可再生能源在香港的应用前景

分析了香港的能源和环境的现状和形势，并结合香港的气候特点，提出了利用香港的可再生能源缓解香港日益严峻的能源问题和环境污染问题。并初步分析了各种可再生能源的基本发展状况和利用前景，对今后香港的能源发展和结构调整具有一定的参考意义。     

A discussion on potentials of saving energy use for commercial buildings in Hong Kong

A typical commercial building was selected for a detailed study of energy use by mechanical ventilation and air-conditioning (MVAC) systems. Data from preliminary building energy auditing were analyzed and compared with the energy use of other similar buildings. Correlation relationships between the building envelope heat gain and the electrical energy use for MVAC system with key parameters were derived with approaches similar to the Princeton Scorekeeping Method (PRISM). Further, the energy simulation program TRACE 600 was used to justify the results. A total of 20 energy-saving measures were investigated for possible use in local commercial buildings. The results provided are useful for engineers in designing energy-efficient commercial buildings or generating new design concepts for better MVAC systems.     

Potential of renewable hydrogen production for energy supply in Hong Kong

Hong Kong is highly vulnerable to energy and economic security due to the heavy dependence on imported fossil fuels. The combustion of fossil fuels also causes serious environmental pollution. Therefore, it is important to explore the opportunities for clean renewable energy for long-term energy supply. Hong Kong has the potential to develop clean renewable hydrogen energy to improve the environmental performance. This paper reviews the recent development of hydrogen production technologies, followed by an overview of the renewable energy sources and a discussion about potential applications for renewable hydrogen production in Hong Kong. The results show that although renewable energy resources cannot entirely satisfy the energy demand in Hong Kong, solar energy, wind power, and biomass are available renewable sources for significant hydrogen production. A system consisting of wind turbines and photovoltaic (PV) panels coupled with electrolyzers is a promising design to produce hydrogen. Biomass, especially organic waste, offers an economical, environmental-friendly way for renewable hydrogen production. The achievable hydrogen energy output would be as much as 40% of the total energy consumption in transportation.     

An analysis of future building energy use in subtropical Hong Kong

Principal component analysis of prevailing weather conditions in subtropical Hong Kong was conducted, and a new climatic index Z (as a function of the dry-bulb temperature, wet-bulb temperature and global solar radiation) determined for past (1979–2008, measurements made at local meteorological station) and future (2009–2100, predictions from general circulation models) years. Multi-year (1979–2008) building energy simulations were carried out for a generic office building. It was found that Z exhibited monthly and seasonal variations similar to the simulated cooling/heating loads and building energy use. Regression models were developed to correlate the simulated monthly building cooling loads and total energy use with the corresponding Z. Error analysis indicated that annual building energy use from the regression models were very close to the simulated values; the difference was about 1%. Difference in individual monthly cooling load and energy use, however, could be up to 4%. It was also found that both the DOE-simulated results during 1979–2008 and the regression-predicted data during 2009–2100 indicated an increasing trend in annual cooling load and energy use and a gradual reduction in the already insignificant heating requirement in cooling-dominated office buildings in subtropical climates.     

Analysis of embodied energy use in the residential building of Hong Kong

Energy use in buildings accounts for nearly half of the total primary energy use in Hong Kong. Until now, studies have primarily focused on energy conservation in building operation, even though recent research has indicated that the embodied energy used in residential buildings could account for up to 40% of the life-cycle energy used in residential buildings. Accordingly, this paper presents a study on the energy embodied in the residential building envelope of Hong Kong. A model for estimating the intensities of the embodied and demolition energy for buildings has been developed. Two typical high-rise residential buildings, the Housing Authority Harmony 1 and the New Cruciform blocks, are analysed based on the developed model. The results of the analysis provide an insight into the embodied energy usage profile in residential buildings in Hong Kong. Energy embodied in steel and aluminium ranks as the first and second largest energy demand and may account for more than three-quarters of the total embodied energy use in a residential building envelope in Hong Kong. This reveals those building components with significant potential for reduction in embodied energy demand.     

