Underwater sunlight through the water surface seen from a rocky seabed with algae in the Mediterranean sea, natural scene, Catalonia, Costa Brava, Spain
Damedias/Adobe Stock Underwater sunlight through the water surface seen from a rocky seabed with algae in the Mediterranean sea, natural scene, Catalonia, Costa Brava, Spain

The increased demand for raw materials and shrinking land area for natural resources have encouraged product manufacturers to look to a new supply source: the ocean. The so-called blue economy includes marine-based resources, such as algae and seaweed, that may be employed for food, energy, medicine, clothing, and other uses. The blue economy is also fertile territory for building products sourced from bio-based (also called blue biotechnology) and abiotic materials. The examples ahead, organized from living to mineral-based sources, illustrate some of the possibilities in this emerging area of development.

Seaweed is a plentiful marine resource with many potential uses. “Today, it is probably easiest to use seaweed in food,” explains Northern Company CEO Zoe Christiansen, whose Norway-based outfit harvests the stuff. “But seaweed can also be processed into biofuel, fibers for the textile industry, and alternatives to plastic.” Melbourne, Australia-based Phycoforms manufactures engineered composite building modules from compressed seaweed. The company creates a slurry composed of seaweed, a natural binder, and fire retardant, which it presses into molds for bricks or sheets for interior construction.

Microalgae is another versatile blue economy material. Colorado company Prometheus Materials manufactures algae-based cement and concrete materials that exhibit a net-zero carbon footprint. Commercialized products include concrete masonry units, pavers, retaining wall modules, and acoustic panels. The company fabricates these products using a biomineralization method initially developed at the University of Colorado Boulder. Similar to how coral reefs form, the process produces cementitious materials with a similar mechanical performance as those that consist of Portland cement—but with much lower carbon emissions.

“By working with nature to use existing microalgae to bind minerals and other materials together to create new types of sustainable bio-composite building materials, we can eliminate most, if not all, of the carbon emissions associated with traditional concrete-based building materials,” company co-founder Wil Srubar claims. Notably, SOM’s recent Bio-Block Spiral installation in Chicago utilizes Prometheus Materials’ algae-based bio-concrete.

Another material called bio-concrete by its creators is an unusual hybrid between Japanese knotweed and crayfish shells. The two organisms are considered invasive species in the UK, where designers Brigitte Kock and Irene Roca Moracia developed the new composite. Part of a so-called “traveling species” collection known as En Route, the bio-concrete tiles employ ash and root powder from Japanese knotweed in combination with powdered American Signal Crayfish shells. According to the designers, the new material becomes more robust over time and—like ancient Roman concrete—can safely resist corrosion when submerged in seawater, unlike modern concrete.

Seashells are the raw materials in Sea Stone, a cementitious product created by Seoul, South Korea- and London-based design firm Newtab-22. According to the founders Hyein Choi and Jihee Moon, the fishing industry discards seven million tons of seashells annually, and most of these shells end up in landfills. Far from a worthless byproduct, seashells have a high percentage of calcium carbonate similar to limestone and are a valuable feedstock for mineral-based materials. To manufacture Sea Stone, Choi and Moon gather unwanted seashells from the seafood industry and grind them into calcium-rich powders with other natural binders to make durable decorative tiles.

On the more experimental side, Dutch architect Eric Geboers promotes the use of sea salt to create building structures in arid regions. Based on explorations of salt-based 3D printing by San Francisco–based Emerging Objects, Geboers has proposed building modules made of salt that can support larger structures. By itself, salt is an impractical material for construction. However, the addition of maltodextrin, isopropyl alcohol, and water creates a smooth slurry that can be easily 3D-printed into modular units. Once fabricated, these modules are sufficiently rigid to retain their shape and support more weight. The addition of a glycerol-based epoxy provides enhanced surface protection. The resulting salt bricks exhibit a compressive strength and density that approximate rammed earth or ice. Thus, they are suitable for building structures of a similar thickness and geometry—such as load-bearing barrel vaults.

Despite the promise of blue economy resources, the increased harvesting of ocean-based materials poses ecological risks. Global warming, overfishing, and pollution are already deteriorating the health of marine-based ecosystems, and elevated prospecting will result in further degradation without clear environmental protection strategies. With this goal in mind, manufacturers should prioritize using excess oceanic materials whose presence is either harmful or has no direct ecological value—such as invasive species, excess sargassum on beachfronts, or discarded seashells from the food industry. Second priority can be given to materials in significant abundance, such as microalgae or sea salt, whose limited depletion is not likely to cause an ecological imbalance. Perhaps most importantly, manufacturers and designers should view the blue economy not as a one-way extraction process, but as a two-way interchange—and seek to support marine ecosystems via projects like artificial coral reefs in return for harvested resources.

The views and conclusions from this author are not necessarily those of ARCHITECT magazine or of The American Institute of Architects.

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