Advancing Direct Air Capture: Digital Engineering for Carbon Removal Technology

The climate crisis is no longer a distant threat but a reality we face today. Since industrialization, humanity has released more CO₂ into the atmosphere than nature can absorb. Atmospheric CO₂ concentrations have risen from pre-industrial levels of 280 ppm to over 425 ppm today.In early 2022, atmospheric CO₂ concentrations averaged around 410 ppm, already approaching the critical 415 ppm threshold. Beyond this point, reversing the trajectory through human intervention alone would become extremely difficult.By 2024, this level had surpassed 420 ppm. It is now rapidly approaching 430 ppm, expected to exceed this level soon. We have already crossed the threshold. The situation has become so severe that reducing atmospheric carbon is no longer feasible; our remaining task is to slow the rate of increase. To prevent the most catastrophic effects of climate change, experts agree that it is not enough to reduce emissions. , but Humanity must remove approximately 190 gigatons of CO₂ already accumulated in the atmosphere. Net-zero is not enough. We must achieve net negative.

Direct Air Capture: Technology to Remove Atmospheric Carbon

Direct Air Capture (DAC) is a technology that extracts CO₂ directly from ambient air for permanent storage or utilization. Unlike conventional CCS (Carbon Capture and Storage) that addresses emissions from industrial sources, DAC can be deployed anywhere, capturing CO₂ already dispersed in the atmosphere.DAC technologies are typically categorized into two main type:① Liquid Solvent-based SystemsUtilize alkaline solutions like potassium hydroxide (KOH) or sodium hydroxide (NaOH) to absorb CO₂, then regenerate at high temperatures (above 900°C).These methods are well-proven but energy intensive.② Solid Sorbent-based Systems Use solid materials to adsorb CO₂ , then regenerate at relatively lower temperatures (80-120°C) under vacuum. These systems offer higher energy efficiency and easier modularization, though challenges remain in sorbent performance and durability.

The Barrier to Commercialization: Energy and Cost

The biggest challenge for DAC deployment is economics. With atmospheric CO₂ concentrations around 420 ppm—hundreds of times more dilute than in industrial exhaust streams (10–25%)—massive air volumes must be processed, consuming significant energy for both capture and regeneration.Current DAC facilities remove approximately 0.01 megatons of CO₂ per year. To achieve a lmeaningful climate impact, this must scale rapidly to 85 megatons annually by 2030 and more than 10 times again by 2050. Lowering energy intensity and operational cost is the central challenge for large-scale DAC deployment.

Company G (USA): Moonshot for Low-Cost DAC Technology

Global technology leader Company G (USA) launched a Moonshot Project in 2018 to develop a more economical and energy-efficient DAC solution. The core idea was clear: Design a system that operates at low temperatures, powered primarily by waste heat from industrial facilities such as data centers.

Innovative Sorbent That Works Like a Sponge

The team engineered a novel sorbent composed of amorphous silica pellets—an inexpensive, non-toxic drying agent coated with CO₂-binding chemicals. Acting like a sponge, the sorbent soaks up atmospheric CO₂ and can be “wrung out” for reuse..After testing 70 different approaches and 700 chemical formulations, the team optimized the sorbent’s performance. In the final configuration, large fans draw air into the system where CO₂ adheres to the sorbent. The sorbent circulates through the chamber similar to snowflakes in a snow globe, and carbon-saturated sorbent moves to a separate desorption chamber.

Industrial Waste Heat Utilization:A Breakthrough in Energy Efficiency

In the desorption chamber, vacuum and moderate heat are applied to release the captured CO2. Remarkably over 80 percent of the required heat is supplied from industrial waste sources, it is the core innovation that reduces operational costs to roughly one-third of conventional DAC systems., clean air is released back to the atmosphere, while captured CO₂ is compressed for storage. The regenerated sorbent is recycled back into the system. Interestingly, this process generates approximately two tons of clean water per ton of CO₂ captured, water can be repurposed for cooling in data centers or other industrial uses.

