The process of permanently storing plant-captured CO2 as SiC, a valuable material for electronics, has been quantified by Salk scientists. Plants have an unrivaled ability to absorb CO2 from the air, but this advantage is only temporary, as remaining crops return carbon into the environment, primarily through decomposition. Researchers have proposed a more permanent, and even useful, fate for this captured carbon by converting plants into a valuable industrial material known as silicon carbide (SiC), providing a strategy for converting an atmospheric greenhouse gas into a commercially and industrially valuable material.
Salk scientists turned tobacco and maize husks into SiC in a recent study published in the journal RSC Advances, and quantified the process in greater detail than ever before. These discoveries will aid researchers, such as those from Salk’s Harnessing Plants Initiative, in evaluating and quantifying carbon-sequestration solutions that could help ameliorate climate change as CO2 levels continue to climb to unprecedented levels.
Co-corresponding author and Salk Professor Joseph Noel tells SciTechDaily that the research goes into great detail about how you generate this precious chemical and how many atoms of carbon you’ve removed from the environment. With that amount, you may begin to infer what role plants could play in reducing greenhouse gas emissions while also transforming an industrial byproduct, CO2, into valuable commodities through natural processes such as photosynthesis.
SiC, commonly known as carborundum, is an ultrahard substance that is used in ceramics, sandpaper, semiconductors, and light-emitting diodes (LEDs). The Salk team employed a previously disclosed method to measure carbons at each phase of the transformation of plant material into SiC: To begin, the researchers started with seed tobacco, which was chosen for its short growing season. The gathered plants were then frozen and milled into a powder, which was subsequently treated with a variety of chemicals, including a silicon-containing substance. The powdered plants were petrified and hardened to generate SiC in the third and final stage, which involved heating the material to 1600 °C.
“The rewarding part was that we were able to demonstrate how much carbon can be sequestered from agricultural waste products like corn husks while producing a valuable, green material typically produced from fossil fuels,” according to Suzanne Thomas, a Salk staff researcher and first author of the publication.
The authors observed a 50,000-fold increase in sequestered carbon from seed to lab-grown plant using elemental analysis of the plant powders, confirming plants’ effectiveness at removing atmospheric carbon. When plant material is heated to high temperatures for petrification, some carbon is lost as a variety of breakdown products, but around 14% of the carbon is retained. The researchers found that producing 1.8 g of SiC took roughly 177 kW/h of energy, with the furnace in the petrification step using the majority of that energy (70 percent). The authors point out that contemporary SiC production technologies have similar energy costs. While the plant-to-SiC method isn’t carbon-neutral due to the energy required for production, the team believes that future technologies developed by renewable energy businesses could reduce energy prices.
The team plans to investigate this method further with a broader range of plants, particularly those that naturally contain substantial levels of silicon, such as horsetail or bamboo. James La Clair, a visiting professor at Salk Institute, reports to Salk Institute’s own news page “This is a step towards making SiC in an environmentally responsible approach.”