The U.S. Department of Energy’s Wave Energy Prize Competition encouraged the development of innovative deep-water wave energy conversion technologies that at least doubled device performance above the 2014 state of the art, based on U.S. reference models. Because levelized cost of energy (LCOE) metrics are challenging to equitably apply to new technologies where significant uncertainty exists in design and operation, the prize technical team developed a reduced metric as proxy for LCOE, which provides an equitable comparison of low technology readiness level wave energy converter (WEC) concepts.
The metric is called “ACE” which is short for the ratio of the Average climate capture width to the Characteristic capital Expenditure.1 ACE can be thought of as the equivalent wave crest width, for which the wave energy converter can absorb all incoming wave energy, that can be built per million dollars spent on load bearing structure. The value of ACE for 2014 state-of-theart deep-water WEC technologies was estimated at 1.5m/$M for deployment on the West Coast of the United States, yielding a prize threshold of 3.0m/$M when doubled. To account for additional important characteristics that affect the LCOE, the resulting ACE value is multiplied by a performance-based scale factor called hydrodynamic performance quality, determined from other data collected during testing.
Each of the prize finalists tested technologies at the Naval Surface Warfare Center, Carderock Divisions’ Maneuvering and Sea Keeping test facility to provide measured performance and other data. Finalists were provided separate one-week access to the testing basin where their devices were subject to 10 different sea states. These sea states were selected to be representative of operating and energetic conditions on the West Coast of the United States.
The methodology and application of the ACE metric used to evaluate the performance of the technologies that competed in the Wave Energy Prize are explained herein. First, an overview of the prize is presented with details on the development of the ACE metric. Next, the average climate capture width calculation is described. Finally, the methodology used to calculate the characteristic capital expenditure is described.