Abstract
The U.S. Department of Energy (DOE) estimates that the theoretical average annual energy available from ocean waves and currents is approximately 1,445 TWh/year, approximately one-third of the nation's total annual electricity usage. Although this estimate represents the theoretical upper bound of our nation’s marine energy resource, extracting just a small fraction of it by developing efficient and cost-competitive marine energy conversion (MEC) technologies could contribute significantly to the U.S. renewable energy portfolio and to efforts reducing carbon emissions. Further, most of this potential energy resource is close to large coastal population centers.
Determining how DOE can best support research and development (R&D) for MEC technologies requires the application of common performance metrics derived using uniform methodologies in order to benchmark a given technology’s performance and measure improvements to performance as it advances its technology performance level (TPL) and technology readiness level (TRL). This uniform assessment methodology is especially important given the diversity of MEC technologies being proposed. MEC technologies include current energy converters (CEC), which generate electricity from the hydrokinetic energy of moving water currents, and wave energy converters (WEC), which generate electricity from the hydrokinetic energy in waves. There are a multitude of CEC and WEC archetypes and deployment strategies. Unlike land-based wind energy, which converged on the three-bladed horizontal axis wind turbine (HAWT), there is no clear leading technology in marine energy to focus R&D efforts. CECs are predominantly analogues of HAWTs and vertical axis wind turbines (VAWT), and resources include river, tidal and ocean currents. WECs, generally have relatively lower TPLs and TRLs, and are more varied in their maturity, scale, and design.
The DOE’s reference model project (RMP) was a multi-year effort to develop and apply a uniform assessment methodology to benchmark the performance of MEC technologies. As part of this effort, a half dozen MEC technologies were designed to serve as reference models (RM). These RMs, paired with reference resource sites, allowed calculation of the Levelized Cost of Energy (LCOE) for single units to multiple-unit projects and a detailed cost breakdown structure to identify cost-drivers and to develop cost reduction pathways as detailed in Neary et al. (2014a), Neary et al. (2014b), Yu et al. (2015) and Bull et al. (2014). Data from the RMP was used to benchmark LCOE for small commercial scale MEC arrays of 10 MW installed capacity, as detailed by Jenne et al. (2015). The economic results from the RMP studies are reviewed herein.