Twin carbon capture system: Direct air capture integrated with bio-gasification coupled amine-based carbon capture and storage system (Flexible Funding 2024)

Dr Mrinal Bhowmik, Dr Dibyendu Roy and Dr Shivaprasad Kumar Vijayalakshmi, from Durham University, were awarded funding in the UKCCSRC’s Flexible Funding 2024 call to look at “Twin carbon capture system: Direct air capture integrated with bio-gasification coupled amine-based carbon capture and storage system”.

Project Overview

The main project aim is to develop and evaluate an innovative and sustainable approach to a twin carbon capture system. This system combines a Biomass biomass-integrated gasification Combined Cycle (BIGCC), Direct Air Capture (DAC), and an amine-based CO₂ capture (AMINE) process to address carbon emissions comprehensively. By integrating DAC, flue gas treatment using AMINE and biomass energy generation, the project seeks to optimise carbon removal while producing clean energy, offering a unique pathway for effective decarbonisation (Figure 1).

Figure 1: Schematic representation of the twin carbon capture system integrating BIGCC, DAC, AMINE and storage processes

The research objectives focused on conceptualising the hybrid BIGCC-DAC-CCS system. The system captures CO₂ efficiently from atmospheric air and flue gases, highlighting its versatility. A detailed performance assessment explores the twin carbon capture system’s ability to achieve higher removal rates and energy efficiency, demonstrating its potential as a superior alternative to traditional approaches.

Economic and environmental feasibility are critical aspects of the project. This includes a comprehensive analysis of the levelised cost of CO2 capture (LCCC), energy requirements and CO₂ capture efficiency, ensuring the system delivers cost-effective solutions while reducing environmental impacts. The financial evaluation provides crucial insights into the technology’s long-term viability, emphasising its scalability and commercial applicability.

The project incorporates multi-objective optimisation to enhance system performance across key parameters such as efficiency, cost and carbon capture rate. Policy recommendations are developed to facilitate the adoption and commercialisation of DAC-based technologies, addressing market integration, regulations and scalability challenges. The project establishes the twin carbon capture system as a transformative solution for global decarbonisation initiatives by achieving these goals.

What We Did

This project involved the development of comprehensive thermodynamic models for the integrated twin-carbon capture system in the Aspen Plus platform, as illustrated in Figure 2. The models include BIGCC, DAC, AMINE and storage subsystems. Each subsystem was meticulously modelled to simulate the interlinked processes and evaluate their thermodynamic performance.

For the BIGCC subsystem, we modelled the gasification process, heat recovery and power generation pathways to ensure energy efficiency while capturing CO₂ from flue gas streams. We also developed detailed simulations of the DAC subsystem’s air contactor, pellet reactor and calciner to optimise CO₂ absorption and regeneration. The AMINE subsystem included precise modelling of the absorber, stripper and reboiler to quantify CO₂ recovery under various operating conditions.

We further incorporated a storage subsystem to model the compression, cooling and liquefaction of the captured CO₂ for subsequent storage or utilisation. The interconnected models were validated against existing literature and refined to ensure high accuracy. This modelling effort provided a robust framework to assess system performance, energy requirements and environmental impact under different operational scenarios.

Figure 2: Thermodynamic models of the twin carbon capture system, illustrating the individual subsystems: BIGCC, DAC, AMINE, and CO₂ storage

In addition to the technical aspects, this work required collaboration across disciplines to represent all physical and chemical processes accurately. This effort advanced our understanding of integrated carbon capture systems and laid the groundwork for further optimisation and potential policy recommendations for large-scale deployment.

Key Findings

CO₂ capture efficiency is assessed by comparing the CO₂ amounts at the inlet and outlet of the system. At the inlet, CO₂ is estimated at 150 tonnes per hour, while after processing, it is captured up to 120.3 tonnes per hour, indicating an 80% capture efficiency and optimised operating parameters. This highlights the system’s significant role in lowering CO₂ emissions, a key factor in industrial decarbonisation and climate mitigation.

Figure 3: Performance metrics and economic analysis of a CO2 capture system: (a) CO2 inlet and outlet flow rates illustrating an 80% capture efficiency, (b) effect of solvent temperature on CO2 capture percentage, (c) required power as a function of compression pressure, and (d) LCCC trend at different interest rates

The relationship between solvent temperature and CO₂ capture efficiency shows a decreasing trend, with capture efficiency starting at 84% at 30°C and dropping to around 77% as the solvent temperature rises to 100°C. This suggests higher temperatures impede absorption due to reduced solvent solubility or reactivity.

The power required for CO₂ compression varies non-linearly with pressure, initially decreasing as pressure increases and reaching a minimum at around 80–100 bar. Beyond this range, the power requirement rises again, indicating an optimal pressure range for minimising energy consumption and improving system efficiency.

The LCCC increases linearly with rising interest rates, reflecting the sensitivity of carbon capture costs to financial parameters. At 4%, it is around $240 per tonne of CO₂, rising sharply to $545 per tonne at 16%. This trend underscores the financial burden of higher borrowing costs. It highlights the importance of favourable terms and cost-reduction strategies to ensure long-term economic viability, particularly for large-scale energy projects.

What’s Next

This project has now reached completion. A poster summarising the findings was presented at the UKCCSRC Knowledge Exchange Conference 2024, where it won the Early Career Researcher (ECR) poster prize, along with a £250 professional development bursary. Also, a conference article was presented at an international conference in 2024 in India to disseminate key outcomes. One of the research papers from this project is planned for submission to a peer-reviewed journal in 2025. Research efforts will continue, focusing on further analyses and refinements of the developed model to enhance its applicability.

Our Poster Received the Early Career Researcher Poster Prize at the UKCCSRC Knowledge Exchange Conference 2024

Read more on Mrinal’s Flexible Funding 2024 project page.