| 1. |
- Nazir, Shareq Mohd, et al.
(author)
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Efficient hydrogen production with CO2 capture using gas switching reforming
- 2019
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In: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 185, s. 372-385
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Journal article (peer-reviewed)abstract
- Hydrogen is a promising carbon-neutral energy carrier for a future decarbonized energy sector. This work presents process simulation studies of the gas switching reforming (GSR) process for hydrogen production with integrated CO2 capture (GSR-H2 process) at a minimal energy penalty. Like the conventional steam methane reforming (SMR) process, GSR combusts the off-gas fuel from the pressure swing adsorption unit to supply heat to the endothermic reforming reactions. However, GSR completes this combustion using the chemical looping combustion mechanism to achieve fuel combustion with CO2 separation. For this reason, the GSR-H2 plant incurred an energy penalty of only 3.8 %-points relative to the conventional SMR process with 96% CO2 capture. Further studies showed that the efficiency penalty is reduced to 0.3 %-points by including additional thermal mass in the reactor to maintain a higher reforming temperature, thereby facilitating a lower steam to carbon ratio. GSR reactors are standalone bubbling fluidized beds that will be relatively easy to scale up and operate under pressurized conditions, and the rest of the process layout uses commercially available technologies. The ability to produce clean hydrogen with no energy penalty combined with this inherent scalability makes the GSR-H2 plant a promising candidate for further research
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| 2. |
- Nazir, Shareq Mohd, et al.
(author)
-
Efficient hydrogen production with CO2 capture using gas switching reforming (GSR) : techno-economic assessment
- 2019
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In: Proceedings of the 32nd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS). ; , s. 635-644
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Conference paper (peer-reviewed)abstract
- Hydrogen is identified as one of the clean energy carriers in the future energy scenario. This work presents a process to produce low cost hydrogen with CO2 capture using gasswitching reforming (GSR). The process steps include GSR, water-gas shift, purehydrogen recovery in pressure-swing adsorption process and CO2 and hydrogencompression trains. The overall process, denoted as GSR-H2, produces 99.999% purehydrogen with >96% CO2 capture. In this study, GSR-H2 is compared economically with the conventional steam-methane reforming (SMR) plant that produces hydrogenwithout CO2 capture. GSR-H2 produces 10% more hydrogen when compared to theSMR plant, but consumes significant imported electricity. The cost of hydrogenproduced from the GSR-H2 and SMR plant is similar (1.67 €/kg-H2) with a CO2 tax of only 20 €/ton, even with GSR-H2 being a near zero emission plant. In a future energy scenario where the CO2 emission tax is high and the electricity price is low, GSR-H2will significantly outperform the conventional SMR plant.
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| 3. |
- Nazir, Shareq Mohd, et al.
(author)
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Gas switching reforming (GSR) for power generation with CO2 capture: Process efficiency improvement studies
- 2019
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In: Energy. - : Elsevier BV. - 0360-5442. ; 167, s. 757-765
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Journal article (peer-reviewed)abstract
- This paper presents the process improvement studies of a combined cycle power plant integrated with a novel gas switching reforming (GSR) process for hydrogen production with integrated CO2 capture. The overall process is denoted as GSR-CC (gas switching reforming-combined cycle). Five cases are presented in which a systematic approach was adopted to improve the net electrical efficiency of the GSR-CC process. Two cases focus on reducing the number of unit operations and the other three cases focus on heat integration. The net electrical efficiency of the base case GSR-CC process is 45.8% whereas the improved GSR-CC has a net electrical efficiency of 51.1%. The efficiency penalty in the improved GSR-CC process is only 7.2 %-points with respect to the reference case natural gas combined cycle power plant without CO2 capture, and is less than post-combustion capture methods presented in literature. The CO2 avoidance in the GSR-CC is more than 95%. GSR-CC also gives a flexibility in the output from the plant in terms of pure H-2 or electricity and the optimal plant configuration is designed to maximize this flexibility.
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| 4. |
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| 5. |
- Nazir, Shareq Mohd, 1986-, et al.
