The Future of Ocean Carbon Capture

A Project By Arav Mathur, Shaurya Pratap Singh, Sushmit Chakma, and Prabhnoor Dhaliwal.

Amid the global environmental crisis, one of the gravest challenges we face is the alarming phenomenon known as ocean acidification. As carbon dioxide emissions continue to rise, a significant portion of this greenhouse gas is absorbed by our oceans, triggering a relentless acidifying process. The consequences are far-reaching, jeopardizing marine ecosystems and the delicate balance of life within them, and the solution is combating carbon.

Carbon Capture Tech — Done the right way…

In an era defined by the urgent need for climate action, scientists and researchers have been tirelessly exploring innovative approaches to combat the escalating carbon dioxide crisis. One such breakthrough has emerged — a revolutionary method for removing carbon dioxide from ocean water. This game-changing technique harnesses the power of electrochemical systems, introducing bismuth and silver electrodes into the equation. By capturing and releasing chloride ions in a spatially separated yet electrically connected environment, this method paves the way for a chloride-mediated electrochemical pH swing and do carbon capture efficiently better than the current methods.

Okay! Let’s not get too confused. The basic idea is to use two silver-bismuth systems operating in tandem in a cyclic process. One system would acidify the ocean water, and the other would regenerate the electrodes by alkalizing the treated stream. This would allow CO2 to be continuously removed from simulated ocean water with a relatively low energy consumption of 122 kJ mol−1, without relying on expensive bipolar membranes.

Now, Let us delve into the intricacies of this remarkable system and explore how it operates in tandem, transforming simulated ocean water into a reservoir of hope for a sustainable future.

The method described for removing carbon dioxide from ocean water involves using an electrochemical (consisting of two or more electrodes spatially separated while also being in electrical contact with one another via a separate current path) system with bismuth and silver electrodes that can capture and release chloride ions. The difference in reaction stoichiometry between the two electrodes enables an electrochemical system architecture for a chloride-mediated electrochemical pH swing, which can be leveraged to remove CO2 from ocean water without costly bipolar membranes effectively.

The basic idea is to use two silver-bismuth systems operating in tandem in a cyclic process. One system would acidify the ocean water, and the other would regenerate the electrodes by alkalizing the treated stream. This would allow CO2 to be continuously removed from simulated ocean water with a relatively low energy consumption of 122 kJ mol−1, and high electron efficiency.

Now, to understand the design of the carbon capture system, it is important first to understand the electrochemical process being used. The process involves the use of bismuth and silver electrodes, which can capture and release chloride ions. When an electric current is applied to the system, chloride ions are oxidized at the anode (positive electrode), releasing electrons and forming chlorine gas. Meanwhile, chloride ions are reduced at the cathode (negative electrode), consuming electrons and forming hydrogen gas.

The difference in the reaction stoichiometry between the two electrodes creates a pH swing, which is the key to the system’s effectiveness. When chlorine gas is produced at the anode, it reacts with water to form hypochlorous acid and chloride ions. The hypochlorous acid dissociates into hydrogen and hypochlorite ions, lowering the system’s pH. Conversely, hydrogen ions are consumed at the cathode to produce hydrogen gas, which raises the system’s pH.

The system can maintain a consistent pH swing by alternating the anode and cathode in a cyclic process. In the case of the carbon capture system, one silver-bismuth system would be used to acidify the ocean water, causing it to release carbon dioxide. The other system would then be used to alkalize the treated stream, regenerating the electrodes and producing hydrogen gas.

The carbon capture system would need to be robust enough to withstand the harsh ocean environment and operate autonomously for extended periods. It would also need to be scalable, with the ability to capture significant amounts of carbon dioxide. The system would require a power source, likely solar panels or batteries, to provide the energy needed for the electrochemical reactions.

