Sawdust shows great potential for capturing carbon

Last year, COVID-19 restrictions drove a 5.6 percent decrease in fossil fuel consumption. Despite this, the average growth in carbon emissions were higher than average over the last decade. 

Greenhouse gases, including CO2, have reached record highs across the globe. To address this problem, scientists have long been developing ways to capture carbon from the atmosphere. Some of these methods have required large amounts of energy or indeed create carbon themselves, making them impractical. 

Now, a study published in the journal Green Energy & Environment has demonstrated a simple new method for carbon capture developed by scientists at China’s Renmin University. The CO2 capture system uses modified sawdust as a CO2 absorbent powered only by sunlight. 

“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,” said study co-author Professor Yapei Wang. 

“Moreover, typical  industrial CO2 capture systems show high-energy consumption during the absorber regeneration process. 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.”

An important aspect of this method is that it’s also reversible. This means that carbon captured using the system could then be used to create other fuel products such as ethanol, methanol and methane. We can imagine this as a way of recycling fuel carbon emissions. 

Furthermore, the carbon capture system is quite simple and requires little energy input. Sawdust is soaked in a solution of amine based polymer. The sawdust is energized to absorb carbon with sunlight reflectors. 

Study lead author Shiming Zhang said the team was inspired by solar water heaters. “Using sunlight as an energy input minimizes the need for traditional energy and is more environmentally-friendly.”

“In summary, a non-fossil energy-consuming method possessing advantages of high scalability and elegant simplicity was exploited to prepare CO2 absorbents with the ability of reversible CO2 capturing and releasing,” concluded the study authors. 

“Serving as the supporting matrix, sawdust as a byproduct during the lumbering has been recognized as particularly new in the success of accommodating PEI polymers.” 

“The whole preparation process did not involve aggressive solvents or lengthy laboratory synthesis, affording great promise for the inexpensive and quick preparation of CO2 capture systems.”

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By Zach Fitzner, Earth.com Staff Writer