Flexible Funding 2023: Dr Laura Herraiz, Heriot-Watt University

Exploring the use of Rotary Adsorption Systems for Direct Air Carbon Capture and Storage (DACCS) applications

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Key facts about this Flexible Funding research project

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Institution: Heriot-Watt University
Department: School of Engineering and Physical Science
Start date: 1 October 2023
Principal investigator: Dr Laura Herraiz
Co-Investigators: -
Amount awarded by UKCCSRC: £29,991

Why is this research needed?

Engineering Greenhouse Gas Removal (GGR) from both bio-energy with CCS (BECCS) and direct air carbon capture and storage (DACCS) is heavily relied on in most IPCC mitigation pathways to counterbalance hard-to-abate residual emissions, if net-zero greenhouse gas (GHG) emissions are to be achieved (IPCC, 2022). DACCS has progressed significantly in the last years to merit inclusion in several countries’ mitigation plans. The UK’s Industrial Decarbonization Strategy estimates that approximately75-81 MtCO2-eq per annum of GGR will be required to achieve the UK’s economy-wide net zero greenhouse gas emissions targets by 2050 (HM Gov, 2021). A portfolio of GGR methods, including DACCS, needs to be demonstrated to operate at large scales to deliver on this target. DACCS technology faces several challenges, including large energy requirements and significant capital costs. Early capture cost estimates for DACCS are wide-ranging and uncertain and exceed 600 USD/t CO2, reflecting the early stage of technology development, though more recent estimates suggests that a price below 200 USD/t CO2 may be possible (Keith et al., 2018).

The aim of this project is to investigate cost-effective DACCS technologies by exploring process intensification strategies and optimum material-process synergies. This will lead to a reduction in size and energy requirements of the process, lowering the associated capital and operational costs. This project focuses on the use of regenerative rotary adsorbers with structured adsorbents in the wheel rotor. Rotary systems constitute a relatively simple and compact configuration to perform rapid temperature swing adsorption cycles and the geometry of structured adsorbents can be tailored to maximise contact surface area and minimise pressure drop. An open-source module that includes the model of the rotary adsorber will be developed and implemented for high-throughput screening of adsorbent materials. A value-chain analysis that includes process, techno-economic and environmental considerations will inform the screening study that will identify the best candidates for DACCS.

For the execution of the project, Heriot Watt University will partner with Howden Group, an original equipment manufacturer (Glasgow, Scotland) leader on rotary heat exchanger and custom engineered centrifugal fans primarily for the power generation and steel industries. Howden presents over 10 years involvement in fundamental CCUS research and has provided collaborative support for associated universities in the development of carbon capture technologies and provided equipment for worldwide CCUS demonstration projects. This project will benefit from Howden’s industrial perspective and review of the techno-economic evaluation of the technology as well as attendance at industrial workshops and advisory panel meetings in Edinburgh. Howden will provide in-kind contribution to a maximum £10k per annum.

What is this research investigating?

The aim of this project is to investigate cost-effective DACCS technologies by exploring process intensification strategies and optimum material-process synergies.

The specific measurable objectives are:

1) the development of an open-access Regenerative Rotary Wheel model;

2) identification of top-performing adsorbent materials when a rotary process is used;

3) perform an analysis of the technical and economic feasibility of rotary systems for DAC applications and the requirements for its cost-effective integration within the UK Industrial Clusters.

Rotary adsorption for carbon capture and storage (CCS) applications has been investigated at pilot plant scale as part of the “Adsorption Materials and Processes for Gas-fired power plants” (AMPGas) project. Svante (formerly Inventys) proposed the VeloxoTherm process for carbon capture based on this technology and has a strong patent portfolio on Rapid Cycle Temperature Swing Adsorption (RC-TSA) processes using structured adsorbents, and steam-assisted direct regeneration with fast kinetics as an alternative to traditional liquid amine technologies. Svante has been pioneering the field-testing of the VeloxoThermTM Rapid Cycle Temperature Swing Adsorption process to capture 1 tpd CO2 from cement flue gas. They use a scaled-up novel sorbent material, i.e. Svante’s Zinc-based Calgary Framework 20 (CALF-20), which was found to be best sorbent candidate for this application.

The characteristics of rotary systems make them especially attractive for DACCS applications, where the CO2 concentration in the air is extremely low (0.04%vol). Rotary systems constitute a relatively simple and compact configuration to perform rapid TSA cycles with a potential to substantially decrease equipment size and energy consumption per tonne of CO2 captured, and a subsequent investment and operational cost reduction. For DAC applications, fast kinetics, low mass transfer resistance and very low-pressure drops are desirable to ensure a process performance that can lead to reduced capital and operational costs.

Additionally, the sorbent material is at the heart of the process and synergies must be explored between materials and processes to find the optimal combination for a particular application. This motivates this proposal, where the innovative aspect is the development and implementation of a TSA rotary adsorption system module in an open-source software (e.g. Python) for a rapid screening of adsorbent materials for DAC applications. This will allow identification, from databases of nanoporous materials, the best candidates for DAC processes. A high-throughput screening study will target DAC systems that can be integrated into the current UK CCUS Industrial Clusters to benefit from existing infrastructure and the large storage potential that the UK offers. A value-chain analysis including the evaluation of process, economic and environmental key performance indications will inform the screening studies. This will allow us to evaluate the technical and economic feasibility of rotary systems for DAC applications and the requirements for its cost-effective integration within an industrial cluster.

What does the research hope to achieve?

Advice from industrial experts such as Howden Group, is key in this type of projects where the focus is on feasibility studies. It will help us to improve the accuracy and relevance of the contactor’s mechanical design and the economic evaluation. We believe it will constitute a step change on the future development of advanced contactors towards achieving very low pressure drops and large contact surface areas, particularly important for DACCS applications. Additionally, an exchange of fundamental principles of adsorption and practical applications constitutes an important driver for innovation and qualified workforce.

Beyond this interaction, this project aims to inform the research community in the UK and globally, providing insights on material characteristics, process parameters, technical, economic and environmental aspects of DACCS technologies and its integration within industrial CCUS clusters.

Key findings and research outcomes will also inform adsorbent material developers and technology developers on key requirements needed to reduce costs in DACCS. They will also inform other stakeholders interested on the deployment of DACCS as part of their portfolio of projects in the UK CCUS Industrial clusters, and to accelerate global emissions reductions. All of them will benefit from the evidence-based knowledge and recommendations on what would be the most cost-efficient capture technology for DACCS in specific industries and considering the local constraints.

This project provides opportunities for capitalising on our on-going research projects at the Research Centre for Carbon Solutions (RCCS) at Heriot Watt University, which cover the whole CCUS chain. The contactor model and technoeconomic model developed in this proposal will be integrated into our value-chain PrISMa platform, an open-source modelling tool developed within the scope of the ACT-funded PrISMa project and the follow-on USorb-DAC project. Results from this project will also be available to the public via the platform. We will also make use of our established research networks to maximize the return on investment and to facilitate knowledge exchange and exploitation and dissemination of results to much wider audiences and public awareness.

Research outputs

This research is ongoing. Outputs will be shared below as they become available.