Combating climate change: Scientists develop efficient, greener way to capture CO2, convert into SiC

Due to the alarming issue of climate change over the past decades, scientists from the Salk Institute of Biological Studies in San Diego, California have developed an artificial carbon cycle for agricultural plants to more efficiently sequester atmospheric carbon dioxide (CO2) and eventually provide a greener approach to convert it into silicon carbide (SiC), a valuable industrial material.

Artificial and natural carbon cycles. Source: Plant-based CO2 drawdown and storage as SiC, RSC Adv., 2021, 11, 15512

Naturally, Earth regulates atmospheric CO2 through carbon cycles occurring in terrestrial, coastal and deep marine environments. However, anthropogenic activities such as large-scale industrial development and burning of fossil fuels have resulted in the exponential increase of greenhouse gas levels in the atmosphere, making it difficult to be mitigated alone by natural carbon cycles.

On the other hand, SiC production is seeing a large market growth due to the compound’s promising properties such as extreme strength and thermal stability, making it valuable for a wide array of industries. SiC is rare in nature so it has to be synthetically produced using petroleum coke (petcoke). However, this method allows a great amount of carbon contained in petcoke to be released into the atmosphere as CO2, further contributing to greenhouse gas pollution.

A research team from the Salk Institute hence suggested through a study to employ an artificial yet more permanent way to increase CO2 capture potential by petrifying plant biomass while being able to synthesize SiC from these petrified products.

With the use of Nicotiana tabacum, a short-lived tobacco plant, which was grown in modified laboratory settings, the amount of carbon content from seed to fully-grown plant was quantified through elemental analysis. The plant was found to have sequestered carbon by a 50,000-fold increase as compared to plants grown in standard conditions, demonstrating the vital role of plants in capturing atmospheric CO2 when utilized properly.

Along with the lab-grown tobacco plants, cornhusks were obtained from markets to be petrified. Eventually, agricultural waste products such as cornhusks release back the captured carbon into the atmosphere through decomposition. With experimentally petrified tobacco and cornhusks, plants were observed to retain 14% of captured carbon and eventually convert it into SiC-containing products.

Despite the large amount of energy needed to produce SiC (approximately 177 kW/h per 1.8 g of SiC) by the petrification of plant biomass, the research poses hope in mitigating greenhouse gas pollution.

"This is a step towards making SiC in an environmentally responsible approach," says author and Salk Institute scientist James La Clair.

The article was published last April 27, 2021 in the RSC Advances journal. The research team further expressed hope to expand the study on other plant varieties to positively contribute to the issue of climate change by developing processes for enhanced CO2 capture and greener SiC manufacturing.

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References

Thomas, S. T., Shin, Y. S., La Clair,J. J. & Noel, J. P. (2021). Plant-based CO2 drawdown and storage as SiC. RSC Advances, 2021; 11 (26): 1551. doi: 10.1039/d1ra00954k

Science Daily (2021, May 6). Transforming atmospheric carbon into industrially useful materials. Retrieved 13 May 2021 from https://www.sciencedaily.com/releases/2021/05/210506163626.htm?fbclid=IwAR1P1iWm-YlejFkBk7rei4jMS5bhgdKAi4nFUoAn_zs_m0HNY7zDWS5IAp4