Design & Details

1. Electrode design: The electrochemical system will consist of bismuth and silver electrodes. The electrodes will maximize the surface area in contact with the seawater, enhancing the capture and release of chloride ions. The electrodes will be made of high-quality bismuth and silver materials to ensure durability and longevity.
2. Electrolyte: The electrolyte will be sodium chloride (NaCl) solution dissolved in water, acting as a source of chloride ions. This will allow the chloride-mediated electrochemical pH swing to occur.
3. Two-cell design: The electrochemical system will consist of two cells. The first cell will acidify the seawater by capturing the CO2 and releasing hydrogen ions (H+) into the solution, lowering the pH. The second cell will regenerate the electrodes by releasing the captured CO2 and hydroxide ions (OH-) into the solution, raising the pH.
4. Cyclic process: The two cells will operate in tandem in a cyclic process. In the first cell, the bismuth electrode will capture chloride ions and release hydrogen ions, lowering the seawater’s pH and increasing the concentration of dissolved CO2. The silver electrode in the first cell will release chloride ions and capture hydrogen ions, which will regenerate the electrode. In the second cell, the bismuth electrode releases chloride ions and captures hydroxide ions, raising the seawater’s pH and releasing the captured CO2. The silver electrode in the second cell will capture chloride ions and release hydroxide ions, regenerating the electrode.
5. Energy consumption: The electrochemical system will have a relatively low energy consumption of 122 kJ mol−1, making it more cost-effective than other carbon capture methods.
6. Material: The robot will be made up of materials that can withstand the harsh conditions of the ocean, such as corrosion-resistant metals and high-quality plastics.

Overall, the electrochemical system with bismuth and silver electrodes will use a cyclic process to capture and release CO2 from seawater using an electrolyte solution of sodium chloride. The two-cell design will allow for the continuous removal of CO2 from the seawater with a low energy consumption, making it a promising solution for reducing the concentration of CO2 in the atmosphere.

Deeper into Tech

To incorporate robots into the carbon capture process, the design would need to include a system for deploying and controlling the electrochemical system in the ocean. This could involve using autonomous underwater vehicles (AUVs) or remotely operated vehicles (ROVs) to transport and operate the electrochemical system.

The AUV or ROV would need to be equipped with the electrochemical system and the necessary sensors and control systems to monitor and adjust the system’s operation. The AUV or ROV could be programmed to autonomously navigate to the target area, deploy the system, and initiate the carbon capture process.

Alternatively, a hybrid system could be used, where the AUV or ROV would transport the electrochemical system to the target location. Then a remote operator would take control of the system to initiate and monitor the carbon capture process.

In either case, the robotic aspect of the carbon capture process would involve the design of an AUV or ROV with the necessary capabilities to deploy and operate the electrochemical system in the ocean. This would require expertise in robotics, control systems, and underwater engineering.

Thus, the combination of the asymmetric chloride-mediated electrochemical process with bismuth and silver electrodes and the use of autonomous underwater vehicles or remotely operated vehicles could provide a promising approach for carbon capture from the ocean, with the potential to help mitigate the impacts of climate change.

The Silver-Bismuth Systems & Chemistry Behind the Idea

The system’s key components are the two silver-bismuth systems mentioned in the asymmetric chloride-mediated electrochemical process for CO2 removal from ocean water. These systems work in tandem in a cyclic process to effectively remove CO2 from ocean water.

Each system consists of a bismuth electrode and a silver electrode. The bismuth electrode acts as the anode, while the silver electrode acts as the cathode. When a voltage is applied across the electrodes, chloride ions in the water are oxidized at the anode, releasing electrons and producing chlorine gas:

2Cl- → Cl2 + 2e-

Meanwhile, at the cathode, water is reduced to hydroxide ions and hydrogen gas:

2H2O + 2e- → H2 + 2OH-

The hydroxide ions produced at the cathode then react with the CO2 in the water to form bicarbonate ions:

CO2 + H2O + OH- → HCO3-

This process effectively removes CO2 from the water, storing the bicarbonate ions in a separate tank for later use.

After a certain amount of time, the electrodes become coated with chloride and hydroxide ions, which inhibits their ability to react with the water. To regenerate the electrodes, the two systems switch roles. The silver electrode in the first system becomes the anode, while the bismuth electrode in the second system becomes the cathode. The treated water is then passed through the second system, which regenerates the electrodes through alkalization of the treated stream.

The robot carrying out this process would likely be made of materials such as stainless steel or titanium, which are resistant to corrosion and can withstand the harsh oceanic environment. The design of the robot would need to incorporate the necessary electrodes and tanks for storing the bicarbonate ions and regenerating the electrodes.

