Strategy  for  Climate Crisis: Introducing Innovative System for CO<sub>2</sub> Fixation and Storage

Kenji Sorimachi; Toshinori Tsukada; Wataru Kobayashi; Hossam Gabbar

doi:10.37871/jbres1774

ISSN: 2766-2276

Environmental Sciences . 2023 June 30;4(6):1108-1112. doi: 10.37871/jbres1774.

Subject area(s)

Environmental Impacts

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Short Communication

Strategy for Climate Crisis: Introducing Innovative System for CO₂ Fixation and Storage

Kenji Sorimachi^1*, Toshinori Tsukada², Wataru Kobayashi³ and Hossam Gabbar⁴

¹Bioscience Laboratory, Environmental Engineering, Co., Ltd., Takasaki, Gunma, Japan
²KSI, Takasaki, Gunma, Japan
³Environmental Engineering Institute, Inc., Annaka, Gunma, Japan
⁴Department of Energy and Nuclear Engineering, Faculty of Engineering and Applied Science, Ontario Tech University, Canada

*Corresponding author: Kenji Sorimachi, Bioscience Laboratory, Environmental Engineering, Co., Ltd., Takasaki, Gunma 370-0041, Japan E-mail:

Received: 20 June 2023 | Accepted: 29 June 2023 | Published: 30 June 2023

How to cite this article: Sorimachi K, Tsukada T, Kobayashi W, Gabbar H. Strategy for Climate Crisis: Introducing Innovative System for CO₂ Fixation and Storage. 2023 June 30; 4(6): 1108-1112. doi: 10.37871/jbres1757, Article ID: jbres1757

Keywords

CO₂ fixation
CO₂ storage
Climate change
H2 generation
NaCl electrolysis
CaCO3
Limestone
Direct Air Capture (DAC)

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Abstract

The so-called Paris Agreement was reached at the United Nations Climate Change Conference (COP20) in 2015. This agreement was based on the requirement to keep the increase in the mean global temperature below 2°C relative to the temperature prior to the industrial revolution, and preferably less than 1.5°C. At present, this goal is challenging based solely on the development of carbon-neutral energy systems. The concept of the carbon-neutral society by 2050 seems to be far too late. Herein, we propose an innovative system based on simple chemical reactions using NaOH and CaCl₂ via the electrolysis of NaCl or seawater. The generated H2 from the electrolysis of NaCl can be used as a clean energy source for fuel batteries, supplying electricity for the operation of the system. When other renewable energy sources power the system, H2 can be generated as a clean energy alternative. Furthermore, this system produces stable and harmless CaCO3 as a final product, along with NaCl, which can be reused as an electrolysis starting material. The proposed system provides a safe and inexpensive approach for simultaneous CO₂ fixation and storage.

Introduction

The Intergovernmental Panel on Climate Change (IPCC) concluded on August 9th, 2021, that climate change has been caused by human activities that have produced carbon dioxide (CO₂) since the industrial evolution [1]. A few days ago, in early June 2023, Japanese mass media, including television, announced severe mega mountain fires in Canada. The smoke from these fires covered New York City, creating an apocalyptic scene reminiscent of the end of the century. Surprisingly, some smoke even reached Washington D.C., USA, despite the considerable distance from the source. According to reports, the fires in Canada were believed to have been sparked by lightning strikes, with multiple locations being affected owing to climate change. In addition, other natural phenomena have recently increased, such as heavy rains, torrential rains, super hurricanes, super tornadoes, glacier retreats, and the expansion of desert areas.

The planet may be nearing a threshold beyond which unpredictable environmental change may occur, such as increase in the mean global temperature [2]. However, we have not paid a little attention to the effect of increase in atmospheric CO₂ concentration for a long time. One of reasons is due to our wide tolerance toward CO₂ concentration in daily life. In fact, the atmospheric CO₂ concentration at the house room is about 400 ppm, while the concentration easily reaches twice in the presence of several person for certain times in the same room without ventilation. Even under high CO₂ concentration around 1,000 ppm for certain time in the limited space, our life doesn’t feel an abnormal symptom. Eventually, many people would be apparently insensitive to a small increase in atmospheric CO₂ concentration, although this small change clearly induced climate change crisis on the earth. Our wide tolerance toward CO₂ concentration is due to CO₂ characteristics that CO₂ doesn’t bind with biological compounds such as amines is easily excluded by the lung tissues based on concentration gradient force, like a "pseudo-osmosis" [3]. In order to resist the highly produced CO₂, organisms including human beings have acquired the insensitivity to CO₂ to adapt to environment during biological evolution. In mitochondrial evolution, active species have more evolved than less active species [4]. This respiratory function based on CO₂ characteristics was acquired by organisms during biological evolution [5]. Eventually, the most evolved human beings have induced climate crisis due to consumption of fossil fuel.

