Development and Consenting

The development and consenting services account for the following costs: project management, design engineering, planning and consenting. These costs are normally reported as percentage of CAPEX and this percentage is expected to decrease proportionally as the installed power capacity increases and standard procedures are developed [28]. Percentage values range from 2% up to 12% of the CAPEX [21,29–31], and this may well be due to the fact that these cost are very project (i.e., single prototype or wave energy farm) and site-specific. From a general point of view and by taking the experience gathered in the wind energy sector [32], development and consenting can be estimated at 6% of the CAPEX.

#### Wave Energy Converter (Structure and Prime Mover)

The wave energy converter, including its structure and prime mover, has been reported many times to have the most significant impact on CAPEX. The structure cost

includes the detailed infrastructure design and supply of all components from the mooring attachment point, excluding the power take-off system. This also includes delivery to a port. Again, the costs reported in the literature are very project-specific, as they depend on the structure's main materials and volumes [21,24,25,33]. A value of 38% of the CAPEX is reasonable according to [26], where a range of 27% to 38% of the CAPEX has been found for this category.

#### Balance of Plant

The Balance of plant costs include costs related to the power take-off (PTO) system [34–36], the supply of all its constituting components and its delivery to the port. Mooring [24,25,33,37,38] and foundation [30,39] costs are also included in this cost centre together with the electrical installation necessary to render the farm grid-connected [30,33,40–44]. All in all, this cost centre has the second most significant impact on the CAPEX. From the costs gathered in [26], this cost centre can be estimated at 33% of the CAPEX.

#### Installation and Commissioning

Installation costs [21,24,33] include the installation of the WECs on site and the commissioning of these to a fully operational state, up to the point of issue of any takeover certificate. Those costs are to a great extent driven by vessel-chartering costs. Installation methods that require small and, thus, cheaper vessels lead to a lower cost, and the installation in port followed by towing can provide significant cost-reduction opportunities. According to the review of costs presented in [26], installation and commissioning costs include the costs of installing the foundation or moorings, the offshore substation, the WEC and the cables; they typically fall in the range of 8% to 17% of the CAPEX. In this particular exercise, they are estimated at 13% of the CAPEX.
