A Chinese team has achieved a breakthrough! Seawater carbon capture costs just 1,600 yuan per ton, transforming CO₂ into biodegradable plastics like PBS and PLA
Faced with the dual challenges of global warming and marine ecological imbalance, transforming the vast amount of carbon dioxide in the ocean into valuable resources has become a pressing issue in the scientific community. On October 6th, a research finding published in the internationally renowned academic journal Nature Catalysis provided a breakthrough in this vision. This discovery, proposed and validated by Gao Xiang's team from the National Key Laboratory of Quantitative Synthetic Biology and the Institute of Synthetic Biology at the Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, and Xia Chuan's team from the University of Electronic Science and Technology of China, describes an "artificial ocean carbon cycle system" based on a coupled electrocatalytic and biocatalytic strategy. This system captures carbon dioxide from natural seawater and converts it into intermediates that can be directly used in biomanufacturing, and then further upgraded to a variety of high-value chemicals and materials.
As Earth's largest natural "carbon reservoir," the ocean absorbs over a quarter of anthropogenic carbon dioxide emissions annually. While mitigating global warming, it also contributes to the serious problem of ocean acidification. Converting dissolved carbon into usable resources is a crucial challenge for achieving both the "blue economy" and the nation's "dual carbon" goals.
The key innovation of this research lies in the synergistic coupling of electrocatalysis and biocatalysis. Xia Chuan's team at the University of Electronic Science and Technology of China pioneered a breakthrough in the technical bottleneck of seawater carbon capture. Their independently designed electrolysis device, which overcomes challenges such as electrode passivation and salt deposition, can operate stably and continuously in natural seawater for over 500 hours, capturing up to 70% carbon dioxide (CO2) and simultaneously producing hydrogen as a byproduct. The cost of capturing one ton of CO2 is calculated to be approximately US$229.9, demonstrating strong economic viability. The research team also developed a highly active and formic acid-selective bismuth-based catalyst (Bi-BEN), which efficiently converts captured CO2 into formic acid through electrocatalysis. The scaled-up electrolysis system operated stably for 20 days continuously, producing a high-concentration, pure formic acid solution, providing a stable feedstock for subsequent bioconversion.
However, despite the availability of this key intermediate, formic acid's biotoxicity hinders its efficient utilization by most microorganisms. To this end, Gao Xiang's team at the Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, constructed a "supercell" capable of efficiently utilizing formic acid and converting it into plastic monomers. Using the extremely fast-growing marine bacterium Vibrio natrii as a base cell, the team successfully engineered a strain capable of tolerating high concentrations of formic acid and efficiently growing and metabolizing it using it as a sole carbon source. This engineered strain can precisely convert formic acid into succinic acid, the core monomer for the biodegradable plastic polybutylene succinate (PBS), and lactic acid, a monomer for the biodegradable plastic polylactic acid (PLA).
To verify the carbon flow and industrial feasibility of the entire system, the researchers used carbon isotope (13C) labeling experiments to confirm that the carbon atoms in the resulting succinic acid molecules were derived from the initially captured CO2. Furthermore, they also completed scale-up experiments in 1-liter and 5-liter fermenters, successfully transitioning the research from laboratory shake flasks to pilot-scale production. Notably, the production of lactic acid as a product in this experiment also offers new possibilities for expanding the diversity of biodegradable plastics.
Based on the synthesized bioplastic monomers, the research team has further synthesized fully biodegradable PBS and PLA and produced demonstration straw products, demonstrating the industrial potential of converting seawater into green materials. The researchers explain that PBS and PLA are just demonstration cases of this biomanufacturing platform. Through modular design and combinatorial optimization of electrocatalytic and metabolic pathways, the platform is expected to be expanded to a diverse product portfolio, including organic acids, monomers, surfactants, and nutritional ingredients, serving industries such as materials, chemicals, pharmaceuticals, and food.
Looking ahead, the research team plans to construct integrated "green factories" in coastal areas. These factories will utilize electrocatalytic devices to continuously capture carbon dioxide from seawater and convert it into formic acid. Engineered bacteria in fermentation tanks will then efficiently convert the formic acid into green plastic raw materials. With continued optimization and large-scale application of the technology, this research will effectively mitigate seawater acidification and establish an integrated green industrial chain from "carbon capture to material production to finished products," truly realizing a sustainable production model of "capturing carbon while producing materials."