Although there are several methods for CO₂ capture, such as absorption [6-12] and membrane gas separation [3,13-18], only amines have been currently used [19,20]. However, this organic solvent method for CO₂ fixation is limited owing to the decomposition of amines during the heat treatment for CO₂ liberation from the amine-CO₂ complex. In addition, the amine degradation needs regeneration for further use. In contrast, we developed an innovative method for CO₂ fixation and storage using NaOH and CaCl₂ [21]. This method converts CO₂ from the ambient atmosphere or exhaust gas into CaCO₃, a natural, harmless, and stable component in limestone or coral.

2NaOH + CO₂ → Na2CO3 + H₂O

Na₂CO₃ + CaCl₂ → CaCO₃ + 2NaCl

At high NaOH concentrations, > 0.2 M, NaOH and CaCl₂ formed Ca(OH)2 and NaCl in the absence of CO₂ [21]. To enhance the reaction efficiency of CO₂ with NaOH solution, the NaOH solution was formed as a mist inside the reaction chamber [22], or CO₂ was bubbled into the NaOH solution [23].

We recently proposed an integrated CO₂ fixation system, as shown in figure 1. The system consists of four units. Unit I represent an electrolysis chamber where NaCl or seawater is converted to NaOH in the cathode region and HCl in the anode region. Simultaneously, H₂ is generated with NaOH, and some of the generated H₂ can be supplied to a fuel battery for electricity generation. Another part of the generated H₂ can be used as a clean energy source. If sufficient external electricity is supplied renewable energy sources, such as solar plane and wind power, or from other energy sources, such as thermal and nuclear power, a large amount of H2 can be generated as a clean energy source.

Unit II represents the CO₂ reaction chamber, where CO₂ reacts with the OH− formed from NaOH. In this unit, mist formation [22] or CO₂ bubbling [23] in the NaOH solution increases the reaction efficiency by expanding the surface area. In addition, increasing the volume of the reaction chamber enhances CO₂ fixation efficiency. The mist formation technique of NaOH solution is suitable for direct air capture, which treats an extremely large volume of air [22], while the method involving CO₂ bubbling is well-suited for fixing high concentrations of CO₂ [23].

Unit III represents the CO₂ liberation chamber, where Na2CO3 is converted into NaCl and CO₂ by adding HCl, produced in unit I [20]. The acidification of Na2CO3 releases CO₂ and NaCl, while the CO₂–ethanol amine complex releases CO₂ and ethanol amine [20]. This unit can produce concentrated pure CO₂ from the ambient air, which can be used as a starting material for methanation [24]. For CO₂ storage, geo-sequestration by injecting CO₂ into underground geological formations, such as oil fields, gas fields, and saline formations, has been suggested [25,26], although these systems are still projects for future. Na2CO3 is produced via the Solvay method and used as a material in the glass industry. Furthermore, this compound mimics insulin in glucose consumption in cultured cells [27,28]. Additionally, amines also mimic insulin in glucose consumption not only in vitro but also in vivo [29].

Unit IV represents the CaCO3 formation chamber in the presence of CaCl₂ [21]. Seawater can be used instead of CaCl₂, although it is advisable to concentrate it before use because of its low concentration. A reverse osmotic membrane is beneficial to concentrate seawater salts, and simple seawater evaporation applies to concentrate. As the precipitate of CaCO3 is heavy, the decantation is applied to separate CaCO3 from the solution. This method is a more inexpensive alternative to filtration. Each unit can be integrated into one unit, while each can be divided into multiple units for different purposes.

As mentioned earlier, the accumulated CO₂ in the Earth’s atmosphere has induced the present climate change (Figure 2). Gradual reduction of atmospheric CO₂ levels would considerably improve the present climate change situation. However, even if a carbon-neutral society with zero CO₂ emission would be achieved at present, the present climate change could not be improved permanently because of the persistent CO₂ concentration. In contrast, if carbon emission continues in future, the CO₂ concentration in the atmosphere will increase, exacerbating the climate crisis. This scenario would have detrimental effects on both humans and other organisms on the Earth. We comprehend this fundamental theory and select a course of action that effectively reduces the accumulated CO₂ in the atmosphere for future generations and a beautiful blue planet.

Conclusion

In order to improve the present climate changes, there is no method other than CO₂ reduction from the ambient atmosphere immediately. In addition, the introduced system based on NaCl electrolysis and chemical reaction of NaOH and CaCl₂ provides a safe, inexpensive approach to simultaneous CO₂ fixation and storage. Thus, the introduced system demonstrated a simple approach to fit worldwide usage without environmental concerns.