Introduction

Atmospheric carbon dioxide (CO2) capture is crucial in addressing climate change. While potassium hydroxide (KOH) can effectively react with CO2, its use as a CO2 absorber is limited by several factors that make it less favorable compared to alternative materials.

Chemical Reaction and Efficiency

Despite its effectiveness, KOH reacts with CO2 to form potassium carbonate (K2CO3) and water. The resulting carbonate products must be carefully managed, and the large-scale efficiency of this process is a concern. Unlike other materials, KOH absorbs CO2 through a simple reaction, which may reduce the overall efficiency and scalability in real-world applications.

Cost and Availability

The production of KOH is relatively expensive, making it less cost-effective for large-scale CO2 capture. Other options such as sodium hydroxide (NaOH) and amine solutions are often preferred due to their lower costs and greater availability. When compared to other CO2 sequestration methods, KOH’s cost is a significant drawback.

Handling and Safety

KOH is a strong base that poses handling and safety challenges, especially in large-scale atmospheric CO2 capture systems. Its corrosive nature can cause significant safety concerns and complicate the implementation of such systems.

Regeneration Challenges

An ideal absorbent should be easily regenerable to achieve cost efficiency and sustainability. Regenerating KOH involves heating to decompose the carbonate, which can be energy-intensive and less straightforward compared to regenerating other sorbents like amines. This process adds to the overall cost and complexity of the CO2 capture system.

Environmental Impact

The production and use of KOH can have environmental impacts, including the generation of waste products. In contrast, more sustainable alternatives are often sought in carbon capture technologies. The environmental footprint of producing KOH is particularly significant, as it involves energy-intensive processes and can release CO2 during production.

Existing Technologies

Many established carbon capture technologies focus on other materials, such as amines, which have been extensively studied and optimized for efficiency. Amines are preferred in many applications due to their proven effectiveness and lower costs.

Production Challenges of KOH

The production of KOH is not without its challenges, especially in terms of carbon footprint. The calcination of potassium carbonate, a common method for producing KOH, releases CO2 on a molecular basis as each molecule of potassium hydroxide is produced. Additionally, the electricity required for the electrolysis of KCl brine in a variant of the chlor-alkali process also contributes to CO2 emissions.

Alternatives and Mineralization

Mineralization methods, such as serpentine, olivine, and rock forms, are proposed as more sustainable alternatives to KOH. These compounds have lower energy input requirements and can store CO2 more efficiently. Additionally, the potassium cation in KOH is highly desirable for many other applications, particularly as a plant fertilizer.

Electrochemical Production Method for KOH

Using electrochemical methods to produce KOH with renewable energy sources can help mitigate the carbon footprint of the production process. This method involves less energy-intensive processes and can be more sustainable compared to traditional methods. By ensuring that the production process does not significantly increase CO2 emissions, electrochemical production methods can be a viable option for CO2 absorption and storage.