The limits of reduced order current energy converter modeling

Reduced-order models for mesoscale current energy converter (CEC) modeling allow for tractablecomputation times for investigations of array configurations on power performance and environmentaleffects to support design optimization. The CEC representation in these models take the form of actuatordiscs in codes such as SNL-Delft3D-CEC-FM treating the rotating CEC blades as momentum sinks. Inthe first-of-its-kind, whole-plant optimization software, DTOcean, the hydrodynamic modelling of CECsis reduced one step further by superimposing wake models based on normalized CFD simulations onto aset of pre-computed velocity fields, to provide power estimates. DTOcean is a new tool and the amountof verification and validation evidence gathered is presently limited. To gain additional confidence andindustry buy-in to the software penetration, this study investigated a primary component of levelized cost ofelectricity (LCOE) calculation, annual energy production (AEP), through an analytic calculation of powerusing the results of an identical simulation in SNL-Delt3D-CEC-FM. Three configurations of an 8-turbinearray are studied with DTOcean where two rows of 4-turbines are spaced (unstaggered) 5-, 10-, and 20-Diameters apart and the AEP was calculated; The energy calculation in SNL-Delft3D-CEC-FM were morecomputationally expensive for the mesoscale domain making the optimization of solely an arrays powerproduction using the wake superposition method implemented DTOcean attractive. The codes however arecomplementary as SNL-Delft3D-CEC-FM simultaneously investigates environmental effects of varyingarray configurations while DTOcean considers all aspects of array costs through its lifetime to optimizeLCOE from a whole-plant perspective.