• Energy Research

High-temperature solid looping technologies, such as calcium looping and chemical looping combustion are regarded as emerging CO2 capture technologies with potential to reduce the net efficiency penalties associated with CO2 separation. Importantly, high-temperature operation of these technologies allows utilisation of the high-grade heat for power generation. Building on these emerging technologies, this study intended to establish a new class of high-temperature solid looping combustion technologies for high-efficiency low-emission power generation called calcium looping combustion. Such combustion technology comprises a combustor, as a primary source of heat for indirect heating in a calciner, and a carbonator where CO2 is separated from flue gas leaving the combustor; hence high-grade heat, which can be used for power generation, and a concentrated CO2 stream, which can be either utilised or permanently stored, are generated. The techno-economic performance of calcium looping combustion was comparable to a conventional coal-fired power plant. Depending on whether the concentrated CO2 stream is utilised elsewhere or permanently stored, calcium looping combustion was characterised with a net efficiency gain of 0.7%HHV points or a net efficiency penalty of 2.4%HHV, respectively. Additionally, the cost of CO2 avoided for calcium looping combustion was estimated to be 10.0 €/tCO2 and 33.9 €/tCO2, respectively. Therefore, similarly to chemical looping combustion, calcium looping combustion introduced in this study is a viable high-efficiency low-emission power generation technology that produces a concentrated CO2 stream with no efficiency penalty associated with CO2 separation.

High-temperature solid looping technologies, such as calcium looping and chemical looping combustion are regarded as emerging CO2 capture technologies with potential to reduce the net efficiency penalties associated with CO2 separation. Importantly, high-temperature operation of these technologies allows utilisation of the high-grade heat for power generation. Building on these emerging technologies, this study intended to establish a new class of high-temperature solid looping combustion technologies for high-efficiency low-emission power generation called calcium looping combustion. Such combustion technology comprises a combustor, as a primary source of heat for indirect heating in a calciner, and a carbonator where CO2 is separated from flue gas leaving the combustor; hence high-grade heat, which can be used for power generation, and a concentrated CO2 stream, which can be either utilised or permanently stored, are generated. The techno-economic performance of calcium looping combustion was comparable to a conventional coal-fired power plant. Depending on whether the concentrated CO2 stream is utilised elsewhere or permanently stored, calcium looping combustion was characterised with a net efficiency gain of 0.7%HHV points or a net efficiency penalty of 2.4%HHV, respectively. Additionally, the cost of CO2 avoided for calcium looping combustion was estimated to be 10.0 €/tCO2 and 33.9 €/tCO2, respectively. Therefore, similarly to chemical looping combustion, calcium looping combustion introduced in this study is a viable high-efficiency low-emission power generation technology that produces a concentrated CO2 stream with no efficiency penalty associated with CO2 separation.

The concentration of CO2 in the atmosphere has recently exceeded 420 ppm and continues to rise, mainly because of the combustion of fossil fuels, contributing significantly to climate change. CO2 capture, utilization and storage has become recognized as a critical approach to reducing energy and industrial emissions. CO2 utilization through the electrochemical reduction route is a novel alternative to CO2 storage. Microfluidic electrolytic cells for CO2 electro-reduction have recently gained traction due to reduced reactor fouling and flooding rates. However, there is still limited understanding of mass transport, electrochemical interactions, and simultaneous optimization of microfluidic cell performance metrics, such as current density, Faradaic efficiency, and CO2 conversion. This study employed COMSOL Multiphysics 5.3a to develop a steady-state numerical 2D model of microfluidic cell for electroreduction of CO2 to HCOOH and compared the optimized performance of 2 electrolytes. Specifically, this work examined the influence of [EMIM][BF4] (1-ethyl-3-methyl imidazolium tetra-fluoroborate) and [EMIM][CF3COOCH3] (1-ethyl-3-methylimidazolium tri-fluoroacetate) ionic liquid electrolytes on current density, Faradaic efficiency, and CO2 conversion. The analysis showed that a 0.9:0.1 Bi-Sn catalyst weight ratio exhibited the highest CO2 consumption per pass in the cathode gas channel. The model achieved a peak HCOOH current density of 183.8 mA cm−2, Faradaic efficiency of 87% (average of 66%), and CO2 conversion of 31.96% at −4 V compared to a standard hydrogen electrode in a microfluidic cell. Furthermore, parametric studies were conducted to determine the best input parameter for cell optimization.

The concentration of CO2 in the atmosphere has recently exceeded 420 ppm and continues to rise, mainly because of the combustion of fossil fuels, contributing significantly to climate change. CO2 capture, utilization and storage has become recognized as a critical approach to reducing energy and industrial emissions. CO2 utilization through the electrochemical reduction route is a novel alternative to CO2 storage. Microfluidic electrolytic cells for CO2 electro-reduction have recently gained traction due to reduced reactor fouling and flooding rates. However, there is still limited understanding of mass transport, electrochemical interactions, and simultaneous optimization of microfluidic cell performance metrics, such as current density, Faradaic efficiency, and CO2 conversion. This study employed COMSOL Multiphysics 5.3a to develop a steady-state numerical 2D model of microfluidic cell for electroreduction of CO2 to HCOOH and compared the optimized performance of 2 electrolytes. Specifically, this work examined the influence of [EMIM][BF4] (1-ethyl-3-methyl imidazolium tetra-fluoroborate) and [EMIM][CF3COOCH3] (1-ethyl-3-methylimidazolium tri-fluoroacetate) ionic liquid electrolytes on current density, Faradaic efficiency, and CO2 conversion. The analysis showed that a 0.9:0.1 Bi-Sn catalyst weight ratio exhibited the highest CO2 consumption per pass in the cathode gas channel. The model achieved a peak HCOOH current density of 183.8 mA cm−2, Faradaic efficiency of 87% (average of 66%), and CO2 conversion of 31.96% at −4 V compared to a standard hydrogen electrode in a microfluidic cell. Furthermore, parametric studies were conducted to determine the best input parameter for cell optimization.

The approach of integrating demand response strategy with operational scheduling is used to investigate the flexibility in the operational performance under time-sensitive electricity tariffs and to provide cost benefits analysis to the industrial consumers. The proposed approach focused on implementing a demand response strategy in a case study of scheduling for an industrial network of compressors for Time of Use and Enhanced Time of Use tariffs for heavy industries. The optimisation framework was developed as a mixed integer linear programming model. The percentage of total cost reduction is around 5% to 13% by implementing a demand response program. A considerable percentage of cost saving is possible to achieve for the Enhanced Time of use tariff since it offers an extensive off-peak time zone during the night hours and on the weekend. It is concluded that the study highlights the operational performance goal of achieving cost savings by implementing a demand response strategy for energy industries.

The approach of integrating demand response strategy with operational scheduling is used to investigate the flexibility in the operational performance under time-sensitive electricity tariffs and to provide cost benefits analysis to the industrial consumers. The proposed approach focused on implementing a demand response strategy in a case study of scheduling for an industrial network of compressors for Time of Use and Enhanced Time of Use tariffs for heavy industries. The optimisation framework was developed as a mixed integer linear programming model. The percentage of total cost reduction is around 5% to 13% by implementing a demand response program. A considerable percentage of cost saving is possible to achieve for the Enhanced Time of use tariff since it offers an extensive off-peak time zone during the night hours and on the weekend. It is concluded that the study highlights the operational performance goal of achieving cost savings by implementing a demand response strategy for energy industries.