Improved On-Board Energy Storage for Wave Energy Convertors

Wave energy can provide power that is better matched to local demand and more consistent than other variable renewables. However, it has an inherently high short-term variability compared to other variable renewables which drive up costs. In particular, the electrical systems need to be designed for the peak power, which can be much greater than rated power. This is especially impactful in utility-scale arrays where the electrical infrastructure can be a significant part of total capital cost. Co-locating an energy storage system with a wave energy project has been shown in to significantly mitigate the short-term power variability and allows power to be preferably dispatched using much lower levels of storage than needed for solar or wind. OPI will work with Brayton Energy and other partners to develop an Underwater Energy Storage System (UW-ESS) that can be co-located with a wave energy project. OPI will investigate what level of power variability can be expected from an array of wave energy convertors. Determining WEC array output is complex and the layout will drive the output power far more than seen in wind or solar arrays. By co-locating an UW ESS with the WEC array, we can use the storage to manage power flows between the array and shore and minimize the costs associated with the export cable and grid connection. In the Phase I program, Oscilla demonstrated that a UW ESS co-locatedoffshore with a large array of wave energy devices is able to add significant value to the power provided. It was further demonstrated that the ESS for a wave energy project can have a much lower power rating (and hence capital cost) than for an equivalent solar or wind project. OPI identified a suitable UW ESS technology that can provide suitably large capacities and be cost effectively co-located with a wave project. In the proposed Phase II program, OPI will investigate the power quality produced from a large array of Triton WEC’s to understand how the short-term energy variability changes with array spacing and layout. This output will be used to develop the electrical design for the array and develop an engineering design for the identified UW ESS technology. Ultimately this design will be evaluated as a case study and used develop accurate cost, LCOE and utility-derived performance metrics. The addition of energy storage to large arrays of Triton WEC’s can make a meaningful impact on reducing the overall LCOE such that it can compete effectively against not just other renewables, but also potentially against conventional sources of electricity. This can open up ocean wave energy as a viable new renewable energy source and if this work is successful in catalyzing the introduction of wave energy to the utility power mix, will result in new high-paying manufacturing and installation jobs.