Novel concept for efficient and clean power production from natural gas

Significance 

At present, slightly over 80% of the total energy demand is satisfied by fossil fuels. With more stringent policies and increasing global awareness of the effects of excessive CO2 emissions, this is subject to decrease. Steps to reduce CO2 emissions involve increasing energy efficiency, switching to less carbon-intensive fuels like natural gas, adopting green energy systems like renewables and nuclear, and the deployment of CO2 capture and sequestration (CCS) technologies.

CO2 capture methods are broadly classified into three types: pre-, post-, and oxy-combustion. A more efficient application of oxy-combustion is currently being investigated: gas switching technology. It is based on the principle of chemical looping, which is gaining momentum particularly due to its ability to inherently separate CO2 with no direct energy penalty. To this end, two types of chemical looping systems have been reported, namely: chemical looping combustion (CLC) and chemical looping reforming (CLR). Gas switching technologies differ from chemical looping in that, instead of circulating an oxygen carrier material between two reactors, the oxygen carrier kept in a single reactor and the gas feed to the reactor is switched. This allows easier scale-up and pressurization of these reactors, the latter being a requirement for high process efficiencies. When CLR is applied using the gas switching principle, it can be configured for efficient pure hydrogen production, which can be exported or combusted in a power plant called the gas switching reforming combined cycle (GSR-CC) plant.

In this context, Norwegian University of Science and Technology scientists: Dr. Shareq Mohd Nazir, Dr. Shahriar Amini and Dr. Jan Hendrik Cloete, in collaboration with Dr. Schalk Cloete atSINTEF Industry, presented a study where they optimized the GSR-CC plant. The study focused on evaluating the different process integration options that could reduce the efficiency penalty and simplify the GSR-CC process layout to make it more suitable for flexible power or hydrogen production. Their work was recently published in the research journal, Energy.

In brief, the research approach presented five cases, in which a systematic approach was adopted to improve the net electrical efficiency of the GSR-CC process. Two cases focused on reducing the number of unit operations and the other three cases focused on heat integration. In addition, an improved gas turbine configuration was proposed for the direct injection of the hot N2-rich stream from the GSR reactors into the combustion chamber, where it could aid in controlling the lean pre-mixed combustion – a known problem area in hydrogen turbines.

In summary, the study by Dr. Shareq Mohd Nazir and his colleagues successfully presented a means to improve the GSR-CC process, which comprises of a novel gas switching reforming (GSR) process for hydrogen production with integrated CO2 capture linked to a combined cycle to generate electricity from the produced hydrogen gas. The net electrical efficiency of the GSR-CC process could be improved, while simultaneously improving plant flexibility and offering a potential solution to premixed combustion of hydrogen. This flexible GSR-CC plant offers a promising solution for the ongoing global energy transition because it can integrate higher shares of fluctuating wind and solar power and supply clean hydrogen for decarbonizing transport and industry.

This work is part of “GaSTech” project under the Horizon 2020 programme, ACT Grant Agreement No 691712. GaSTech aims at demonstrating gas switching technology for accelerated scale-up of pressurized chemical looping applications.

About the author

Shareq Mohd Nazir is a researcher in area of clean energy conversion processes with special focus on hydrogen production and carbon capture and sequestration. He mainly works with process synthesis, design, modeling and simulation and techno-economic assessment. He obtained his Phd in Energy and Process Engineering at the Norwegian University of Science and Technology. Having obtained his B.E. (Hons) and ME degree in Chemical Engineering from Birla Institute of Technology and Science Pilani, he has experience in working for metals and chocolate industry.

About the author

Dr. Jan Hendrik Cloete is currently working as a researcher at SINTEF Industry in Trondheim, Norway. He completed his M.Eng in Extractive Metallurgy at the University of Stellenbosch, South Africa in 2014 and his PhD at the Norwegian University of Science and Technology in 2018. The topic of his PhD was the development of multiscale models for industrial-scale fluidized bed reactor simulations.

His current research focusses on the modelling of multiphase reactors using computational fluid dynamics (CFD), with a particular interest in reactors for carbon capture and the use of multiscale methods to enable accurate industrial-scale simulations.

About the author

Schalk Cloete holds B.Sc. and M.Sc. degrees in Chemical Engineering from Stellenbosch University and a PhD in Computational Fluid Dynamics from the Norwegian University of Science and Technology. He has published 65 papers in leading journals with an h-index of 18. Schalk’s current research is focussed on designing novel clean energy conversion processes and integrating these processes into the energy system of the future.

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About the author

Shahriar Amini completed a PhD in Chemical Engineering from The University of New South Wales (UNSW) and Australian Commonwealth Scientific and Research Organization (CSIRO), Australia.

He has been leading large international R&D projects at SINTEF Industry and Norwegian University of Science and Technology (NTNU), Norway since 2008. Prior working at SINTEF, he held Post Doctoral positions at Delft University of Technology, Netherlands and University of Manchester, UK.

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Reference

Shareq Mohd Nazir, Jan Hendrik Cloete, Schalk Cloete, Shahriar Amini. Gas switching reforming (GSR) for power generation with CO2 capture: Process efficiency improvement studies. Energy, volume 167 (2019) page 757-765.

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