Abstract
This paper presents the methods developed
and key findings of the IWEC project performed by Ocean
Harvesting Technologies AB (OHT). It aimed to reduce the
levelized cost of energy (LCoE) of OHT’s wave energy
converter InfinityWEC, by analysing how different key
parameters impact cost and annual output using a model of
a 100-MW array installation. Component-level cost
functions were developed and mapped to key parameters
and constraints of the system. A large number of system
configurations were then evaluated with a numerically
efficient 3 degree-of-freedom (DoF) nonlinear radiationdiffraction
model in WEC-Sim along with OHT’s sea statetuned
polynomial reactive control (PRC). The most
promising configurations were identified and investigated
in more detail. The configuration with the best LCoE were
finally identified and analysed further, including
estimation of the effect of changing the PRC to model
predictive control, which resulted in 17-34% higher annual
output and 12-23% lower LCoE. The final LCoE was found
to be 93 – 162 EUR / MWh at 100 MW installed capacity. An
important finding from the study is that using simplified
metrics such as CAPEX/ton was found to be irrelevant.
Numerical wave tank testing, high-fidelity computational
fluid dynamics (CFD), were used to tune the viscous drag
of the 3 DoF WEC-Sim model. Applying verification and
validation (V&V) techniques the CFD simulations showed
a relatively large numerical uncertainty, but the average
power and the motion responses were found to be
sufficiently accurate.