There are many unique technologies aimed at tackling rising CO2 levels entering the market today. One such technology hopes to overcome the unique challenges posed by high-density urban environments where space limitations can impede clean air, carbon capture, and cooling efforts. Compact algae systems could provide an effective solution by mimicking the benefits of mature trees in a compact package.
This technology is being pioneered by the Institute of Multidisciplinary Research at the University of Belgrade. The project is called Liquid 3 and has been highlighted by the United Nations Development Programme as an innovative solution for climate-smart urban development. The team there has developed an innovative design to absorb CO2 and release oxygen using microalgae, and it’s already demonstrating how advanced urban greening solutions can fit within even the most space-constrained environments.
How Algae Powers CO2 Absorption
The Liquid 3 project has created a type of photobioreactor consisting of a transparent tank filled with microalgae. As the algae grow, they convert CO₂ into oxygen through photosynthesis, just like they do in their native environments. This can achieve similar results to a mature tree without the decades of growth required for maturity. Instead, Liquid 3 photobioreactors start working from the moment of installation.
Photo: Liquid 3
The compact photobioreactors have a footprint of roughly 2 feet by 3 feet, making them easy to slot into any available space. They are purported to deliver the same air quality improvement as a 20-year-old tree. The system also incorporates solar panels to provide additional quality-of-life benefits for city inhabitants, such as street lighting and mobile charging. Some versions also feature a bench as part of the overall construction. It serves as a multifunctional piece of infrastructure that delivers many benefits.
The Environmental Benefits of Algae-Based Technologies
Microalgae technology drives Liquid 3, and it’s also being used in a wide range of other sustainable technologies, from renewable fuels to sustainable food systems. Another prime example of a modern application using microalgae is the biofuel project under development by Viridos. In partnership with ExxonMobil, the company has received $25 million in funding to advance commercial-scale algae biofuel development, generating renewable fuel that can be used in current diesel and aviation applications.
Denmark’s Algiecel is also developing algae bioreactors that capture CO₂ from the environment. However, their aim is to produce biomass that can be used in animal feed and even human food products. Unilever has partnered with Algenuity to explore similar technology in algae-based food protein applications. These are just a few examples of the innovative projects underway surrounding microalgae and its use in sustainable technology.
Algae CO2 Absorption in Practice
Claims from Liquid 3 indicate that their current design is highly effective in achieving CO₂ reduction and oxygen generation in confined spaces where planting trees may not be viable. Once installed, the system requires maintenance every six weeks to remove accumulated algae, which is currently repurposed as fertilizer.
One of the most significant hurdles for the project to overcome is cost. Each unit currently ranges from $10,000 to $15,000, with that investment covering the photobioreactor and installation. Ongoing maintenance costs are also a concern. There is also ongoing debate over whether these types of solutions should be a primary focus in CO2 reduction as opposed to more traditional ecological restoration efforts.
Adoption of Liquid 3 Photobioreactors in Urban Environments
The first functional Liquid 3 photobioreactor was put into action in Belgrade in 2020, with the project receiving recognition from the UNDP and Serbia’s Ministry of Environmental Protection. There have been multiple additional installations in Serbia since, with further deployments planned in Paris, New York, and New Delhi.
Photo: UNDP / Vladimir Zivojinovic
There are many potential reasons why a city might choose to install Liquid 3 photobioreactors. Planting trees can be challenging due to soil constraints, underground infrastructure, and limited space. Liquid 3 units fit easily into public plazas, bus stops, and other areas to retrofit existing environments to meet air quality and climate goals.
Looking Forward to a Sustainable Future
Projects like Liquid 3 offer unique solutions to complex problems while working around the practical constraints of urban environments. Whether or not this specific project achieves widespread adoption, it demonstrates the spirit of innovation that will play a key role in addressing the climate and air quality challenges of the future.
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