Wave energy converters (WECs) can play a significant role in the transition towards a more renewable-based energy mix as stable and unlimited energy resources. Financial analysis of these projects requires WECs cost and WEC capital expenditure (CapEx) information. However, (i) cost information is often limited due to confidentiality and (ii) the wave energy field lacks flexible methods for cost breakdown and parameterisation, whereas they are needed for rapid and optimised WEC configuration and worldwide site pairing. This study takes advantage of the information provided by Wavepiston to compare different costing methods. The work assesses the Froude-Law-similarities-based “Similitude method” for cost-scaling and introduces the more flexible and generic “CapEx method” divided into three steps: (1) distinguishing WEC’s elements from the wave energy farm (WEF)’s; (2) defining the parameters characterising the WECs, WEFs, and site locations; and (3) estimating elements that affect WEC and WEF elements’ cost and translate them into factors using the parameters defined in step (2). After validation from Wavepiston manual estimations, the CapEx method showed that the factors could represent up to 30% of the cost. The Similitude method provided slight cost-overestimations compared to the CapEx method for low WEC up-scaling, increasing exponentially with the scaling.

This paper is a first general dissemination of the H2020 Project Wave to Energy and Water (W2EW) started in January 2019. The joint vision of the W2EW consortium (Wavepiston, Ener.Med, Fiellberg, Vryhof) is to deliver a world-beating wave powered technology solution for electricity production and desalination. It relies on the innovative integration of wave energy and sea water desalination technologies, to produce zero-emission electricity and fresh water, with dynamic optimization of energy production and maximizing the available wave energy using fresh water as storage. The W2EW solution enables competitive cost of electricity and water. The present project is critical to demonstrate the W2EW solution in a real-life environment, to reduce the risk profile of the solution and to build the market to pave the way for broad market roll-out. The scope of the paper is to introduce the project W2EW and its expected results to a broader audience.

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In wave renewable energy, the Capital Expenditure (CapEx) is often a fixed number or depends on a single variable (e.g. power or converter characteristic mass). Hence, it poorly highlights the CapEx dependency on the Wave Energy Converter (WEC) and Wave Energy Farm (WEF) design, which in turn depend on the site characteristics. As, most of CapEx components are accessible by wave companies nowadays, this article introduces the new generic CapEx method. This method is divided into three steps: (1) distinguishing WEC’s elements from the WEF’s; (2) defining the parameters characterising the WECs, WEFs, and site locations; and (3) estimating elements that affect WEC and WEF elements’ cost and translate them into factors using the parameters defined in step (2). The case study is based on Wavepiston because of its advanced stage and the availability of its WEC information and costs. The focus of this study is on the detailed application of step (1) and (2) to Wavepiston, to estimate the Wavepiston WEC cost using step (3). This study also illustrates how to handle complex and limited datasets of WEC configuration and site characteristics. Moreover, the results from the CapEx method were validated by manual estimations from Wavepiston. It was found for Wavepiston WEC, the site characteristics were the least affecting parameters in comparison to the WEC configuration parameters. This study also applies another parameterised cost calculation method based on the Froude law similitude as a simpler but more rigid alternative, for the CapEx method. It was shown that with appropriate scaling parameter, the Similitude method provided similar, although higher, estimations than the CapEx method’s within low ranges of WEC up-scaling. In high ranges of up-scaling, the Similitude method overestimated Wavepiston WEC cost.