SIMACRO's Role: Digital Modeling for Process Integration and Optimization

SIMACRO participated in this initiative as a modeling specialist, contributing to process integration and energy efficiency optimization studies. Using Aspen Plus, SIMACRO developed an integrated modeling framework coupling vacuum desorption with low-grade waste heat recovery systems.The modeling work focused on three critical areas:① Vacuum Desorption System DesignOperating under vacuum conditions enables effective separation of H₂O and CO₂ even at reduced temperatures. This minimizes energy use and protects sorbent materials from thermal oxidation, extending their service life.② Waste Heat Recovery and Integration ArchitectureSIMACRO designed a multi-stage heat recovery system using a heat pump (using HFO-1234ZE refrigerant) to upgrade low-grade waste heat and redistribute it efficiently across evaporation, desorption, and cooldown stages. This minimizes the high-grade energy that must be supplied externally.③ Complete Process Simulation and Control StrategyThe model analyzed the entire process from air intake through CO₂ storage. By incorporating material balances for sorbent circulation, moisture uptake, and CO₂ loading, the simulation provided control strategies for stable, continuous operation. Just as AI-powered software optimizes the system by adjusting airflows, sorbent speeds, and temperatures, SIMACRO's model enabled validation of how the process responds under diverse operating conditions before physical construction.

Key Optimization Pathways Identified Through Simulation

Through integrated process simulation, SIMACRO identified specific pathways to reduce energy intensity in DAC operations:① Strategic Utilization of Low-Grade Waste Heat Confirmed that industrial waste heat, typically rejected, could be effectively utilized for sorbent preheating and water evaporation, significantly reducing primary energy demand.② Heat Upgrading Through Heat Pump Integration Demonstrated how low-grade heat could be upgraded to required temperatures and redistributed throughout the process, improving overall thermal efficiency.③ Advantages of Vacuum Operation Verified that vacuum operation reduces both temperature and energy requirements compared to atmospheric pressure while simultaneously protecting sorbent materials from oxidative degradation, extending their lifetime.

Contributing to DAC Commercialization

This collaboration provided technical validation for integrating vacuum desorption with industrial waste heat recovery in DAC systems , directly supporting Company G’s pilot-scale design decisions. The project demonstrates how digital engineering supports the development of breakthrough climate technologies. By enabling detailed analysis of energy flows and process integration opportunities before physical construction, it helps reduce both technical risk and development costs associated with novel carbon removal approaches.

Conclusion: Digital Engineering Making DAC Real

The journey from laboratory concept to industrial-scale facility capable of removing atmospheric carbon faces significant challenges. Dilute CO₂ concentrations, massive air volumes, high energy demands. These obstacles cannot be overcome without systematic process optimization.Digital twin and advanced process modeling are essential tools for bridging this gap. They analyze complex energy flows, identify waste heat recovery opportunities, and validate process stability across diverse operating scenarios. Evaluating and optimizing hundreds of design options before constructing physical facilities is how digital engineering contributes to DAC commercialization.Current DAC plants worldwide remove approximately 0.01 megatons of CO₂ per year. Scaling to 85 megatons by 2030 and more than 10 times that by 2050 requires both technological innovation and systematic process engineering.SIMACRO's core competency lies in advanced modeling and simulation, integrated with data management, contextualization, data analysis, and AI Agent technologies that enable intelligent process optimization. As carbon removal technologies like DAC advance from pilot demonstrations toward gigaton-scale deployment, these digital engineering capabilities will play an increasingly vital role.Looking more broadly, addressing the climate crisis extends beyond DAC alone. CO₂ capture, clean hydrogen production, circular economy development. All climate technologies require the convergence of process engineering and digital intelligent operation to move from research stages to commercially viable solutions.Leveraging proven expertise in global collaborations and digital engineering, SIMACRO aims to lead the digital transformation of process industries. Under its vision of 'realizing a sustainable future through digital twin technology', SIMACRO continues to pioneer innovation that turns sustainability into engineered reality.With headquarters in Boston and Seoul, SIMACRO has completed over 90 commercial modeling projects across 40 companies since 2018. Collaborating with global technology leaders such as AspenTech, Emerson, and OLI, SIMACRO is committed to advancing digital innovation in the process industry.About SIMACRO​Designer