operation in 1929 (today it only contributes to between approx 2-4% of Irish electricity production!). It was a milestone in Irish engineering history in that the country had just come out of a civil war and the station was to supply electricity to over 95% of the republic. It was a time of poverty and mass unemployment in Ireland. The project supplied around 5000 jobs but still caused unrest with the poor wages that were being offered. In 2002, the power station was presented with the International landmark and milestone engineering award by the Institute of Electrical and Electronic Engineers and the American Society of Civil Engineers.

Electricity distribution systems

The transmission system is a network of high voltage lines used for transporting bulk electricity supplies across the country. In Ireland there are over 5800 Km of high voltage lines. The system also includes high voltage transformer stations for stepping up or down the voltage for safer transportation. After these stations the electricity is further distributed locally at 10, 20 and 38 kV. Larger industrial operations take their power directly from these stations. The Irish national grid was originally designed for 110 kV transmission lines but as demand for electricity grew 220 and 400 kV lines were erected. The electricity transmission system operator (TSO) in Ireland is Eirgrid who also have the responsibility as market operator in the wholesale electricity trading system.