(author)
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Pathways to low-cost clean hydrogen production with gas switching reforming
- 2021
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In: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 46:38, s. 20142-20158
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Journal article (peer-reviewed)abstract
- Gas switching reforming (GSR) is a promising technology for natural gas reforming with inherent CO2 capture. Like conventional steam methane reforming (SMR), GSR can be integrated with water-gas shift and pressure swing adsorption units for pure hydrogen production. The resulting GSR-H2 process concept was techno-economically assessed in this study. Results showed that GSR-H2 can achieve 96% CO2 capture at a CO2 avoidance cost of 15 $/ton (including CO2 transport and storage). Most components of the GSR-H2 process are proven technologies, but long-term oxygen carrier stability presents an important technical uncertainty that can adversely affect competitiveness when the material lifetime drops below one year. Relative to the SMR benchmark, GSR-H2 replaces some fuel consumption with electricity consumption, making it more suitable to regions with higher natural gas prices and lower electricity prices. Some minor alterations to the process configuration can adjust the balance between fuel and electricity consumption to match local market conditions. The most attractive commercialization pathway for the GSR-H2 technology is initial construction without CO2 capture, followed by simple retrofitting for CO2 capture when CO2 taxes rise, and CO2 transport and storage infrastructure becomes available. These features make the GSR-H2 technology robust to almost any future energy market scenario.
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| 6. |
- Nazir, Shareq Mohd, et al.
(author)
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Techno-economic Comparison Of Combined Cycle Power Plants With Pre-combustion CO2 Capture Via Two Different Reforming Methods: Chemical Looping Reforming And Gas Switching Reforming
- 2018
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Conference paper (peer-reviewed)abstract
- This paper focuses on the techno-economic comparison of gas-fired combined cycle power plants with CO2 capture and tworeforming methods, chemical looping reforming (CLR) and gas-switching reforming (GSR). The overall processes are denoted asCLR-CC and GSR-CC respectively. The net electrical efficiency of the CLR-CC and GSR-CC is 42.1% and 46.2% respectively.Anyhow, with improvements in the gas turbine configuration, the net electrical efficiency improves by 2.5%. GSR-CC has ahigher CO2 avoidance (>95%). The levelised cost of electricity (LCOE) for CLR-CC is lower than that of GSR-CC for basedload operation of the power plant. Anyhow, GSR-CC provides flexibility in terms of output, electricity or pure H2. The capitalrequirement in the GSR-CC is higher due to the requirement of multiple standalone reactors to maintain a steady flow of thesyngas produced from the GSR. The LCOE of both the processes is sensitive to the fuel cost. Further improvements in the GSRCCprocess can make the process competitive to post-combustion capture.
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| 7. |
- Ugwu, Ambrose, et al.
(author)
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Gas switching technology : Economic attractiveness for chemical looping applications and scale up experience to 50 kW(th)
- 2022
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In: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836 .- 1878-0148. ; 114
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Journal article (peer-reviewed)abstract
- Gas switching technology (GST) was introduced to facilitate operation and scale-up of pressurized chemical looping-based technologies thus bringing the expected benefits of reducing costs and energy penalty of CO2 capture. GST has so far been applied to generate heat/power, hydrogen, syngas, and oxygen using fossil fuel gas (but also from biomass for negative CO2 emissions) with integrated CO2 capture at minimal energy penalty generating over 50 publication studies demonstrating the technical feasibility of the technology and quantifying the potential energy and cost savings. In contrast to conventional chemical looping, GST inherently avoids solids circulation by alternating oxidizing and reducing conditions into a single fluidized bed reactor with an oxygen carrier, thus removing many of the technical challenges that hinder the scale-up of the technology. GST has successfully been applied and demonstrated for combustion, steam/dry methane reforming, and water splitting, using different oxygen carriers, showing the ease of operation under both atmospheric and pressurized conditions and achieving high products separation efficiency.This paper summarises the different studies completed on the Gas Switching Technology covering experimental demonstration (including the experience from a 50 kW(th) cluster), process modelling and techno-economics, highlighting the advantages and disadvantages of the technology and discussing the way forward.
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| 8. |
- Bonato, Maud, et al.