In short, using two silver-bismuth systems in this process allows for efficient and effective removal of CO2 from ocean water, with relatively low energy consumption.

Robot tech specs

The first step in the process would be to design an autonomous underwater vehicle (AUV) or remotely operated vehicle (ROV) capable of carrying the electrochemical system to the target location. This would require an underwater robot able to move through the water and navigate to a specific location. The robot would also need to be able to carry the electrochemical system, which includes the bismuth and silver electrodes, as well as the necessary sensors and control systems to monitor and adjust the system’s operation.

Once the robot arrives at the target location, it must deploy the electrochemical system into the ocean. This could involve the use of robotic arms or other mechanisms to position the electrodes in the water. The robot would also need to ensure that the electrochemical system is secured in place to prevent it from drifting away.

Once the electrochemical system is in place, the robot must initiate the carbon capture process. This involves the cyclic process of acidifying and alkalizing ocean water using the two silver-bismuth systems. The robot must ensure that the electrochemical system is operating correctly and that the acidification and alkalization processes are occurring at the appropriate times.

The robot would also need to monitor the concentration of CO2 in the water to determine when the electrochemical system has captured enough CO2. This would require sensors capable of measuring the CO2 concentration in the water. Once the desired amount of CO2 has been captured, the robot would need to retrieve the electrochemical system and transport it back to the surface for processing.

To summarize, the robot’s function in the carbon capture technology would involve deploying, operating, and monitoring the electrochemical system in the ocean. This would require a sophisticated underwater robot with the ability to navigate, carry equipment, and operate the electrochemical system to capture CO2 from the ocean.

Workings & Movements of Robots

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1. Movement: The robots could use various methods to move through the water, including propellers, thrusters, or even fins for more efficient swimming. They could also use GPS or other navigation technologies to move to specific areas of the ocean.
2. Sensors: The robots would be equipped with various sensors to monitor the surrounding environment, including temperature, salinity, pH levels, and CO2 concentrations. These sensors would provide real-time data that would be used to adjust the operation of the carbon capture system.
3. Carbon capture system: The carbon capture system would consist of an electrochemical cell with bismuth and silver electrodes, as described earlier. The system would be housed in a container on the floating robot, designed to withstand the harsh conditions of the ocean environment.
4. Power: The robots would require a power source to operate, which could come from various sources, including solar panels, batteries, or even wave or tidal power.
5. Communication: The robots could be equipped with communication technologies, such as satellite or radio communication, to transmit data back to shore and receive instructions for operation.

Therefore, these floating robots would be a more effective and efficient solution for ocean carbon capture than current methods, such as large-scale industrial systems or ocean fertilization. The robots would be able to operate in remote areas of the ocean, where traditional systems are not feasible, and would be more cost-effective and less energy-intensive. Additionally, the real-time data provided by the sensors would allow for more precise monitoring and adjustment of the carbon capture system, leading to more efficient operation and a higher rate of CO2 removal.

How is it Better from What’s Been Happening

Compared to the current methods for addressing ocean acidification, the proposed electrochemical system with bismuth and silver electrodes offers several advantages.

Photo by Carl Heyerdahl on Unsplash

1. The traditional methods of addressing ocean acidification, such as reducing carbon emissions and promoting the growth of seaweed forests, have proven insufficient to curb the effects of ocean acidification. According to the National Oceanic and Atmospheric Administration (NOAA), ocean acidification is happening at a rate faster than any time in the past 300 million years. The current rate of ocean acidification is causing serious harm to marine life and ecosystems, with shell-forming organisms such as oysters and clams being particularly vulnerable.
2. The proposed electrochemical system can remove CO2 from seawater with relatively low energy consumption and high electron efficiency. The system requires only 122 kJ mol−1, which is significantly lower than other carbon capture and storage technologies. This means that the proposed system could be more cost-effective than other methods of addressing the ocean.
3. In terms of specific numbers, the proposed system’s energy efficiency of 122 kJ mol−1 compares favorably to other carbon capture technologies that typically require 250–350 kJ mol−1. Additionally, the system’s scalability makes it a versatile solution for addressing ocean acidification on a wide scale.

