Renewable and Sustainable Energy Reviews xxx (xxxx) xxx Please cite this article as: Patrick O’Kelly-Lynch, Renewable and Sustainable Energy Reviews, https://doi.org/10.1016/j.rser.2019.109583 1364-0321/© 2019 Elsevier Ltd. All rights reserved. Structural design implications of combining a point absorber with a wind turbine monopile for the east and west coast of Ireland Patrick O’Kelly-Lynch a, b , Cian Long a , Fiona Devoy McAuliffe b , Jimmy Murphy a, b , Vikram Pakrashi c, d, * a Department of Civil, Structural and Environmental Engineering, University College Cork, Cork, Ireland b MaREI Centre, Environmental Research Institute, Beaufort Building, University College Cork, Cork, Ireland c Dynamical Systems and Risk Laboratory, School of Mechanical and Materials Engineering, University College Dublin, Dublin, Ireland d SFI MaREI Centre, University College Dublin and the Energy Institute, University College Dublin, Ireland A R T I C L E INFO Keywords: Monopile Offshore wind turbine Point absorber Structural design Levelized cost of energy (LCOE) ABSTRACT The integration of offshore wind and wave or tidal energy devices could be an important step towards realizing the economic competitiveness of less advanced renewable energy technologies. The foundations of such inte- grated solutions require a major share of investment in these technologies. Monopile foundations are currently the market-leader for offshore wind farms. This paper reviews normative design methodologies and presents a simplifed concept to assess the structural steel design implications of incorporating a point absorber wave en- ergy device to a monopile for selected sites off the East and West coasts of Ireland. The consequent increase in steel tonnage were computed for both locations. The design analysis was validated against existing studies estimating the increase in wall thickness of monopiles due to the combination of wind and wave devices for several design scenarios. The fnancial implications of the combination were assessed considering the impact of each scenario on the Levelized Cost of Energy (LCOE). The work provides a review-driven methodology as a tool to obtain an initial design-based estimate of LCOE comparisons for similar devices and allows making robust decisions on development or choice of devices for a particular location. This approach will be attractive to both researchers and practitioners alike in marine renewable energy, providing relevant, connected and comparable information from frst principles to economic impact. 1. Introduction Exploiting renewable energy resources is a key priority on a global scale and especially for Ireland, where there are substantial resources and offshore renewable energy potential. This focus is in line with worldwide [1] and European [2] targets of clean energy production. While offshore wind farms are well established, wave energy is still in the research and development phase [3–6]. There remain technological and logistical challenges to their effective implementation for com- mercial purposes [7,8]. Combining offshore renewable energy devices [9,10] through shared structures or infrastructure can make less advanced technologies more competitive in terms of cost and effciency. Benefts could be gained in the initial capital costs involved for grid connection, as well as the operational and maintenance (O&M) costs associated with the farm [11]. Furthermore, by combining two or more devices, which convert energy from different resources, on a single platform, it may be possible to share the overall cost of the support structure. Several novel concepts have been developed recently which explore these possibilities [12–19] and this precisely was the key focus of the EU FP7 MARINA platform project [20,21]. For offshore wind, monopile foundations currently hold the maximum market share (~80%) [22]. They are viable up to water depths of 30 m, with XL monopiles holding the possibility to push this boundary past 40 m. Unlike wind energy, wave energy technologies are yet to converge to a specifc device. The point absorber (PA) has been found to be the most popular technology making up 42% of the total amount of Wave Energy Converters (WECs) being developed [23–25]. In line with this market share, this paper assesses the structural design implications of incorporating a PA wave energy device in the monopile foundation for an offshore wind turbine. While extensive simulation and experimentation can be carried out on the various designs of these * Corresponding author. Dynamical Systems and Risk Laboratory, School of Mechanical and Materials Engineering, University College Dublin, Dublin, Ireland. E-mail address: vikram.pakrashi@ucd.ie (V. Pakrashi). Contents lists available at ScienceDirect Renewable and Sustainable Energy Reviews journal homepage: http://www.elsevier.com/locate/rser https://doi.org/10.1016/j.rser.2019.109583 Received 28 September 2017; Received in revised form 21 October 2019; Accepted 8 November 2019