Patcay.com – Across the globe, scientists are embarking on a quest to discover innovative methods for extracting carbon dioxide from the atmosphere or power plant emissions and converting it into a practical substance.
Among the most promising endeavors is the conversion of carbon dioxide into formate, a substance that exists in liquid or solid form, similar in utility to hydrogen or methanol, for use in powering fuel cells and generating electricity.
The process, developed by researchers at MIT and Harvard University, presents a significant breakthrough in addressing the limitations that have hampered previous conversion techniques.
Traditionally, carbon dioxide conversion processes involve a two-step approach: first, the gas is chemically captured and transformed into a solid form like calcium carbonate, followed by a subsequent heating phase to convert it into a usable fuel precursor, such as carbon monoxide.
This second step typically exhibits low efficiency, converting less than 20 percent of gaseous carbon dioxide into the desired product.
In contrast, the novel method achieves a conversion rate of well over 90 percent and eliminates the need for the inefficient heating step. It accomplishes this by initially transforming carbon dioxide into an intermediate form called liquid metal bicarbonate.
Subsequently, this liquid is electrochemically converted into liquid potassium or sodium formate using an electrolyzer powered by low-carbon electricity sources like nuclear, wind, or solar power.
The concentrated potassium or sodium formate solution can then be dried and stored in standard steel tanks for extended periods, offering stability and convenience for long-term use.
The researchers have overcome multiple challenges to optimize the process’s efficiency. They’ve designed the membrane materials and configuration to maintain a steady pH balance, ensuring continuous and stable conversion over extended durations.
The system demonstrated over 200 hours of operation without significant output decrease. Moreover, the use of an additional “buffer” layer of bicarbonate-enriched fiberglass wool effectively blocked unwanted side reactions, preventing the production of non-useful byproducts.
Furthermore, the team has developed a specialized fuel cell tailored for the utilization of formate fuel to generate electricity. The solid formate particles are easily dissolved in water and fed into the fuel cell when required.
While solid fuel may be heavier than pure hydrogen, the reduced weight and volume of high-pressure hydrogen gas storage tanks make the electricity output nearly equivalent in terms of storage volume.
The potential applications for formate fuel range from individual households to large-scale industrial or grid-based energy storage systems. Initial household setups could feature a refrigerator-sized electrolyzer to capture and convert carbon dioxide into formate, which could then be stored in underground or rooftop tanks. When needed, the solid powder could be mixed with water and utilized in a fuel cell to supply power and heat.
Ted Sargent, a professor of chemistry and electrical and computer engineering at Northwestern University, lauds the formate economy as a compelling concept, noting that metal formate salts are both benign and stable, making them a promising energy carrier. He highlights the enhanced efficiency of the liquid-to-liquid conversion from bicarbonate feedstock to formate and the successful use of these fuels for electricity production.