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The Clean Fossil and Bioenergy (CleanFaB) Research Group

The Clean Fossil and Bioenergy (CleanFaB) Research Group is an interdisciplinary team of researchers. The main area of research is on how clean energy technology and greenhouse gas removal (GGR) will enable a cost-effective transition to a low-carbon energy system. Some key technologies the group considers include fossil fuels used in conjunction with CCS and negative emission technologies (i.e., GGR) such as bioenergy with CCS (BECCS) and direct air capture of CO2 (DAC). From engineering to economics, we are determined to make this adaptation as successful as possible.

 

Future Cooperation with TCM
We see the potential for further investigation of flexible operation strategies, particularly if the process control system at TCM is optimised for dynamic operation (e.g., to achieve higher ramp rates). Whilst the motivation of this first test was to validate our predictions from our models, future work will aim to determine the dynamic plant set-point conditions that will deliver an overall CO2 capture rate of 90%.

Dr Mai Bui and Dr Niall Mac Dowell have worked together to develop this TCM study on flexible operation. Dr Mai Bui is a Research Associate in the Centre for Environmental Policy at Imperial College London. She has first-hand experience in designing pilot plant test campaigns and dynamic operation of pilot plants, including CSIRO’s pilot plant (AGL Loy Yang power station, Australia) and the CO2 capture facility at TCM (Mongstad, Norway). Also, she has developed dynamic models of small-scale (UKCCSRC PACT pilot plant, CSIRO’s pilot plant at Loy Yang) and large-scale systems (TCM CO2 capture facility, Norway). Dr Niall Mac Dowell is a Reader in the Centre for Environmental Policy at Imperial College London, where he currently leads the Clean Fossil and Bioenergy Research Group. He leads a research group consisting of 3 PDRAs, 14 PhD students, all of whom study the development of clean energy and greenhouse gas removal technologies at multi-scale, from molecular to process to network scale. Both have published a number publications in the field of CCS, specifically on techno-economic optimisation, flexible operation and efficiency enhancements.

Brief description of your workplace

The Clean Fossil and Bioenergy (CleanFaB) Research Group is an interdisciplinary team of researchers. The main area of research is on how clean energy technology and greenhouse gas removal (GGR) will enable a cost-effective transition to a low-carbon energy system. Some key technologies the group considers include fossil fuels used in conjunction with CCS and negative emission technologies (i.e., GGR) such as bioenergy with CCS (BECCS) and direct air capture of CO2 (DAC). From engineering to economics, we are determined to make this adaptation as successful as possible.

Why did you participate in this test?

Our main motivation was to test the performance of two novel approaches to flexible operation (developed from previous process modelling work): (i) time-varying solvent regeneration, and (ii) variable ramp rate. Although they appear promising based on our modelling results, we needed to demonstrate that these strategies are practical from a plant operability perspective. Additionally, we have conducted flexible operation studies at small scale CO2 capture pilot plants (~1 tCO2/day). To understand the impact of plant scale on the dynamics of a CO2 capture plant, we need to combine dynamic plant data from plants of different sizes. Thus, participating in a test at the TCM facility was an ideal opportunity to acquire data from a large scale plant. We are combining the insights from dynamic studies at different CO2 capture plants to further develop our knowledge on this research question.

Briefly describe your project on TCM

This study investigates the feasibility of flexible operation in post-combustion CO2 capture plants by demonstrating some novel approaches to dynamic operation. Firstly, the effect of stream flow rate on the performance of the process is established. The time-varying solvent regeneration strategy demonstrates the ability to store CO2 within the working solvent, which would avoid the need for solvent storage tanks. Secondly, the variable ramp rate scenario investigates the ability to ramp process parameters at different rates (at constant liquid to gas ratio, L/G). Whilst the achievable ramp rate of power plants is well understood, the ramping limitations of CO2 capture plants require further investigation.

What has your contribution been?

We designed a pilot plant test schedule to simulate two novel flexible operation strategies, time-varying solvent regeneration and variable ramp rate. With our expertise in dynamic operation of amine-based CO2 capture plants, we could work in collaboration with TCM staff to design a test schedule that was suitable for implementation at the TCM CO2 capture plant. We have developed a validated dynamic model of the TCM CO2 capture that has been used to simulate our flexible operating strategies.

Which results are you most proud of?

The experimental study of three flexible operation scenarios (effect of steam flow rate, time-varying solvent regeneration and variable ramp rate) has provided invaluable insight into the dynamics of a CO2 capture plant. We understand the direct relationship between steam flow rate decreases, CO2 capture rate and lean solvent CO2 loading. The time-varying solvent regeneration scenario was successfully demonstrated at the TCM CO2 capture plant. The test results reveal that CO2 could be stored within the working fluid, where lean solvent loading increased from 0.16 mol CO2/mol MEA (CO2 capture rate 89–97%) up to 0.48 mol CO2/mol MEA (capture rate 14.5%). The variable ramp rate scenario demonstrated that different ramp rates can be applied successively to a CO2 capture plant. By maintaining constant L/G ratio during the changes, the CO2 capture performance remained the same – constant lean CO2 loading of between and CO2 capture rate.

TCM’s importance to your results?

TCM has had a major role in the development of a suitable operating procedure/schedule for our flexible operation test campaign. They have been exceptional in terms of providing data and information about the TCM CO2 capture plant in a prompt and timely manner. The plant data from TCM has been invaluable to developing an understanding of the process dynamics of an absorption-based CO2 capture process. These insights will be essential in our other work on flexible operation of CO2 capture processes.

What would you emphasise as TCM’s three main benefits as a test arena?

  • The absorbent-based CO2 capture plant is one of the largest test facilities in terms of scale.
  • An experienced team of operators and engineers work onsite – they help ensure that the operating regime designed is feasible and conducted efficiently.
  • The quality of the plant data is very high. Plant results have good reproducibility and key process measurements are available for almost every stream. The plant is equipped for dynamic process measurements of solvent CO2

Where are the results shared

This work will be presented at the GHGT-14 conference in Melbourne, Australia. The results will be published in two papers in the International Journal of Greenhouse Gas Control (IJGGC):

Bui, M., Mac Dowell, N., (2018). Flexible operation of CO2 capture processes at different plant scales. International Journal of Greenhouse Gas Control, draft.

Bui, M., Flø, N. E., de Cazenove, T., Mac Dowell, N., (2018). Demonstrating flexible operation of CO2 capture plants at Technology Centre Mongstad (TCM). International Journal of Greenhouse Gas Control, draft.