Mantel Capture, an American tech startup founded in 2022, has developed an innovative carbon dioxide (CO₂) capture system that captures CO₂ from industrial flue gas while storing thermochemical energy. This is achieved by using molten borate salts. The company aims to efficiently capture up to 95% of carbon emissions from smokestacks, offering a cost-effective solution for reducing emissions in hard-to-abate industries.
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Challenges: carbon capture
Industrial activities play a significant role in the United States' greenhouse gas emissions, accounting for 30% of direct emissions and ranking as the third-largest contributor. The majority of these emissions, approximately 70%, stem from the on-site combustion of fossil fuels, while the remainder comes from industrial processes, equipment leaks, and indirect emissions from electricity consumption.
Several energy-intensive industries bear the brunt of responsibility for industrial CO₂ emissions, including chemical manufacturing, petroleum refining, cement production, iron and steel manufacturing, and glass production. These industries often rely on high-temperature processes and substantial thermal energy requirements, contributing to their considerable carbon footprint.
Historically, CO₂ generated from industrial processes was released directly into the atmosphere. However, as awareness of climate change has grown, there has been a shift towards capturing and utilizing this CO₂.
Carbon capture and storage (CCS) technologies are being developed and implemented to reduce industrial emissions. These technologies involve capturing CO₂ at the source, compressing it, and transporting it to a storage location, typically underground. Meanwhile, captured CO₂ can be converted into valuable products by emerging innovative processes, such as hydrogenation processes, electrochemical reduction, and biological conversion.
Mantel Capture Technology
Mantel Capture (Mantel) has developed an innovative high-temperature molten salt-based carbon capture system, which integrates carbon capture process with thermochemical energy storage. It operates by continuously extracting CO₂ from industrial flue gas while simultaneously managing thermochemical energy. The system can store excess thermochemical energy during periods of low demand and release it when needed. This dynamic approach significantly enhances the system's overall efficiency and practical utility in industrial settings.
Mantel's technology addresses two critical challenges faced by energy-intensive industries: reducing carbon emissions and optimizing energy use. This integrated approach not only helps industries lower their carbon footprint but also potentially improves their energy efficiency and cost-effectiveness.
How Mantel captures CO₂
The diagram below depicts Mantel’s CO₂ capture process that utilizes high-temperature molten salt technology to efficiently remove carbon dioxide from industrial emissions. The process consists of two main stages: absorption and desorption, each occurring in separate reactors.
In the absorber reactor, which operates at temperatures between 500-700 ºC, CO₂-rich industrial flue gas is introduced. The reactor contains a molten borate salt, typically (Li₀.₅Na₀.₅)₃BO₃, which serves as the CO₂ capture agent. As the flue gas contacts the molten salt, an exothermic chemical reaction occurs:
(Li₀.₅Na₀₅)₃BO₃ + CO₂ → (Li₀.₅Na₀₅)BO₂ + (Li₀.₅Na₀₅)₂CO₃
This reaction generates heat, helping to maintain the reactor's high operating temperature. The resulting CO₂-lean gas can be safely emitted, while the CO₂-rich molten salts ((Li₀.₅Na₀₅)BO₂ and (Li₀.₅Na₀₅)₂CO₃) are transferred to the desorber reactor.
The desorber reactor operates at an even higher temperature range of 550-800 ºC. Here, the CO₂-rich molten salts undergo a reversible, endothermic reaction:
(Li₀.₅Na₀₅)BO₂ + (Li₀.₅Na₀₅)₂CO₃ → (Li₀.₅Na₀₅)₃BO₃ + CO₂
This reaction is endothermic. Therefore, the desorber reactor is electrically heated to maintain a higher operating temperature.
To maintain the necessary higher temperature, the desorber reactor is electrically heated. This process yields pure CO₂ and regenerates the borate salt capture agent (CO₂-lean molten salt), which is then recycled back to the absorber reactor for continued CO₂ capture.
The pure CO₂ produced by this process can be permanently sequestered underground or utilized in various innovative ways:
- Conversion into fuels, chemicals, and building materials
- Electrochemical reduction to produce chemicals like ethylene and methanol
- Biological transformation into biofuels and bioplastics using microorganisms
Mantel’s carbon capture process relies on a chemical reaction between the molten borate salt and CO₂. This reaction not only removes CO₂ from industrial emissions but also stores thermochemical energy, creating a synergistic effect that enhances the overall efficiency of the system and utility in industrial applications.
How Mantel integrates CO₂ capture with thermochemical energy storage
Mantel's carbon capture system uniquely combines CO₂ removal with thermochemical energy storage. This synergistic approach not only effectively captures CO₂ from industrial emissions but also enhances overall system efficiency and utility in industrial applications by managing thermal energy.
The diagram below depicts the integrated system of molten salt-based CO₂ capture with thermochemical energy storage.