(author)
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Growth rate and hatching date in ostrich chicks reflect humoral but not cell-mediated immune function
- 2009
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In: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 1432-0762 .- 0340-5443. ; 64:2, s. 183-191
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Journal article (peer-reviewed)abstract
- A tradeoff between immune response and life history traits, in particular growth rate, has been documented in various bird species. Ostriches are fast-growing birds and a typical feature of cohorts is that offspring often differ greatly in size. We investigated the relationship between hatching date and growth rate of chicks and both cell-mediated (measured using a phytohaemagglutinin (PHA) injection) and humoral immune responses in ostrich chicks maintained on a research farm. Chicks with higher growth rates had intermediate responses to both diphtheria and tetanus toxoids. By contrast, no relation between growth rates and responses to PHA injection were found. We conclude that chick growth rate variation may be explained beyond a certain threshold by a tradeoff between the humoral response and growth. Both responses to PHA injection and humoral responses in chicks were found to decrease with chick hatching date. Within the context of ostrich farming, these results could partially explain size variations observed in cohorts of chicks, as well as high mortality rates during their first 3 months of age.
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| 9. |
- Bonato, Maud, et al.
(author)
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Ostrich chick humoral immune responses and growth rate are predicted by parental immune responses and paternal colouration
- 2013
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In: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 1432-0762 .- 0340-5443. ; 67:12, s. 1891-1901
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Journal article (peer-reviewed)abstract
- One of the most important measures of offspring performance is growth rate, which is often traded off against another important survival trait, immune function. A particular feature of ostrich chicks maintained in farmed environments is that cohorts of chicks vary widely in size. As parents can have a profound effect on the phenotype and fitness of their offspring, we investigated whether chick growth and immune defence were related to variation in levels of immune defence in their genetic parents. As secondary sexual traits of sires could serve as indicators of male quality, and be used in female mating decisions, we also investigated whether chick growth rate and immune defence were related to male plumage and integumentary colouration. We found that offspring growth rates and humoral responses were related to the humoral responses of their parents, suggesting that at least some components of humoral immune capacity are heritable. The white colour of male ostrich feathers was correlated to the humoral response and growth rate of their offspring, suggesting that this visual cue involved in the male courtship display could serve as an important signal to females of male quality, thereby forming the basis of mate choice in this species.
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| 10. |
- Bonato, Maud, et al.
(author)
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Predicting ejaculate quality and libido in male ostriches: Effect of season and age.
- 2014
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In: Animal Reproduction Science. - : Elsevier BV. - 1873-2232 .- 0378-4320. ; 151:1-2, s. 49-55
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Journal article (peer-reviewed)abstract
- The success of artificial breeding program depends largely on the reproductive performance of males. Male performance can vary with season and age impacting on quality and quantity of semen collected for artificial insemination purposes and therefore fertility of inseminated females. We examined variation in semen output and male libido of seven male ostriches (aged 2-5 years) over a period of 24 months. We collected ejaculates using a dummy female and measured semen characteristics (ejaculate volume, sperm concentration, number of spermatozoa per ejaculate, sperm motility and morphology) and male libido (willingness to mount the dummy). A total of 1006 ejaculates were collected. Across months, the volume of semen (mean±SEM) ranged from 1.03±0.12mL to 1.85±0.07mL, the sperm concentration from 3.21±0.12×10(9)/mL to 4.16±0.74×10(9)/mL, and the number of spermatozoa from 3.42±0.28×10(9) to 7.66±0.47×10(9). The largest volume of ejaculates and the highest number of sperm were collected in spring. Ejaculates with higher number of normal sperm were also collected in spring-early summer, whereas ejaculates with higher numbers of live abnormal and dead sperm were collected in winter. Sperm motility was relatively constant over months, despite a reduction in summer (January-February), while male libido peaked in winter (June-July) and spring (October-November). Furthermore, we observed high individual variation between males for all variables tested, except for motility. These results indicate that collections conducted in spring yield higher number of spermatozoa, when the libido of males is also at a maximum. Therefore in this species seasonal variation in semen quality should be considered in breeding programmes by artificial insemination to maximise fertility.
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