Scientists in Switzerland have developed an innovative new material made from food industry waste that could help remove carbon dioxide (CO2) directly from the atmosphere more efficiently and at a lower cost.
The research, led by scientists at ETH Zurich and published in PNAS, uses proteins extracted from waste products generated during dairy and tofu production.
The resulting material can capture significantly more CO2 than many existing direct air capture (DAC) technologies while requiring less energy to operate.
Direct air capture is a technology designed to remove CO2 from the atmosphere, helping to slow climate change.
Experts believe that reducing emissions alone may not be enough to limit global warming. Large amounts of CO2 already in the atmosphere may also need to be removed and stored.
Although DAC technology already exists, it remains expensive and energy-intensive. Companies such as Climeworks have built commercial systems, but researchers continue searching for cheaper and more sustainable alternatives.
The ETH Zurich team found inspiration in an unlikely source: food waste.
Large amounts of protein-rich liquid are left over during dairy and tofu production. Much of this material is discarded. The researchers extracted proteins from these waste streams and transformed them into tiny thread-like structures called amyloid fibrils.
They then combined these fibrils with potassium hydroxide and shaped them into porous beads about half to one centimeter wide.
The beads work like tiny sponges. When exposed to air, the potassium hydroxide inside the beads reacts with carbon dioxide and traps it in the form of a chemical compound called bicarbonate.
In laboratory tests, just one gram of the material captured 97 milligrams of CO2 from the air. According to the researchers, this represents a 10% to 50% improvement over many conventional direct air capture materials.
The team estimates that one kilogram of the beads could potentially capture about 100 grams of CO2 during a single operating cycle.
One of the most promising aspects of the technology is the low amount of energy required to release the captured carbon dioxide. Traditional DAC systems often rely on high temperatures, strong vacuum systems, or both. These processes consume significant amounts of energy.
The new beads use a much simpler method. Researchers alternately spray them with a mild acid and a mild base at room temperature. This breaks the chemical bonds holding the CO2, allowing it to be collected for storage or reuse.
The beads, acid, and base can all be reused multiple times. In testing, the material maintained its performance through 30 capture-and-release cycles with little loss of efficiency.
Eventually, after thousands of cycles, the beads may need replacement. However, because they are made entirely from biodegradable organic materials, they could be repurposed as agricultural fertilizer or converted into biofuel rather than becoming waste.
The researchers also found that the process creates less environmental impact over its entire life cycle than many existing DAC technologies.
Although larger-scale testing is still needed, the team is optimistic about the future. Because the material is made from widely available food waste, requires little energy, and uses non-toxic ingredients, researchers believe it could become a more affordable and sustainable way to remove CO2 from the atmosphere.
If successful at industrial scale, these humble protein beads could help turn food waste into a valuable tool in the fight against climate change.
