• Energy Research

Resource accounting is widely practiced to identify opportunities for improving the sustainability of industrial systems. This paper presents a conceptual method for resource accounting in factories that is based on the fundamentals of thermodynamics. The approach uses exergy analysis and treats the factory as an integrated energy system comprising a building, its technical building services and manufacturing processes. The method is illustrated with a case study of an automotive cylinder head manufacturing line in which the resource efficiency of this part of the factory is analysed for different energy system options relating to heating ventilation and air conditioning. Firstly, the baseline is compared with the use of a solar photovoltaic array to generate electricity, and then a heat recovery unit is considered. Finally, both of these options are used together, and here it was found that the non-renewable exergy supply and exergy destruction are reduced by 51.6% and 49.2% respectively. Also, it was found that a conventional energy analysis would overestimate the resource savings from reducing the hot water supplied to the heating system, since energy analysis cannot account for energy quality. Since exergy analysis accounts for both energy quality and quantity it produces a different result. The scientific value of this paper is that it presents an exergy-based approach for factory resource accounting, which is illustrated through application to a real factory. The exergy-based approach is shown to be a valuable complement to energy analysis, which could lead to a more resource efficient system design than one based on energy analysis alone.

Solar cells are considered as one of the prominent sources of renewable energy suitable for large-scale adoption\ud in a carbon-constrained world and can contribute to reduced reliance on energy imports, whilst improving the\ud security of energy supply. A new arrival in the family of solar cells technologies is the organic-inorganic halide\ud perovskite. The major thrust for endorsing these new solar cells pertains to their potential as an economically\ud and environmentally viable option to traditional silicon-based technology. To verify this assertion, this paper\ud presents a critical review of some existing photovoltaic (PV) technologies in comparison with perovskitestructured\ud solar cells (PSCs), including material and performance parameters, production processes and\ud manufacturing complexity, economics, key technological challenges for further developments and current\ud research efforts. At present, there is limited environmental assessment of PSCs and consequently, a\ud methodologically robust and environmentally expansive lifecycle supply chain assessment of two types of\ud PSC modules A and B is also undertaken within the context of other PV technologies, to assess their potential for\ud environmentally friendly innovation in the energy sector. Module A is based on MAPbX3 perovskite structure\ud while module B is based on CsFAPbX3 with improved stability, reproducibility and high performance efficiency.\ud The main outcomes, presented along with sensitivity analysis, show that PSCs offer more environmentally\ud friendly and sustainable option, with the least energy payback period, as compared to other PV technologies.\ud The review and analysis presented provide valuable insight and guidance in identifying pathways and windows\ud of opportunity for future PV designs towards cleaner and sustainable energy production.

The northern part of the globe is dominated by industrialisation and is well-developed. For many years, the southern part of the world (South Asia, Africa etc.) has been a target of research concentrating on access to energy (mainly electricity) in rural regions. However, the Central Asian region has not been a focus of energy research compared to South East Asia and Africa. Despite plentiful domestically available energy resources, the energy supply in Central Asia is very unevenly distributed between urban and rural areas. Almost half of the total population of Central Asia lives in rural areas and there is a lack of access to modern energy services to meet primary needs. To analyse the energy situation (i.e., electricity, heating, hot water consumption, cooking, etc.) in rural Central Asia, this paper reviews residential energy consumption trends in rural Central Asian regions as compared to urban areas. Furthermore, the paper illustrates the potential of renewable energies in Central Asia. To perform the study, a qualitative comparative analysis was conducted based on a literature review, data, and statistical information. In summary, the presented article discusses the rural energy situation analytically and provides in-depth insights of Central Asian energy infrastructure.

