The island of Ireland has 5,585 megawatt and the Republic of Ireland has 4,309 MW of installed wind power nameplate capacity, the third highest per capita in the world. In 2020 wind turbines generated 36.3% of Ireland's electrical demand, one of the highest wind power penetrations in the world. Ireland has over 300 wind farms (nearly 400 all-island); mostly onshore, with only the 25 MW Arklow Bank Wind Park situated offshore as of 2020. This is unlike Germany and Great Britain two other European countries with high wind power penetration whose territorial waters (particularly the German Bight and waters off the coast of Scotland) are in extensive and growing use for offshore wind power. Ireland's instantaneous wind power generation fluctuates between near zero and nearly 4,500 MW due to weather, with an average capacity factor of 32.3% in 2015. Irish wind power generation is higher during winter and lower in the summer. The overall capacity factor of Irish wind farms is high compared to the global average of onshore wind farms which usually ranges around 20% but significantly lower than that of offshore wind farms which often achieve capacity factors around 50%. Ireland uses an EU industry subsidy known as the Public Service Obligation to support development of wind and other domestic power generation, currently levied at €72 per year per household. In the 2016/17 period, €308 million raised through this levy was planned to be granted to supporting domestic renewable energy schemes. For comparison €120.90 million was planned to be granted to (non renewable) peat generation. Concerns over energy security (Ireland lacks significant onshore fossil fuel resources other than peat, and has extensive wind resources), climate change mitigation policies, and compliance with EU Directives for market liberalisation, have all shaped wind power development in Ireland Capacity Growth Eddie O’Connor, then CEO of the semi-state owned peat harvesting company, Bord na Móna, commissioned the country's first "commercial wind farm" in a cutaway peat bog in County Mayo in 1992. Following the first commercial wind farm, wind power deployment in the Republic of Ireland started slowly in the 1990s, but increased more rapidly from the 2000s onwards. Whilst annual wind capacity growth has been variable, it has shown an increasing trend (Figure 1). Wind power has provided a steadily increasing share of electricity, from 4% (1,874 GWh) in 2005, to 28% in 2018 (10,195 GWh) (Figure 2). In the first two