Regulatory and voluntary approaches for enhancing energy efficiencies of buildings in Hong Kong

Regulatory control forms the bedrock of the environmental policies of many countries. Whilst this interventionist approach can ensure a certain minimum standard would be achieved, far greater results can be achieved if it is augmented by a voluntary assessment-scheme. The benefits of having both approaches are explored in the paper with reference to the building energy codes and a voluntary building environmental-performance assessment scheme HK-BEAM, both of which are being implemented in Hong Kong. Quantification of the possible range of energy saving was based on the design characteristics of 22 commercial buildings in Hong Kong. The need for and the benefits of using the energy assessments within HK-BEAM as an alternative compliance route to the building energy codes are confirmed and the compliance criteria are established. The potential energy-saving through the use of the regulatory and the voluntary-based approaches were estimated to be from about 8% to more than 30%.     

建筑节能评估软件简介

分析国内外关于建筑节能评估软件的研发现状,指出构建符合我国国情的建筑节能评估体系的必要性,在这一体系界定下,构建了以动态模拟模块和一致性评估模块为核心的建筑节能评估软件模型。     

A study of atmospheric turbidity for Hong Kong

Clear skies are important in predicting the peak solar irradiance and daylight illuminance levels for active solar energy utilisation and passive energy-efficient building designs. The clearness of a sky is affected by the clarity of the atmosphere which is usually expressed in terms of a turbidity index. This study considers two common turbidity parameters including the Linke turbidity factor (T_L) and Angstrom turbidity coefficient (β). The annual and monthly average values, frequency of occurrence and cumulative frequency distribution of individual turbidity indices based on different approaches have been established to describe the clear sky atmospheric conditions in Hong Kong. The general features and characteristics of the findings are discussed.     

Developing a Web-Based Learning Environment for Building Energy Efficiency and Solar Design in Hong Kong

With the growing importance of renewable energy and energy efficient technologies, there is an urgent need to integrate the new knowledge in these fields into our education system. The Internet and World Wide Web (WWW) can be an effective medium for the delivery of good quality education and training for these subjects, because of its flexibility, timeliness, and breadth of access. This paper investigates an approach for developing a web-based learning environment for building energy efficiency and solar design. The use of the WWW as a delivery system for educational materials and information resources is discussed. Some of the technical and pedagogical issues associated with the web-based techniques are identified. The experience from a pilot study at the University of Hong Kong is evaluated and the major considerations for the design of web-based learning are presented. It is hoped that the present study could stimulate more discussions and innovative ideas for exploiting the educational potential of the WWW for energy education.     

Hydrogen energy storage integrated hybrid renewable energy systems: A review analysis for future research directions

Hydrogen energy storage systems (HydESS) and their integration with renewable energy sources into the grid have the greatest potential for energy production and storage while controlling grid demand to enhance energy sustainability. This paper presents a bibliometric analysis based on a comprehensive review of the highly cited articles on HydESS to provide a detailed insight into future directions and applications. The study was carried out by using the Scopus database search engine to look for filtered keywords in the HydESS and related research. It can be demonstrated that the HydESS literature expanded rapidly from 2016 to 2021 compared to 2011 to 2015. It is found that 89.17% of published articles explained control and test systems-based methods, whereas 10.83% of publications discuss review assessments. Our analysis of highly cited articles on HydESS highlights several aspects, such as methods and systems, issues, difficulties, and challenges to establishing current constraints and research gaps. This evaluation can enhance operational performance, environmental friendliness, energy savings, uninterrupted power supply service, cost benefits, on-site generation, and adaptability. It would be beneficial for technology development and the growth of the hydESS industry. This study may act as a guideline not only for academics in determining the line of research and generating additional discoveries, but also for the government in formulating financial strategies.     

