Researchers at ETH Zurich have developed protein beads made from dairy and tofu processing waste that can directly remove carbon dioxide from the atmosphere, offering a new approach to carbon capture technology.
The innovation converts protein-rich food industry by-products into reusable materials capable of capturing CO₂ from ambient air.
Scientists say the material absorbs more carbon dioxide than many existing direct air capture systems. It also requires significantly less energy during operation, helping address one of the biggest challenges facing carbon removal technologies.
The development comes as governments and industries seek new ways to reduce greenhouse gas emissions and meet climate targets.
Experts widely view carbon removal as an important complement to efforts to reduce emissions. Current direct air capture systems can be effective, but they are often expensive and energy-intensive.
The ETH Zurich team believes its protein-based approach offers a more sustainable alternative. By using waste materials as raw materials, the technology also supports circular-economy principles and reduces industrial waste. Researchers are now exploring how to scale up the system for larger carbon capture applications.
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How Protein Beads Capture Carbon Dioxide
The new research, published in the journal PNAS, takes a different approach. Instead of relying on synthetic materials, the team uses proteins recovered from waste streams generated during food production. This helps create a more sustainable and potentially lower-cost solution.
Large quantities of protein-rich liquids are produced during dairy and tofu manufacturing. Only a portion of these materials is reused in food products. The remainder often becomes waste.
Researchers extracted proteins from these leftover materials and transformed them into long structures called amyloid fibrils. These fibrils were then combined with potassium hydroxide. The resulting mixture was shaped into porous beads measuring between 0.5 and 1 centimeter in diameter.
The beads act like tiny sponges. Their porous structure allows air to pass through while exposing the potassium hydroxide to carbon dioxide. This enables the material to capture greenhouse gases efficiently.
When air comes into contact with the beads, potassium hydroxide reacts with carbon dioxide. The reaction produces hydrogen carbonate, a carbon-containing salt. In this way, carbon dioxide is removed from the surrounding air and stored within the material.
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Laboratory tests produced promising results. Researchers reported that one gram of the material captured 97 milligrams of carbon dioxide from ambient air. According to the team, this performance exceeds many conventional direct air capture materials.
The researchers estimate that one kilogram of protein beads can capture about 100 grams of carbon dioxide during a single operating cycle. This high absorption capacity makes the material attractive for future large-scale applications. It also demonstrates the value of turning industrial waste into useful climate technologies.
Lower Energy Demand and Circular Economy Benefits
A major advantage of the new system is the way captured carbon dioxide is released. Conventional direct air capture facilities typically use high temperatures and vacuum systems to separate carbon dioxide from capture materials. These processes consume substantial amounts of energy.
The ETH Zurich team developed a much simpler method. They alternately spray the protein beads with a mild acid and a mild base at room temperature. This process takes about ten minutes and releases the stored carbon dioxide.
The approach avoids the need for intense heating. As a result, overall energy consumption is significantly lower. Reducing energy demand is one of the most important factors in making carbon capture more affordable.
Another benefit is durability. Many synthetic carbon capture materials gradually lose effectiveness and need frequent replacement. The protein-based beads showed strong stability during laboratory testing.
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Researchers completed 30 cycles of carbon dioxide capture and release without seeing major performance losses. This suggests the material can be reused many times before replacement becomes necessary. Long service life can reduce operating costs and environmental impact.
The team believes the beads can remain useful for thousands of cycles. Eventually, their capture capacity declines as the material ages. Even then, the beads retain value because they are made entirely from biodegradable organic materials.
Instead of becoming waste, the used beads can serve new purposes. Researchers say they can be applied as agricultural fertilizer or converted into biofuel. This creates opportunities for a circular economy where materials continue to deliver value after their primary use.
The materials used in the process are also non-toxic and food-grade. This reduces concerns about environmental contamination during manufacturing and operation. Safety and sustainability are important advantages as carbon capture technologies move toward broader adoption.
The researchers also conducted a life cycle assessment. Their analysis showed lower environmental impacts across the entire system compared with several existing direct air capture methods. This strengthens the case for using biological materials in future carbon removal systems.
The study was carried out on a small laboratory scale. Researchers used only a few grams of protein beads and successfully captured and released around 50 grams of carbon dioxide. Larger-scale testing will be required before commercial deployment becomes possible.
Professor Raffaele Mezzenga, who led the research team, believes the technology can be scaled up. He has worked with amyloid fibrils for nearly two decades and previously used them in biodegradable plastics and water purification systems. His experience provides confidence that industrial applications can be developed.
The carbon release system also aligns with equipment already used in many industrial processes. This could simplify future integration into existing facilities. Easier deployment often helps reduce commercialization costs and speeds up adoption.
Researcher Zhou Dong is continuing work to evaluate large-scale performance. Future studies will examine whether the material maintains its high capture efficiency under industrial conditions. These tests will be critical in determining commercial viability.
The technology arrives as governments and industries increase investment in carbon removal solutions. Demand for affordable and energy-efficient systems continues to grow worldwide. Innovations that combine waste recycling with climate action are attracting particular attention.
If large-scale testing confirms the laboratory results, the protein-bead technology could offer a practical new pathway for removing carbon dioxide from the atmosphere.
By turning food industry waste into a reusable carbon capture material, researchers have demonstrated a solution that connects climate goals, resource efficiency, and sustainable manufacturing. The next phase of development will determine how quickly this promising approach can move from the laboratory into real-world carbon removal projects.
