Scopus Publications
- Hydraulic Impacts of Salt Precipitation in CO2 Storage: Roles of Wettability, Permeability, and Injection Rate
Amina Togay, Reza Khoramian, Woojin Lee
Energy and Fuels, 2026
Salt precipitation during CO2 injection can alter injectivity and storage behavior, but its impact remains unclear because it is often evaluated based on salt presence rather than hydraulic consequences. This study examines when halite becomes flow-restrictive and how permeability, wettability, and injection rate jointly control salt-driven changes in trapping and plume migration. Fully compositional CMG–GEM simulations were performed across multiple permeability classes and wettability states (water-wet and weakly water-wet) under varying injection regimes. Permeability classes were defined based on formation transmissibility ranges, with low-permeability (0.8–2.6 mD), midpermeability (4–13 mD), and high-permeability (8–26 mD) systems representing tight to moderately conductive saline aquifers. Paired runs with and without water vaporization isolated the role of salt formation, and a plume-scale segregation index was introduced to link trapping partitioning with vertical migration. The results show that salt impact is governed by hydraulic restrictiveness. In low-permeability formations under high flow rates, restrictive salt banking increases capillary trapping by ∼18–23% and reduces plume segregation by up to ∼50%. Midpermeability systems exhibit partially restrictive behavior, where salt primarily redirects flow, enhancing dissolution by ∼3–4% while leaving residual trapping nearly unchanged (±1%). In high-permeability reservoirs, salt is largely nonrestrictive, producing subpercent trapping changes and minimal migration sensitivity. Wettability exerts a conditional influence, becoming important only when permeability and injection rate allow sustained dry-out with a continued brine supply, resolving previously inconsistent wettability trends. Overall, the study answers key questions on salt severity by showing that halite acts as a regime-dependent control on CO2 storage. The results provide a practical framework for identifying when salt precipitation alters trapping and migration, supporting more reliable screening and design of geological CO2 storage systems. - Development of a chemically optimized CO2 foam in saline reservoirs: pore-scale visualization, and CFD modeling
Reza Khoramian, Nariman Algazinov, Amina Togay, Woojin Lee
Journal of Industrial and Engineering Chemistry, 2026 - Optimizing carbon capture and storage (CCS) infrastructure development using a python tool for source-sink matching and cluster formation
Amina Togay, Gaini Serik, Woojin Lee
Journal of Cleaner Production, 2025
The large-scale deployment of Carbon Capture and Storage (CCS) infrastructure is critical for Kazakhstan's decarbonization strategy, particularly in hard-to-abate industries. This study develops an optimization-driven framework for CCS infrastructure planning, focusing on source-sink matching and cost-effective clustering of emitters. A Python-based mixed-integer linear programming (MILP) model is applied to identify optimal CCS hub configurations by minimizing the total cost of capture, transportation, and storage while accounting for environmental impact. The results demonstrate that a 100 km clustering radius achieves the lowest cost scenario, with full redirection costing approximately $23.30 billion and partial redirection $24.02 billion. However, the CO 2 net abated is highest in this scenario, with emissions reaching 140.55 MtCO 2 and 142.73 MtCO 2 , respectively. A 240–300 km clustering radius offers a more balanced trade-off, stabilizing costs at approximately $34.57 billion while reducing emissions. The analysis also reveals that capture costs represent the greatest portion of total CCS expenses (50.47 % at 100 km), while transportation costs increase with clustering radius, rising from 45.61 % to 61.01 % at 180 km. Leveraging existing pipeline infrastructure significantly improves cost efficiency, particularly in shorter clustering radii. The findings highlight the importance of integrating cost-efficient CCS hub networks and policy interventions, including regulatory frameworks, financial incentives, and international cooperation, to accelerate Kazakhstan's transition to a low-carbon economy. Future research should refine dynamic clustering models and incorporate real-time storage capacity assessments for improved decision-making. To enhance model repeatability, we provide an open-source Python code for future use. • First optimized CCS hubs in Central Asia using MILP modeling. • Developed a new method with full and partial redirection for source-sink matching. • Identified 17 storage sites with 5784 Mt CO 2 capacity. • Found 100 km clustering minimizes cost, while 240–300 km balances emissions. • Created an open-source Python tool for flexible CCS planning. - Development of carbon capture and storage (CCS) hubs in Kazakhstan
