Combining Wind and Pumped Hydro Energy Storage for Renewable Energy Generation in Ireland

Ireland has one of the highest wind energy potentials in Europe. The intermittent nature of wind makes this renewable resource impractical as a sole source of energy. Combining wind energy with pumped hydro energy storage (PHES) can overcome this intermittency, consuming energy during low-demand periods and supplying energy for periods of high demand. Currently Ireland has a number of hydroelectric power plants and wind farms of various scales in operation. A feasibility study was conducted to investigate the potential of securing a reliable source of renewable energy by increasing the penetration of hydroelectric power by means of combined wind-PHES developments. The greatest wind potential is experienced along the western coast of Ireland and a number of sites were identified here which satisfied a minimum mean wind speed criterion of 10.5 ms？1. Each site was then further evaluated according to topographical requirements for PHES. All but two of the identified sites are immediately unsuitable due to the presence of areas protected under European legislation; this highlights the nonenergy related obstacles in the path of renewable energy generation in Ireland and suggests that a compromise should be researched which could facilitate both renewable energy generation and species and habitat protection in Europe. 1. Introduction The negative implications of fossil fuel-based energy systems are well known and efforts to secure an alternative, renewable, and sustainable source of energy have increased in recent decades. Which alternative form of energy is the most suitable for a specified location depends primarily on the location itself: sunlight exposure, wind potential, agrosuitability for biomass cultivation, and so forth each determine the applicability of a particular energy source to a particular location. Ireland is committed to an overall target of 16% renewable energy penetration for electricity, heating, and transport by 2020 under the EU Renewable Energy Directive (2009/28/EC). Located on the eastern fringe of the Atlantic Ocean, Ireland experiences some of the highest wind energy potential in Europe (Figure 1). Wind energy accounted for 7.5% of the total electricity generation in Ireland in 2012 [1]. One of the most significant characteristics of wind energy and one of the main obstacles to achieving the renewable energy targets set out by Directive 2009/28/EC is its intermittency. This is highlighted in the 8.4% reduction of the contribution of wind energy to electricity generation in Ireland due to a lower wind potential compared to the