The World Meteorological Organization reports that the levels of greenhouse gas in the atmosphere have increased like never before.
Massive growth in carbon dioxide (CO2) levels in 2020 exceeded the 10-year average, despite a 5.6% decrease in fossil fuel CO2 emissions due to COVID-19 restrictions. The continuous increase in CO2 concentrations is directly associated with the heavy usage of fossil fuels.
A recent study published in the KeAi journal Green Energy & Environment reports a novel method to capture CO2 using sunlight as the energy source and modified sawdust as the material that absorbs CO2. The study was performed by a research team from the Renmin University of China.
Besides trapping CO2, their approach prevents the use of fossil fuels, which would produce additional CO2. Crucially, the new absorption method is reversible, which enables the captured CO2 to be used to produce other products like methane, ethanol and methanol.
While a large number of high-performing CO2 absorbents have been developed in recent decades, people rarely pay attention to the carbon emitted by the adsorbent during its preparation. Moreover, typical industrial CO2 capture systems show high-energy consumption during the absorber regeneration process.
Yapei Wang, Study Corresponding Author and Professor, Department of Chemistry, Renmin University of China
“To solve these issues, we focused on a solution that not only fabricates low-energy consumption CO2 absorbents, it also uses sunlight as the single energy input to regenerate those absorbents,” she added.
The researchers discovered that sawdust infused with an aqueous solution of an amine-based polymer acted as a simplified CO2 absorbent with two significant benefits: it avoids the need for complex synthesis, can capture CO2 and can be regenerated by heating properly. Furthermore, a reflector and sunlight absorption layer helped to develop the sunlight harvesting systems, which heated the modified sawdust for capturing CO2.
Shiming Zhang, a Ph.D. student who was part of this study, says, “we were inspired by solar water heaters. Using sunlight as an energy input minimizes the need for traditional energy and is more environmentally-friendly.” According to Postgraduate Qianhao Pan, who was also a part of the research, “We believe less is more, sometimes a simple preparation process can lead to an effective solution that protects the environment.”
Zhang, S., et al. (2021) Sunlight-controlled CO2 separation resulting from a biomass-based CO2 absorber. Green Energy & Environment. doi.org/10.1016/j.gee.2021.09.001.