Electrochemical System for Carbon Dioxide Removal from Ocean Water

Carbon dioxide (CO2) emissions from human activities are the main drivers of climate change. The oceans have absorbed significant CO2, leading to ocean acidification and impacting marine ecosystems. Removing CO2 from ocean water has been a topic of interest for researchers and engineers for many years.

System Architecture

In the case of the carbon capture system for ocean water, one silver-bismuth system would be used to acidify the ocean water, causing it to release carbon dioxide. The other system would then be used to alkalize the treated stream, regenerating the electrodes and producing hydrogen gas.

The carbon capture system would need to be designed to withstand the harsh ocean environment and be able to operate autonomously for extended periods. It would also need to be scalable, with the ability to capture significant amounts of carbon dioxide. The system would require a power source, likely solar panels or batteries, to provide the energy needed for the electrochemical reactions.

Advantages of the System

The electrochemical system for carbon dioxide removal from ocean water has several advantages over other carbon capture technologies. It does not require costly bipolar membranes, which can be expensive and difficult to maintain. The system has a relatively low energy consumption of 122 kJ mol−1 and high electron efficiency, making it more energy-efficient than other carbon capture technologies.

The system is also scalable and can capture significant amounts of carbon dioxide. The system can operate autonomously for extended periods, making it ideal for use in remote locations. It is also environmentally friendly, as it does not generate any harmful by-products.

Challenges and Future Research Directions

While the electrochemical system for carbon dioxide removal from ocean water has several advantages, some challenges must be addressed. One of the main challenges is the durability of the electrodes in the harsh ocean environment. The system must be designed to withstand the corrosive effects of saltwater and marine organisms.

Another challenge is the scalability of the system. While the system is effective in simulated ocean water, it is unclear how well it would perform in actual ocean conditions. Further research is needed to determine the feasibility of scaling up the system to capture significant amounts of carbon dioxide. The cost of the system is also a major challenge, and it is important to optimize the system design and materials to reduce costs and increase efficiency.

Future Directions

Photo by 🇸🇮 Janko Ferlič on Unsplash

Future research should focus on optimizing the system design and materials to improve efficiency and reduce the cost of the carbon capture system. The durability of the electrodes in the harsh ocean environment should also be further investigated to ensure the system’s long-term viability.

In addition, further research is needed to determine the feasibility of scaling up the system to capture significant amounts of carbon dioxide. This research should include studies of the system’s performance in actual ocean conditions and the development of robust and reliable monitoring systems to ensure the system’s proper functioning.

Mathematical Model

The electrochemical process in the carbon capture system can be described using mathematical models. The models can be used to optimize the system design and predict the system’s performance under different operating conditions.

The electrochemical process involves the transfer of electrons and ions across the electrode-electrolyte interface. The Butler-Volmer equation describes the transfer of electrons, which relates the electrode potential to the exchange current density and the concentration of reactants and products at the electrode surface.

The transfer of ions is described by the Nernst-Planck equation, which relates the flux of ions to the concentration gradient and the diffusion coefficient. The Nernst-Planck equation can be used to predict the transport of chloride ions in the carbon capture system.

The optimization of the carbon capture system involves the identification of the optimal system design and operating conditions. The system design should be optimized to maximize the capture efficiency and minimize the cost of the system. The operating conditions should be optimized to ensure the stability and longevity of the system.

The optimization of the system design involves the selection of materials and the configuration of the electrode and cell geometry. The materials should be selected based on their electrochemical properties and durability in the harsh ocean environment. The electrode and cell geometry should be configured to maximize the surface area and minimize the distance between the electrodes.

The optimization of the operating conditions involves the control of the pH, temperature, and flow rate of the electrolyte. The pH should be controlled to maintain the optimal pH swing for CO2 removal. The temperature should be controlled to ensure the stability of the electrodes and the electrolyte. The flow rate should be controlled to ensure the optimal transport of ions and the removal of CO2.

Conclusion

In conclusion, the electrochemical system for carbon dioxide removal from ocean water has the potential to be a game-changing technology in the fight against climate change. The system leverages the electrochemical process to remove CO2 from seawater in a scalable and energy-efficient manner. The system still faces several challenges, including the durability of the electrodes in the harsh ocean environment and the system’s scalability. However, with further research and development, the electrochemical system for carbon dioxide removal from ocean water could become a key technology in the fight against climate change.