About This Project
Direct Air Capture (DAC) is recognized as the ‘gold standard’ for CO2 removal due to its durability and scalability. However, its widespread adoption has been hindered by high energy needs and limited availability of renewable energy. Geothermal energy, which provides both heat and electricity, offers a practical solution. This project will assess the impacts of Hydrogen Sulphide on DAC adsorbents, optimizing performance, thus paving the way for cost-effective deployment.
Ask the Scientists
Join The DiscussionWhat is the context of this research?
Integrating DAC with geothermal resources presents a promising and economically viable solution for large-scale carbon removal. In geothermal-rich regions like Kenya, this synergy provides significant advantages, including a reliable, low-carbon supply of electricity and heat to meet DAC’s high energy demands. Additionally, these regions rich in geothermal energy offer ideal geological conditions for CO2 sequestration, enabling a complete DAC and storage value chain. However, the high concentration of hydrogen sulfide (H2S) in geothermal fluids poses a challenge. This issue, which remains largely underexplored, is critical as H2S could affect the longevity and efficiency of DAC adsorbents, potentially impacting the scalability of the technology.
What is the significance of this project?
Hydrogen Sulphide (H2S), a common byproduct of geothermal energy, can significantly impact the efficiency of DAC adsorbents. Understanding these interactions is crucial to optimizing DAC adsorbents in H2S-rich environments which will unlock the full potential of DAC+ Geothermal integration. This research project aims to assess the immediate impact of H2S on adsorbents. If H2S incessantly ‘chokes’ and degrades the adsorbents, it could raise serious concerns about the feasibility of scaling critical tech like DAC in geothermal-rich regions. Consequently, this project will lay the groundwork for validating both the technical and economic feasibility of DAC-Geothermal systems, advancing clean energy solutions in Kenya and other regions with similar energy challenges within the DAC scope.
What are the goals of the project?
The project will focus on using a breakthrough reactor fabricated to investigate the impact of H2S on CO2 capture. Central to the setup will be a column housing the relevant adsorbent material. The column will then be exposed to atmospheric levels of CO2 and humidity, as well as H2S concentrations that are prevalent within a 200m radius of geothermal power plants and wells (0.2 to 5ppm). A CO2 sensor will monitor CO2 concentration at the breakthrough column’s outlet, while an H2S analyzer will regulate the inlet H2S concentration. Iterations of this will be done to compare the transient performance of the adsorbent. The project is slated to start around Q2 2025, with the relevant setup being assembled at the Dedan Kimathi University of Technology labs.
Budget
The budget items are essential for setting up and operating an experimental rig to study CO2 adsorption by DAC adsorbents in the presence of hydrogen sulphide (H2S). These include gas cylinders, valves, regulators, flowmeters, and sensors—all critical for conducting experiments that monitor CO2 capture under varying H2S concentrations, replicating conditions typical in geothermal-rich areas. The resulting data will form give an immediate idea of the impact of H2S on adsorbents, forming the basis for techno-economic assessments, with adsorbent performance as a key variable. This will provide a deeper, more granular understanding of the feasibility of scaling DAC technology with geothermal integration.
Project Timeline
This project will begin with a design phase for the breakthrough setup to aid in identifying the consumables needed. The consumables will then be purchased and shipped to Kenya for assembly. The breakthrough rig will then be built and commissioned in the Geothermal Training and Research Institute’s laboratory for experimental testing of the project. The data will be analyzed, and Techno-economic and Lifecycle models will be built to assess the efficiency and sustainability of the project.
Mar 05, 2025
Design the breakthrough setup
Mar 19, 2025
Purchasing and shipping of consumables to Kenya
Apr 18, 2025
Assembling the breakthrough test rig
May 16, 2025
Commissioning and preliminary testing of the rig
Sep 19, 2025
Undertaking the breakthrough experiments with test iterations around the varying H2S concentrations
Meet the Team
Affiliates
Team Bio
With 35 years of experience in applied geophysics, Prof. Mariita has significantly advanced Kenya’s geothermal exploration. His early role as a senior physicist and chief trainer at Kenya Electricity Generating Company was crucial in developing geothermal energy, now the largest source of installed power capacity in the country. To promote knowledge transfer, we will collaborate with GeTRI graduates specializing in geochemistry (MSc & BSc levels) for testing and data analysis.
Mike Bwondera
Mike Bwondera is the Research and Development Lead at Octavia Carbon, Global South’s first DAC company based in Nairobi, Kenya. With a background in mechanical engineering, Mike oversees a multidisciplinary team specializing in materials science, chemical and process engineering, instrumentation and controls. Under his leadership, the team has achieved several milestones, including open-sourcing the designs of Octavia’s first prototype, which forms the basis of the Open-Air Collective’s ‘Project Epiphyte’ work.
Additionally, he has established valuable partnerships with renowned researchers in the DAC space, enriching the company's technical capabilities and expanding its global network. A significant achievement during his tenure is securing a machine design patent, which has further solidified Octavia Carbon’s innovative position, and protected its intellectual property. Mike aims to fast-track the advancement of materials science and the scaling of innovative materials, understanding their critical importance in enhancing the efficiency of DAC technology.
In his previous work, Mike focused on clean water and sanitation projects, where he designed automated small-scale water treatment systems. His experience tackling engineering challenges has honed his ability to translate theoretical concepts into practical, impactful solutions.
Lab Notes
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Additional Information
Kenya, the eighth-largest producer of geothermal energy globally, has a 93% renewable energy grid, with ambitions to reach 100% by 2030. Geothermal energy currently accounts for 47% of the country’s total energy production—a figure that continues to rise. However, Kenya's vast geothermal potential remains largely underutilized due to a lack of industrial base load demand. Direct Air Capture (DAC) technology could serve as this much-needed demand, incentivizing the Kenyan government to fully transition the grid to 100% renewable energy. Given the energy-intensive nature of DAC technology, it stands to benefit immensely from this reliable, abundant, and low-cost energy source.
DAC plants integrated with geothermal resources are often positioned near geothermal wells, which produce steam laced with acid gases like hydrogen sulfide (H2S). Even though it is a toxic gas, this emitted H2S is usually at ultra low concentrations that poses no significant human health risk save for the pungent smell. Its acidic properties can however degrade adsorbent materials, reducing their performance and lifespan, even at low concentrations. This challenge is exacerbated by the large volumes of air DAC systems process, making it impractical to remove H2S using conventional scrubbing methods.
Therefore, without a clear understanding of how H2S affects DAC systems, scaling of DAC+ Geothermal integration may be difficult, highlighting the need for materials solutions that enhance adsorbent efficiency and longevity in H2S -rich environments. The outcomes of this project would not only inform performance projections but also contribute to material science advancements aimed at mitigating the effects of H2S and other unwanted gases on adsorbents. Ultimately, this research will unlock the potential for scaling DAC in geothermal-rich regions beyond Kenya, providing continuous, affordable green energy—a critical factor for the economic viability of DAC technology.
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