Jesse Roberts and Jason Heath of Sandia National Laboratories attended the 4th General Meeting of Optimal Design Tools for Ocean Energy Arrays Project (DTOcean) in Madrid, Spain, October 27–29, 2015. This project is developing a whole-system software design tool for determining levelized cost of electricity (LCOE) for the design and implementation of first generation wave and tidal energy arrays. The DTOcean consortium, which includes 18 members from academia, industry, a US national lab (Sandia), and three field site developers, is positioned to develop and validate the whole-system tool. The components or “modules” of the DTOcean Tool will assess the following: hydrodynamics, array layouts, power output; electrical sub-systems; mooring, foundation and anchor systems and designs; logistics for installation, operations, maintenance, and reliability; economics; and environmental impact. The DTOcean Tool will integrate and facilitate communication between the modules with the goal of determining and optimizing LCOE.

At two years into the three year project, with much development completed on the individual modules, the meeting focused on two major items:
1) better understanding the inter-dependencies of the individual DTOcean modules; and
2) identifying a clear and acceptable path for completing the integration of the modules into a single DTOcean Tool that comprises the best functionality and enables global optimization for minimizing LCOE.

Day 1 included presentations to the strategic advisory board. The status and capabilities of the various modules were discussed. Mathew Topper of Tecnalia presented an initial version of the graphical user interface and demonstration of the DTOcean Tool, which highlighted how the tool may reveal controls on LCOE as a function of user-inputs or sensitivity analysis on decision variables (e.g., array spacing, foundation/anchor type and design, etc.). Days 2 and 3 involved many break-out sessions for team members working on individual modules. The sessions focused on finalizing the remaining calculation algorithms and data requirements needed for full assembly of the modules for the global calculation of an array design (including all components and maintenance requirements) and LCOE. The final group presentation discussed the strengths and limitations of optimization methods to that may be implemented to minimize LCOE as the goal, given constraints and decision variables that would be user-specified.