Wood was the first renewable resource used in Ireland for cooking, heating, and metal manufacturing. Forests came back in Ireland after the previous Ice Age, and its wood was later utilized to manufacture charcoal, a critical energy source for smelting iron ore.

One of the early applications of hydro power was the manufacturing of flour from grains. Water wheels were powered by the energy gathered in falling rivers. Windmills were employed for grain milling in locations rich in cereals but lacking in water power, such as Fingal in north Co Dublin. In Ireland, there were 250 windmills in operation by 1840.

Today, waste wood and bark from the processing of trees are used as a source of process heat in board mills and sawmills, making use of the renewable energy supplied by wood. In 2004, Grainger Sawmills in West Cork built Ireland's first combined heat and power (CHP) plant to be fueled on wood waste. Its power is fed onto the national grid.

Hydro Power

Until the large-scale development of wind energy at the end of the twentieth century, hydropower was Ireland's major contribution to renewable electricity. It contributed 2.5 percent to power output in 2014.

Wind Power

In 2006, the first REFIT program was introduced. Its goal was to more than increase renewable energy technologies' contribution to 13.2% in 2010. Ireland generated over 15% of its power from renewable sources by 2010.

Solar Power

Solar thermal energy made about 0.3 percent of Ireland's renewable energy in 1990. It supplied the primary energy equivalent of 1.2 percent of Ireland's renewable energy in 2013.

Ardnacrusha, Ireland's largest hydro-power facility, began construction in 1925. Its dam boosted the Shannon's level in order to generate enough energy to support a national system. It now supplies roughly 2% of Ireland's electricity.

At 1992, the first commercial wind farm opened in Bellacorrick, Co Mayo, ushering in the era of wind power. By 2015, renewable energy provided 23% of the state's power, with wind accounting for over 20% of it.

A state-owned enterprise produced bio-ethanol from potatoes to ease the suffering caused by oil shortages during WWII. This was an early renewable liquid biofuel that was mixed with gasoline to boost transportation fuel supply. Bioethanol is now in use and is combined with gasoline as part of the Biofuels Obligation Scheme.

The establishment of a Biofuels Obligation Scheme for road transport fuels was prompted by EU guidelines on renewable energy. Renewable energy should account for 40% of electricity, 10% of transportation energy, and 12% of heat energy by 2020, according to the national aim. Wood pellets and wood chips, as well as other wood waste, solar thermal energy, and geothermal energy, might be used to meet the latter goal.