Impact of climate change on commercial sector air conditioning energy consumption in subtropical Hong Kong

Past and future trend of electricity use for air conditioning in the entire commercial sector in subtropical climates using 1979–2008 measured meteorological data as well as predictions for 2009–2100 from a general circulation model (MIROC3.2-H) was investigated. Air conditioning consumption showed an increasing trend over the past 30 years from 1979 to 2008. Principal component analysis (PCA) of measured and predicted monthly mean dry-bulb temperature, wet-bulb temperature and global solar radiation was conducted to determine a new climatic index Z for 1979–2008 and future 92 years (2009–2100) based on two emissions scenarios B1 and A1B (low and medium forcing). Through regression analysis, electricity use in air conditioning for the 92-year period was estimated. For low forcing, average consumption in 2009–2038, 2039–2068 and 2069–2100 would be, respectively, 5.7%, 12.8% and 18.4% more than the 1979–2008 average, with a mean 12.5% increase for the entire 92-year period. Medium forcing showed a similar increasing trend, but 1–4% more. Standard deviations of the monthly air conditioning consumption were found to be smaller suggesting possible reduction in seasonal variations in future years.     

Effect of neutral temperature on energy saving of centralized air-conditioning systems in subtropical Hong Kong

Higher room temperature can still let the occupants have a neutral thermal sensation if higher air speed is provided. With a suitable scheme of neutral temperature and comfort air speed, reduction of energy consumption of the central chiller plant may surpass the additional energy requirement of the air side equipment, then both energy saving and thermal comfort can be achieved for the entire air-conditioning system. To evaluate this, the energy consumptions of a centralized air-conditioning system using the common air side alternatives were studied for the subtropical Hong Kong. The alternatives are variable air volume (VAV) system, constant air volume (CAV) system and fan coil (FC) system. Each of them was associated to a central chiller plant to serve a high-rise office building. The studying range of the room air temperature was from 23 °C to 30 °C. It is found that the VAV and FC systems can provide both thermal comfort and energy saving for higher room temperature, but CAV system is not feasible when the room air temperature is above 27 °C. If the indoor air speed threshold is considered, the neutral temperature can be brought up to 26.5 °C, and the energy saving potentials of VAV and FC systems would be 12.9% and 9.3% respectively.     

Barriers to implement extensive green roof systems: A Hong Kong study

Air pollution problems caused from the development of infrastructures are getting serious, in which air flow is reduced and heat is trapped among high-rise buildings. In order to mitigate these problems, various methods have been developed in previous studies. Extensive green roof has been identified as one of the most important means to mitigate these problems and implement sustainable development principles in the building features. Governments world-wide have been introducing various policies and regulations for promoting extensive green roof particularly for building projects. However, the existing buildings in many large cities such as Hong Kong display few extensive green roof features. Hong Kong is one of the most densely populated cities with many high-rise buildings. This paper examines the major barriers encountered in promoting extensive green roof systems for the existing buildings in Hong Kong. Case study approach is adopted to investigate how and why the barriers can hinder the implementation of extensive green roof features. Research results show that lack of promotion and incentives from governments and the increase maintenance cost are identified as the top barriers to the implementation. The paper concludes by providing further suggestions and actions that can help mitigate these existing barriers.     

Copula-based joint distribution analysis of wind speed and wind direction: Wind energy development for Hong Kong

Accurate and reliable assessment of wind energy potential has important implication to the wind energy industry. Most previous studies on wind energy assessment focused solely on wind speed, whereas the dependence of wind energy on wind direction was much less considered and documented. In this paper, a copula-based method is proposed to better characterize the direction-related wind energy potential at six typical sites in Hong Kong. The joint probability density function (JPDF) of wind speed and wind direction is constructed by a series of copula models. It shows that Frank copula has the best performance to fit the JPDF at hilltop and offshore sites while Gumbel copula outperforms other models at urban sites. The derived JPDFs are applied to estimate the direction-related wind power density at the considered sites. The obtained maximum direction-related wind energy density varies from 41.3 W/m² at an urban site to 507.9 W/m² at a hilltop site. These outcomes are expected to facilitate accurate micro-site selection of wind turbines, thereby improving the economic benefits of wind farms in Hong Kong. Meanwhile, the developed copula-based method provides useful references for further investigations regarding direction-related wind energy assessments at various terrain regions. Notably, the proposed copula-based method can also be applied to characterize the direction-related wind energy potential somewhere other than Hong Kong.     

