Biodegradable Hulls Materials for Buoys—Towards Sustainable Oceanography

Global warming has caused changing climates, extreme weather events, and steadily increasing land and ocean temperatures. Given such negative impacts, it has become pivotal to have improved monitoring of ocean conditions for weather and climate forecasting. Researchers and governmental and private institutions use both surface-drifting and moored buoys to record oceanic and atmospheric properties, with an increasing number being deployed to achieve higher spatial and temporal resolution. Composed of several systems, buoys can be broken down into sensors, electronics, power generation and storage, communications, and the hull. Current buoy hulls, most commonly made from non-biodegradable polymers and alloys, perform throughout their service life before ending up as waste that often floats in oceans indefinitely. While our team addresses potential solutions in all buoy systems, considering cost and sustainablity in order to create buoys at scale, the work we present here focuses on efforts to create an alternative hull material from renewable biomatter. Our strategy is to utilize algae-based bioplastics to design a hull material that abides by green chemistry principles, remains intact during its service life providing a watertight interior, and at end-of-life degrades benignly into the ecosystem. We present the characterization of two sets of algal bioplastics which utilize either a microalgae (chlorella) or a macroalgae (+++) as their main matrix component, and are reinforced with natural additives. The structure, morphology, mechanical properties, and water performance of these materials are evaluated, along with processing methods to achieve the required mechanical strength. Additionally, we assess waterproofing strategies using protective coatings. The results demonstrate the potential of algae-based bioplastics as sustainable materials for environmentally-friendly ocean monitoring buoys.