A team of engineers from several institutions in China has developed an innovative dual-reactor system that could serve as a potential solution to two critical global challenges: climate change and food production. Published in the Environmental Science and Ecotechnology journal, their research highlights how the system converts carbon dioxide (CO2) into single-cell protein, a consumable food source, simultaneously reducing the amount of CO2 in the atmosphere. This achievement could mark a significant step toward more sustainable agricultural practices and carbon capture technologies.
The world is facing multiple interconnected crises: rising levels of greenhouse gases in the atmosphere, increasing food insecurity, and growing global populations. Climate change, driven by the accumulation of CO2, and the need for more sustainable and scalable food sources are two problems that demand urgent attention. The dual-reactor system developed by this team of chemical, industrial, and biotechnical engineers addresses both of these issues by using atmospheric CO2 to generate protein that could be utilized for both human and animal consumption.
The Structure and Function of the Dual-Reactor System
The dual-reactor system developed by the Chinese researchers functions in two distinct stages. In the first stage, microbial electrosynthesis (MES) is employed to convert CO2 into acetate, a short-chain organic compound that serves as a precursor or intermediary. The MES process makes use of microbes that utilize electricity, typically derived from renewable energy sources, to facilitate this conversion of carbon dioxide into organic molecules. In essence, CO2 from the air is captured and transformed into a usable feedstock—acetate.
The second stage of the system comes into play when the acetate produced in the first reactor is transferred into a second reactor. Here, acetate serves as a fuel source for aerobic bacteria. These bacteria consume the acetate and produce single-cell protein (SCP) as a byproduct. Single-cell proteins, also known as microbial proteins, are rich in essential amino acids and can serve as an efficient protein source for food. These proteins are highly nutritious and represent an increasingly viable alternative to conventional sources like animal-derived protein, soy, or other plant-based proteins.
This process essentially takes atmospheric CO2, a harmful greenhouse gas, and transforms it into a sustainable and valuable product—a high-protein source that is also less taxing on the environment than conventional agricultural methods. By using CO2 as the starting material, the system not only reduces harmful emissions but also produces a product that could play an important role in combating food insecurity.
High Efficiency and Nutritional Value
The results of the research showed promising outcomes in terms of both the efficiency of the system and the quality of the protein produced. The team found that the system was capable of achieving an impressive dry cell weight of 17.4 grams per liter (g/L), which is indicative of the high yield that can be achieved using this method. In terms of protein concentration, the protein produced by the system has a remarkable 74% protein content. To put this into perspective, this is significantly higher than other common protein sources such as soybean meal or fish meal, which are widely used in animal feed and some human diets.
This high level of protein concentration is crucial because it indicates that the system can be a viable and efficient method for producing high-quality protein at scale. Moreover, the researchers point out that the system can be applied to produce protein for both animal feed and human consumption. For animals, the high-protein product could serve as a sustainable alternative to traditional animal feed, which often involves resource-intensive production processes such as growing soybeans or feeding livestock with fish meal.
For human consumption, the protein produced through this method could contribute to alleviating the demand for traditional protein sources. As global populations increase, so does the pressure on food systems to supply sufficient protein to meet dietary needs. Single-cell protein made from CO2 may offer a more resource-efficient alternative that bypasses the need for traditional farming, which often requires vast amounts of land, water, and energy.
A Sustainable and Low-Cost Solution
Another key aspect of the dual-reactor system is its sustainability and cost-effectiveness. Traditional methods of protein production—such as the cultivation of crops like soy or the farming of livestock—can lead to significant environmental costs. These processes often require large amounts of water, fertilizers, and pesticides, contributing to soil degradation and environmental pollution. Additionally, they produce significant amounts of wastewater and waste products that need to be disposed of, adding further complexity to the agricultural process.
In contrast, the new dual-reactor system developed by the team in China operates with minimal pH adjustments. pH regulation is a common challenge in many biological processes, as it often requires the addition of acids or bases to maintain a stable environment for the microorganisms involved. By minimizing the need for such adjustments, the system reduces the operational complexity, and the associated cost, of maintaining an optimal pH level. Moreover, the process generates less wastewater compared to other protein production methods, which not only reduces environmental impact but also cuts costs related to wastewater treatment and disposal.
Overall, the streamlined operation of the system, combined with its low cost for maintenance and operation, makes it a much more economically viable option for mass-protein production compared to more traditional agricultural practices.
A Major Potential Impact for the Future
The implications of this dual-reactor system for both food production and environmental sustainability are profound. As the global population continues to grow—reaching an estimated 9.7 billion people by 2050—the pressure on food systems will only increase. Meeting the demand for protein in an environmentally responsible and cost-effective way will require finding new sources of protein that are not as resource-intensive as those commonly used today.
This new method of protein production, based on the conversion of CO2 into a food source, could serve as a critical piece of the puzzle in addressing food insecurity around the world. The ability to produce protein using atmospheric CO2 as the starting material would not only contribute to more sustainable food production but would also play a role in mitigating climate change by reducing greenhouse gases.
By tapping into the abundance of atmospheric CO2, this system offers a two-fold benefit: it contributes to food security while helping to limit the accumulation of carbon dioxide in the atmosphere. As a renewable source of food, the approach could be scaled up to meet the needs of communities worldwide without further exacerbating the environmental damage caused by traditional farming and livestock production.
Conclusion
In conclusion, the dual-reactor system developed by the research team represents an exciting breakthrough in both the fields of food production and environmental sustainability. By converting CO2 into a high-protein consumable product, this system offers a unique, innovative solution to two of the most pressing global challenges: climate change and food insecurity. Given its high efficiency, sustainability, and potential scalability, the system has the ability to be a game-changer in the effort to provide sufficient protein sources for a growing global population while simultaneously addressing the harmful effects of climate change. As the technology advances and moves toward commercialization, it holds the promise of making a lasting, positive impact on both human diets and the environment.
Reference: Zeyan Pan et al, Single-Cell Protein Production from CO2 and Electricity with A Recirculating Anaerobic-Aerobic Bioprocess, Environmental Science and Ecotechnology (2025). DOI: 10.1016/j.ese.2025.100525