Recently, Swiss scientists have developed a highly unique new type of “living building material.” It is a living gel composed of a material that can be 3D printed and undergo photosynthesis, able to continuously consume and store carbon dioxide from the air. Its efficiency is equivalent to a 20-year-old pine tree.
The team at ETH Zurich in Switzerland has created a “photosynthetic living gel” material that is vibrant, able to grow, and actively remove carbon dioxide from the air. This material has already been used in the field of architecture and made appearances at the 24th Milan Triennale and the 19th Venice Architecture Biennale, showcasing its sustainability and practicality.
By combining blue-green algae (PCC 7002) with a transparent gel (Pluronic F-127) that can be 3D-printed, the research team has induced the algae to photosynthesize, absorbing carbon dioxide (CO2) from the atmosphere to produce a reaction that results in carbonate precipitation (MICP), converting carbon dioxide into solid carbonates like limestone stored within the material to achieve carbon sequestration goals.
The photosynthetic living gel’s blue-green algae only require sunlight, nutrient-rich artificial seawater, and carbon dioxide to photosynthesize and grow for more than a year without needing to leave the material during the entire growth process.
To ensure the long-term survival and efficiency of the algae, researchers have optimized the geometric shape of the printed structure through 3D printing processes to increase surface area and light penetration, facilitating the flow of nutrients.
Results have shown that each gram of the photosynthetic living gel material can sequester 2.2 to 3.1 milligrams of carbon dioxide within 30 days, surviving for over a year (currently a record of over 400 days). Over 400 days, each gram of the material accumulates an absorption of 26 to 33 milligrams of carbon dioxide, mostly stored in a stable mineral form.
The amount of carbon dioxide absorbed by this material far exceeds other biological methods, comparable to the chemical mineralization of recycled concrete, with minerals inside the material recoverable by heating to 600°C. Additionally, the stability of storing carbon dioxide in solid mineral forms is superior to biomass (organic life or recently deceased biological matter).
The team printed the “photosynthetic living gel” into living volume blocks, assembling them into two trunk-shaped objects exhibited at the Canada Pavilion at the Venice Architecture Biennale. They mention that one trunk-shaped object can absorb 18 kilograms of carbon dioxide per year, equivalent to the carbon absorption of a 20-year-old pine tree in temperate regions annually.
Researchers believe that this photosynthetic living gel is a low-energy, environmentally friendly material that can open up new possibilities in the construction field by consuming and storing carbon dioxide from the atmosphere. Although there is still a long way to go, colleagues in the construction field have already embraced this new concept with initial successes.
They also state that future evaluations will be conducted on the amount of carbon dioxide sequestered by biomass to understand how different pH environments and carbon dioxide concentrations affect the rate of algae’s photosynthesis, aiming to enhance the system’s conversion efficiency.
The architect and bio-designer of this research, Andrea Shin Ling, a doctoral student at ETH Zurich, mentioned to the university’s press office that they have transformed the Canada Pavilion to provide sufficient light, humidity, and temperature to promote the growth of algae within the material for observation.
Co-first author Dalia Dranseike, from the Molecular Engineering Laboratory of the Department of Mechanical and Process Engineering at ETH Zurich, added, “Through structural design, we enable light to penetrate the material and passively distribute nutrients inside the structure through capillary forces.” Material researchers of the team reported that this design allows the algae encapsulated in the gel to survive efficiently for a year.
Mark Tibbitt, professor of Molecular Engineering at ETH Zurich, stated, “As a building material, the blue-green algae inside can directly store carbon dioxide within the building, enabling carbon to be stored in biomass and mineral forms. In the future, we hope to apply it to building exterior coatings for large-scale carbon capture.”
Another main author of the paper, Yi Fan Tsui, emphasized, “Blue-green algae are one of the oldest forms of life in the world. Their photosynthesis is highly efficient, capable of converting carbon dioxide and water into biomass even under the weakest light.”
He stated that they have utilized these abilities of blue-green algae in building materials, allowing minerals to deposit within the material, gradually hardening the originally soft material structure to enhance mechanical performance. The research findings have already been published in the journal “Nature.”