Abstract
WATER BROS Desalination, LLC. designed, simulated, built, wave-tank tested, and open-ocean tested a wave-powered desalination device for the US Department of Energy's Waves to Water Prize. The Wave-Actuated, Tethered Emergency Response Buoyant Reverse Osmosis System (WATER BROS) is a modular, rapidly deployable, direct-drive desalination system harnessing the power of near-shore wave energy. The Waves to Water Prize challenged teams to conceptualize, design, and construct small-scale wave energy converters (WECs) that can quickly be deployed in response to a coastal or islanded area disaster to provide potable water to recovering residents. Wave-powered desalination is one of the markets explored in the US Department of Energy's Powering the Blue Economy initiative as a steppingstone to further marine energy development.
The WATER BROS device was designed to fit in a standard shipping crate, be transported in a small pickup truck or equivalent, and can be deployed with 2-3 personnel without specialized training or equipment. Additionally, the device was designed to be deployable without assuming the presence of any coastal infrastructure such as a pier, which may be absent, unavailable, or damaged in the aftermath of a disaster.
Throughout the competition, the team used physics-based models of their WEC developed in MATLAB and Simscape to model loads, energy recovery, and water production. Small-scale prototypes were manufactured and deployed in open-ocean to validate the simulation models, and inform design iterations for form-factor, hydrodynamic stability, and capsize prevention and recovery. Then the team performed wave-tank testing of a full-scale prototype was at the University of New Hampshire Jere A. Chase Ocean Engineering Laboratory, where desalinated water production was 83-89% of the values predicted by the Simscape models. Those models were used to tailor the system performance to the wave conditions at Jennette's Pier in North Carolina, USA, where the final demonstration/testing was held in April 2022.
The system successfully produced desalinated water before an unexpectedly energetic storm compromised the moorings of all 4 teams during the testing. This presentation is focused on the successes and failures that occurred throughout the 2+ year project and how those lessons learned are informing design refinements in a new iteration of the device. The team identified early and frequent prototyping as a strength as well as use of existing resources in the development of the design. Recognizing that device deployment will involve new parties, the team has realized that additional features to clearly identify components on the device would be warranted. Finally, though it was outside the requirements for the Waves to Water Prize, the team sees the need for a stronger more robust data collection approach to avoid missing out of on important data during a deployment.