Nurgabyl Khoyashov, Gaini Serik, Amina Togay, Yerdaulet Abuov, Alisher Alibekov, Woojin Lee
International Journal of Greenhouse Gas Control, 2024
• Kazakhstan's CO 2 emissions come from electricity sectors concentrated in the North. • Eight CCUS hubs in Kazakhstan aim to capture 115 Mt of CO 2 annually by 2060. • Ammonia and natural gas plants are prime candidates for CCUS. • Atyrau hub shows high CO 2 capture rates at relatively low costs. • Kazakhstan's CCUS hub infrastructure needs US$84.2 billion. The competitiveness of both the power and industry sectors in Kazakhstan is due to the use of cheap fossil fuels. Due to the projected large-scale deployment of renewable energy sources in the future, some portions of cheap coal and hydrocarbon use are planned to be phased out in Kazakhstan. In its net-zero journey, the country still intends to have GHG emissions from reduced use of fossil fuels and “hard-to-electrify” industries such as chemicals, cement, and iron/steel sectors. Carbon capture and storage (CCS) is a decarbonization solution to existing fossil fuel-fired power plants and other hard-to-abate industries in the net-zero age, which Kazakhstan officially plans to reach by 2060. This study covers three major research tasks on large-scale CCS deployment in Kazakhstan. The study first reveals the “low-hanging fruits” of CO 2 capture in the natural gas processing and ammonia production industries, with a low cost of capture of $29 per ton of CO 2 captured each, by comparing the costs of capture in Kazakhstan with those of power plants, steel factories, cement plants, refineries, and hydrogen plants. Secondly, this work shows that developing CCS projects in hubs of multiple emitters can bring cost-efficient deployment of CCS in Kazakhstan. Lastly, we presented our vision of how CCS could be a part of Kazakhstan's big net-zero plan in 2060. Our estimates show that 8 CCS hubs in Kazakhstan with a total capacity of 115 Mt CO 2 /year could cost $87 billion in capital expenditures (CAPEX) until 2060. While CO 2 capture remains the most expensive component of CCS process chains globally, compressing and transporting CO 2 poses significant cost challenges in Kazakhstan due to the long distances between emission sources and storage sites. Future research endeavors could explore automated tools to optimize logistical considerations and enhance the accuracy of cost estimations. Moreover, further studies should incorporate site-specific data to reduce assumptions and refine CCS potential assessments in Kazakhstan. - Resource assessment for green hydrogen production in Kazakhstan
Akmaral Tleubergenova, Yerdaulet Abuov, Saniya Danenova, Nurgabyl Khoyashov, Amina Togay, Woojin Lee
International Journal of Hydrogen Energy, 2023
Kazakhstan has long been regarded as a major exporter of fossil fuel energy. As the global energy sector is undergoing an unprecedented transition to low-carbon solutions, new emerging energy technologies, such as hydrogen production, require more different resource bases than present energy technologies. Kazakhstan needs to consider whether it has enough resources to stay competitive in energy markets undergoing an energy transition. Green hydrogen can be made from water electrolysis powered by low-carbon electricity sources such as wind turbines and solar panels. We provided the first resource assessment for green hydrogen production in Kazakhstan by focusing on three essential resources: water, renewable electricity, and critical raw materials. Our estimations showed that with the current plan of Kazakhstan to keep its water budget constant in the future, producing 2–10 Mt green hydrogen would require reducing the water use of industry in Kazakhstan by 0.6–3% or 0.036–0.18 km3/year. This could be implemented by increasing the share of renewables in electricity generation and phasing out some of the water- and carbon-intensive industries. Renewable electricity potential in South and West Kazakhstan is sufficient to run electrolyzers up to 5700 and 1600 h/year for wind turbines and solar panels, respectively. In our base case scenario, 5 Mt green hydrogen production would require 50 GW solar and 67 GW wind capacity, considering Kazakhstan's wind and solar capacity factors. This could convert into 28,652 tons of nickel, 15,832 tons of titanium, and many other critical raw materials. Although our estimations for critical raw materials were based on limited geological data, Kazakhstan has access to the most critical raw materials to support original equipment manufacturers of low-carbon technologies in Kazakhstan and other countries. As new geologic exploration kicks off in Kazakhstan, it is expected that more deposits of critical raw materials will be discovered to respond to their potential future needs for green hydrogen production.