Jaggery is a non-traditional sweetener that is produced from boiling sugarcane juice. Due to the energy intensive nature of the combustion process in jaggery making, previous studies in literature have presented various process and equipment modifications to affect its energy efficiency. This study adds to the understanding of the resource transformations and consumptions in the jaggery process by presenting its exergy analysis. The baseline process was operationally modified for which the exergy efficiency and exergy destruction are calculated. Through the modifications, the exergy efficiency and exergy destruction increased by 11.2% and 0.8% respectively. A significant amount of exergy was wasted as surplus heat in the form of flue gas, which reduced by 11.5% due to process modifications. The results show that while the most evident form of resource waste was due to flue gas released into the environment, the largest form of resource consumption was actually due to exergy destruction arising from irreversibilities in combustion, a result not clearly evident through energy analysis alone. Through modelling process flows in terms of exergy, the analysis presented in this paper increases the visibility of the resource consumptions and losses in the jaggery making process. This study should aid the efforts of researchers and practitioners aiming to reduce resource consumption in the jaggery making process. Keywords: Exergy analysis, Energy analysis, Resource flows mapping, Resource consumption, Resource efficiency, Resource efficient manufacturing, Energy reuse

Global awareness of environmental impacts such as climate change and depletion of ozone layer has increased significantly in the last few years and the implication for emissions reductions in buildings are widely acknowledged. The goal, therefore, is to design and construct buildings with minimum environmental impacts. Lifecycle emissions resulting from buildings consist of two components: operational and embodied emissions. A great deal of effort has been put into reducing the former as it is assumed that it is higher than the latter. However, studies have revealed the growing significance of embodied emissions in buildings but its importance is often underestimated in lifecycle emissions analysis. This paper takes a retrospective approach to critically review the relationship between embodied and operational emissions over the lifecycle of buildings. This is done to highlight and demonstrate the increasing proportion of embodied emissions that is one consequence of efforts to decrease operational emissions. The paper draws on a wide array of issues, including complications concerning embodied emissions computation and also discusses the benefits that come with its consideration. The implication of neglecting embodied emissions and the need for an urgent policy framework within the current climate of energy and climate change policies are also discussed.

Exergy analysis has widely been used to assess resource consumption, and to identify opportunities for improvement within manufacturing. The main advantages of this method are its ability to account for energy quality and consumption. However, its application in industrial practice is limited, which may be due to the lack of its consistent application in practice. Current energy management standard, that facilitate consistent application of procedures do not consider the quality aspects of energy flows. An exergy based energy management standards is proposed in this paper that would take into account energy quality aspects, while facilitating the consistent application of exergy analysis in industrial practice. Building on ISO50001, this paper presents guidelines for implementing energy and resource management in factories, incorporating the concepts of exergy and holistic factory simulation, as illustrated through a manufacturing case study. From the factory level analysis, a chilling process was identified to have significant improvement potential. A dry fan cooler, using ambient air was proposed for the improved efficiency of the chillers. Energy based metrics portrayed a system that operated at high efficiency, however exergy analysis indicated much room for further improvement, therefore impacting decision making for technology selection. The contribution of this paper is in presenting a set of prescriptive guidelines that could possibly be further developed into a new energy management standard that would utilize the advantages of exergy analysis towards improved energy and resource management in manufacturing.

Abstract The paper describes an experimental study from forty-eight subjects about the acceptable thermal conditions under three ventilation strategies with six exhaust configurations, including mixing ventilation (MV), displacement ventilation (DV), and four exhaust types of stratum ventilation (ceiling-level-exhausted “SV”, rear-low-level-exhausted “SV-1”, front-low-level-exhausted “SV-2” & rear-middle-level-exhausted “SV-3”) serving a confined 8.8 m × 5.1 m × 2.4 m (h) classroom. Tests were carried out in a specially constructed test chamber designed to represent a typical small-medium sized classroom in Hong Kong. Thermal comfort analyses were carried out under specific supply flow rates, room temperatures, and air speeds in three ventilation strategies with six exhaust configurations. From the collected data, SV at 26 °C & 10 ACH and SV-3 at 28 °C & 15 ACH are achieved 100% of acceptable vote, the highest percentage of 97.3%, scoring neutral (0), are under the SV-3 at 28 °C & 10 ACH. The thermal satisfaction acceptance percentage in stratum ventilation strategies can be improved by increasing the air flow supply from 10 to 15 ACH at the elevated indoor condition of 26.8 °C, 27.3 °C and 26.4 °C by SV, SV-1 and SV-3 respectively, but not under MV, DV and SV-2. It implies that the thermal comfort will be affected no only by the temperature and air supply flow, but also by difference ventilation strategies in this study of three ventilation strategies with six exhaust configurations. This result indicates that SV-3 can satisfy human perception of comfort with least value of energy consumption, due to higher neutral temperature in comparison with the other ventilation strategies.