en.Wedoany.com Reported - Researchers at ETH Zurich have developed a novel direct air capture (DAC) method that uses protein beads made from dairy and soybean processing waste to capture carbon dioxide, reducing desorption energy consumption to a low level. The findings have been published in the Proceedings of the National Academy of Sciences (PNAS).
According to the latest assessment report by the Intergovernmental Panel on Climate Change (IPCC), limiting global warming to 1.5°C requires significant emission reductions and the development of technologies to remove and store carbon dioxide from the atmosphere. For a long time, DAC technology has been constrained by high energy consumption and costs, limiting its large-scale application. Climeworks, founded in 2009 and originating from ETH Zurich, is one of the world's first commercial DAC suppliers.
A team led by ETH Zurich professor and materials scientist Raffaele Mezzenga isolated proteins from whey and tofu production waste, processed them into amyloid fibrils, and loaded them with potassium hydroxide to create porous protein beads with diameters of 0.5 to 1 centimeter. The potassium hydroxide in the beads reacts with carbon dioxide in ambient air to form bicarbonate, achieving capture. In ambient air tests, 1 gram of material extracted 97 milligrams of carbon dioxide, with an absorption capacity 10% to 50% higher than traditional DAC methods. It is estimated that 1 kilogram of protein beads can bind and sequester 100 grams of carbon dioxide per process cycle.
Unlike traditional DAC, which requires heating and negative pressure for desorption, the team alternately sprayed the beads with mild acid and alkali at room temperature for about 10 minutes, releasing carbon dioxide by breaking chemical bonds. The acid, alkali, and beads are all reusable. In laboratory tests over 30 adsorption and desorption cycles, no significant efficiency loss was observed. The research team stated that although the material needs replacement after thousands of cycles due to decreased adsorption capacity, the used beads, made from organic materials, can be used as agricultural fertilizer or converted into biofuel. Lifecycle analysis shows that this method generates less environmental pollution than other DAC methods.
In the latest study, researchers used a few grams of protein beads in a controlled laboratory setting to bind and sequester about 50 grams of carbon dioxide. Mezzenga believes that the spray system used for desorption is based on existing industrial technologies. Although the cost per ton of carbon dioxide captured has not been precisely estimated, Mezzenga expects it to be lower than traditional DAC, primarily due to low energy consumption and the widespread availability of waste materials as raw inputs. Future scalability tests will be further advanced by postdoctoral researcher Zhou Dong.
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