Hydrogen in energy transition: A review

The energy transition is not something that awaits us in the next decade. On the contrary, it is a process in which we are already deeply enrolled. The main step towards the creation of a carbon-neutral society is the implementation of renewable energy sources (RES) as replacements for fossil fuels. Given the intermittency of RES, energy storage has an essential role to play in this transition. Hydrogen technology with its many advances was recognized to be the most promising choice. As multiple hydrogen applications were researched relatively recently, the current development of its technology is not yet on the large-scale implementation level. With the increasing number of studies and initiated projects, the utilization of hydrogen's immense ecological potential is to be expected in the next few decades. New innovative solutions of hydrogen technology that includes hydrogen production, storage, distribution, and usage, are permeating all industry sectors. In a rapidly changing world, technological advances bring forth public discussions, that are a deciding factor whether society will be able to adapt and accept those new contributions or reject them. Currently, hydrogen is the best associated with fuel cell electric vehicles which emit only water vapour and warm air, producing no harmful tailpipe emissions. As various scientists are stressing the gravity of climate change effects that are reaching the physical environment, ecosystems, and humanity in general, concern for the future is becoming the main global topic. Consequently, governments are implementing new sustainable policies that promote RES as a substitute for fossil fuels. Increasing progress in hydrogen technology instigated nations worldwide to incorporate hydrogen in their energy legislations and national development plans, which resulted in numerous national hydrogen strategies. This work shows the progress of hydrogen taking its place as a key factor of the future green energy society. It reviews recent developments of hydrogen technologies, their social, industrial, and environmental standing, as well as the stage of transitioning economies of both advanced and beginner countries. An example of the ongoing energy transition is Croatia, which is in the process of implementing a hydrogen strategy with the ambition to be able to one day equally participates in the rapidly emerging hydrogen market.     

A feasible reform for the electricity supply industry in Hong Kong

With the current scheme of control regulation for the Hong Kong electricity supply industry expiring in 2008, the Government has sent out a consultation paper seeking views from the general public on its reform and possible future development. This paper investigates the characteristics of the current agreement and the rationale for feasible reform of the Hong Kong ESI. It leads to a discussion on a proposed feasible reform using performance-based regulation approach modeling and the associated implementation issues related to price capping, risk analysis, performance indices, quality monitoring and governance.     

Grid-connected building-integrated photovoltaics: a Hong Kong case study

The first building-integrated photovoltaic system (BIPV) in Hong Kong has been working successfully for three years, as remote system for the first year and grid-connected system in the last two years. A number of issues have been investigated on the experimental system including technical, economical, operation and management topics. This paper presents the findings from this research project funded by the Industrial Support Fund of the Hong Kong SAR Government. Simulation and data monitoring have been completed for energy performance of the BIPV system under Hong Kong weather conditions. The natural ventilation effect of an air gap on PV module’s power output and heat transfer across the PV wall and PV-roof have been investigated. Good agreement between simulation and experimental results was achieved. The system can provide about 41% of electric power for an indoor lighting floor area circuit of 250 m². The harmonics of the power output from the PV system was also measured to check the interference level to the utility grid. Experiments show that the total harmonics current distortion of the grid-connected BIPV system is far lower than that from some conventional equipment, such as personal computers. The total harmonics from this BIPV system is less than 12% for most of the time, even when the incident solar irradiation is very weak.     

Energy use in commercial buildings in Hong Kong

The energy performances of 20 commercial buildings, covering the common types found in Hong Kong, have been studied. The monthly electricity billing data as well as the results from computer modeling were analyzed. Energy signatures for the commercial buildings were found by a method similar to PRISM. Correlation equations of energy use with building envelope parameters, such as OTTV, building size, envelope heat gain, and the annual chiller-load were derived. The results are useful for building envelope design, energy audit, and legislative control of energy use in commercial buildings.