CARBOGEM
Final CARBOGEM artificial reef module prototype © Clara Schmelter de Escobar
Final CARBOGEM artificial reef module prototype © Clara Schmelter de Escobar
Oyster shell waste from New York Restaurants © Clara Schmelter de Escobar
Light microscope image of CARBOGEM material © Clara Schmelter de Escobar
Scanning electron microscope image of CARBOGEM material @ Juliane Posseckardt, Fraunhofer IKTS
CARBOGEM is a reef restoration module. Made from a novel material that uses photosynthetic cyanobacteria to bind 100% renewable ingredients into CO2-fixing concrete. Turning carbon into gems.(2024)
Oyster shell waste from New York Restaurants. © Clara Schmelter de Escobar
Oyster concrete samples submerged in water, cyanobacterial culture (right) and nutrient medium (left). © Clara Schmelter de Escobar
Oyster concrete samples submerged in nutrient medium and cyanobacterial medium. © Clara Schmelter de Escobar
CARBOGEM artificial reef module prototype being colonized with cyanobacteria in a light box. © Clara Schmelter de Escobar
The Anthropocene has caused a global decline in oceanic ecosystems, with reefs being amongst the most sensitive. In temperate zones, oysters are the keystone species that create these biodiversity hotspots. Sadly, due to human activities such as pollution, overfishing, rising temperatures, and ocean acidification, 85 percent of the world’s oyster reefs have already died off.
Not only marine life, but also coastal communities depend on the vitality of oyster reefs, as they provide essential ecosystem services like water filtration and coastal protection from floods and erosion.
Many initiatives are therefore attempting to restore these ecosystems with the help of artificial reefs. A variety of materials and designs are being tested, mostly made from concrete. However, the common material choices can be environmentally problematic as they are non-renewable or release CO2 during production, partially contributing to the problem themselves.
CARBOGEM is an artificial reef module made from a novel concrete developed in collaboration with Fraunhofer Institute. The material is based on renewable resources, with recycled oyster shell waste as the main component. Instead of using common cement for binding the oyster aggregate, it aims to use biocementation conducted by photosynthetic cyanobacteria. This approach can fix atmospheric CO2, converting the modules into carbon sinks.
The CARBOGEM modules are designed to be bioreceptive to marine organisms and initiate the growth of a healthy reef ecosystem. From the material composition, porosity and surface structure that attracts oyster larvae, to the topology that provides habitat for a variety of local reef flora and fauna.
The modules have dimensions of 25x25x10cm, making them easy to transport by boat and deploy by divers into the desired structure, eliminating the need for heavy-duty machinery. For monitoring purposes, single modules can be resurfaced and analyzed for colonization.
The modules' shapes are designed to self-assemble and interlock into rigid structures with increased surface area for quick oyster attachment and subsequent reef formation. In this case, the whole structure will be overgrown and absorbed into a reef.
Nevertheless, even before colonization, the structures themselves act as coastal protection by dissipating wave energy, preventing erosion, and thereby protecting the coastlines from sea-level rise and floods.The layout of the structures can be individually adapted to local conditions, such as undulating sea floors, coastlines, and specific restoration goals. For example, the modules can be used to bridge existing reefs and form protective corridors for marine life to migrate and populate new habitats. Another option is the initiation of a new reef in a suitable area or the securing of unstable substrate that has been damaged by ships.
In the case of unsuitable conditions, and absent colonization by oysters, the modules can either be entirely reused, reassembled elsewhere, or remain on the seafloor indefinitely, as they are 100% bio-based, non-toxic, and capable of locking away the contained carbon, acting as a long-term carbon sink. Turning carbon into gems.
CARBOGEM is my Bachelor's graduation project from the University of the Arts Berlin.
Read my full thesis here: https://drive.google.com/file/d/1AJR85-ev9Ddiz5yfiGkTkdEH4iS8V__9/view?usp=drive_link