Co-located storage could be the key to reducing wave energy LCOE

Cutting down costs of commercial-scale marine energy projects is one of the main challenges technology developers face when competing with other renewable energy sources, such as solar and wind.

Oscilla Power has recently completed an investigation into the value of energy storage when combined with wave energy.

The Seattle-based company is known for its Triton wave energy converter project, supported by the US Department of Energy (DOE).

According to Oscilla, substantial improvements in value and power quality can be realised for larger-scale wave farms with co-located energy storage systems.

Importantly, it was found that the quantity of storage required to achieve constant grid-quality power was much lower than either an equivalent wind or solar project.

The study also revealed that when a suitable energy storage system was coupled with a large-scale wave energy application, significant advantages in terms of cost, capacity and performance could be realised.

The consistency of the wave resource and better alignment with grid demand resulted in a lower capacity of storage (kWh) required for the same performance when compared to an ‘equivalent energy’ solar or wind project.

The performance metrics assessed in this study were (1) avoided generation, (2) microgrid penetration, (3) peak submarine line power, (4) peak transmission line power and (5) dispatchability.

Of particular importance, the investigation demonstrated that wave energy can achieve a dispatchable performance with lower quantities of storage than solar or wind, enabling wave energy to be sold when it is most valuable to the market.

The study was completed using data from Humboldt Bay, California.

The target storage performance could be achieved with underwater compressed-air energy storage (UW-CAES) technology. Synergies of co-locating this unique technology with a wave energy project suggest that much lower storage costs can be realized compared to other energy storage approaches.

However, for smaller projects that comprise only a low number of WECs, the study found that an on-board battery storage option would be the preferred technology choice.

A Li-Ion battery storage system could provide 5-10 MWh (1-2 days) of onboard storage and although it has a higher cost per-unit than large scale UW-CAES, it was still able to provide competitive power costs relative to wind in a remote microgrid application.

Furthermore, it was found that for the small microgrid scenarios studied, wave energy with storage can provide a much larger penetration of supply than either wind or solar.

In summary, Oscilla said that co-located storage at either the device or farm level appears to be a critical component in achieving substantial reductions in wave energy levelised cost of energy (LCOE).

The Triton-C is a 100kW community-scale wave energy system developed to provide power to remote communities and facilities.

The initial construction of the hull of Oscilla Power’s Triton-C WEC took place at the end of 2019.

Seattle-based Snow & Company is the primary contractor for the construction of the Triton-C and work is being completed at their facility in Ballard.

Detailed design for the Triton-C has been completed by naval architects Glosten, also located in Seattle, and who have been working closely with both Oscilla and Snow to ensure that the hull construction progressed smoothly.

Following the hull construction, Oscilla started work on the internal systems (‘drivetrains’) that will convert the wave-driven motion of the Triton-C into electricity that will be exported to shore.

These drivetrains are a proprietary hydraulic/electrical design that enables high efficiency power conversion with high reliability.

Tim Mundon, vice president of engineering at Oscilla Power, said: “The Triton-C, a 100kW community scale variant of our larger, 1MW Triton, is nearing final construction and should be completed in Q3 this year. Our hope is that it will be deployed at WETS in Hawaii by early next year.”

It is expected that the prototype Triton-C will be tested for a year in Hawaii before being bought back to Washington state where it will generate power commercially.