Hong Kong Productivity Council

Luo Y., Wu Y., Li B., Mo T., Li Y., Feng S., Qu J., Chu P.K.

• Progress of fuel cell technologies in the automobile industry is summarized. • Current status and marketing of fuel cell electric vehicles (FCEVs) are reviewed. • Hydrogen FCEVs are technically feasible for the preliminary commercialization. • Hybridization with a battery system will boost the dynamic response of FCEVs. • Challenges for commercialization of FCEVs and future outlook are discussed. The automotive industry consumes a large amount of fossil fuels consequently exacerbating the global environmental and energy crisis and fuel cell electric vehicles (FCEVs) are promising alternatives in the continuous transition to clean energy. This paper summarizes the recent development of fuel cell technologies from the perspectives of the automobile industry and discusses current bottlenecks hindering commercialization of FCEVs. Current status of the fuel cell technology, policies and market prospect of FCEVs, as well as recent progress of FCEVs are reviewed. Polymer electrolyte membrane fuel cells constitute the mainstream and most mature fuel cell technology for automobile applications. Hybridization with an auxiliary battery system will greatly boost the dynamic response of FCEVs. Hydrogen FCEVs have entered the preliminary commercialization stage since 2015 and the market share of FCEVs is expected to grow at a high rate. Challenges encountered by commercialization of FCEVs and future outlook are also discussed. Future efforts are expected to focus on solving problems such as the high cost of fuel cell stack production and maintenance, insufficient hydrogen supply facilities, insufficient reliability, slow cold start, safety concerns, and immature energy management systems of FCEVs. This review serves as a reference and guide for future technological development and commercialization of FCEVs.

Liu W., Feng J., Wei T., Liu Q., Zhang S., Luo Y., Luo J., Liu X.

Aqueous rechargeable Zn—gas batteries are regarded as promising energy storage and conversion devices due to their high safety and inherent environmental friendliness. However, the energy efficiency and power density of Zn—gas batteries are restricted by the kinetically sluggish cathode reactions, such as oxygen evolution reaction (OER) during charging and oxygen reduction reaction (ORR)/carbon dioxide reduction reaction (CO2RR)/nitrogen reduction reaction (NRR)/nitric oxide reduction reaction (NORR) during discharge. In this review, battery configurations and fundamental reactions in Zn—gas batteries are first introduced, including Zn—air, Zn-CO2, Zn-N2, and Zn-NO batteries. Afterward, recent advances in active site engineering for enhancing the intrinsic catalytic activities of cathode catalysts are summarized. Subsequently, the structure and surface regulation strategies of cathode materials for optimizing the three-phase interface and improving the performance of Zn—gas batteries are discussed. Finally, some personal perspectives for the future development of Zn—gas batteries are presented.

Mo T., Li Y., Lau K., Poon C.K., Wu Y., Luo Y.

In response to severe environmental and energy crises, the world is increasingly focusing on electric vehicles (EVs) and related emerging technologies. Emerging technologies for EVs have great potential to accelerate the development of smart and sustainable transportation and help build future smart cities. This paper reviews new trends and emerging EV technologies, including wireless charging, smart power distribution, vehicle-to-home (V2H) and vehicle-to-grid (V2G) systems, connected vehicles, and autonomous driving. The opportunities, challenges, and prospects for emerging EV technologies are systematically discussed. The successful commercialization development cases of emerging EV technologies worldwide are provided. This review serves as a reference and guide for future technological development and commercialization of EVs and offers perspectives and recommendations on future smart transportation.

Qiao Y., Zheng Z., Yang H., Long J., Han P.

Medium-manganese (Mn) steel (MMS) has remarkable characteristics of high strength, strong work-hardening capacity, and wear resistance, being a promising third-generation advanced high-strength steel with lower raw material cost compared with other generations of advanced high-strength steel. The chemical composition and processing route play critical roles in determining the microstructural evolution of the MMS, and the microstructure composition significantly influences the mechanical, corrosion and wear properties of the steel. Hence, a lot of research work focus on exploring the direct relation between microstructural evolution and mechanical/corrosion/wear properties, and the progress has the following crucial aspects: (1) alloying design on the phase composition and carbide precipitation, (2) processing route on regulating microstructure evolution and twinning-induced plasticity and/or transformation-induced plasticity strengthening mechanism, (3) work-hardening, corrosion, and corrosion resistance of the regulated MMS, and (4) fracture and failure mechanism of MMS under tensile, corrosion and wear damages, as well as the improvement strategies.

Yang H., Ng B.C., Yu H.C., Liang H.H., Kwok C.C., Lai F.W.

A series of sandwich hybrid metal (steel, aluminum) + carbon, glass fiber reinforcement plastic composite (CFRP, GFRP) + metal composite sheet was developed to achieve the lightweight design purpose. It was found that the CFPR and GFRP played an important role in reducing the density of the composite sheet up to 30%, as well as maximum 30% improvement of the specific strength. The bridging mechanism found in development of hybrid sheet attributed from CF and GF delayed the composite sheet fracture, which shall improve the safety for automotive components. This result offers new insights on design and processing of metal + fiber reinforcement plastic composite sheet for lightweight design. The developed sandwich hybrid sheet with metallic sheet surface and plastic/composite sheet mid-layer to provide lightweight application.

Zheng Z., Yang H., Shatrava A.P., Long J., Wang Y., Li J., Zheng K.

The alloying of high-manganese steel with aluminum produces wear-resistant casting components with greater yield strength and significantly reduced density, which facilitates considerable energy-savings and service life extension in cement, mining, and construction operations. However, the strengthening mechanism of Al alloying responsible for the increasing yield strength, and how the fracture mechanism influences the work hardening behavior of these castings require further clarification. The present work addresses these issues by evaluating the work hardening behavior and fracture mechanisms of casting Fe–18Mn-1.3C–2Cr steels with Al alloying concentrations of 0, 4, 7, and 11 wt%. The results reveal that work hardening is facilitated by twinning-dislocation cell intersection in the absence of Al, by deformation band-planar slipping dislocation intersections et al. concentrations of 4 and 7 wt%, and by the precipitation of κ carbides at an Al concentration of 11 wt%. Furthermore, the tensile fracture mode increasingly varied from ductile fracture at 0 Al wt.% to brittle rupture at 11 Al wt.%, which was also accompanied by large voids and cleavages.

Qiao X., Zhang L., Qiu Z., Wang L., Wu Y., Deng C., Su J., Zhang X., Wang Y., Li B., Zhou L., Ma A.Y., Zhuang W., Yu K.

The anaerobic ammonium oxidation (anammox) by autotrophic anaerobic ammonia-oxidizing bacteria (AnAOB) is a biological process used to remove reactive nitrogen from wastewater. It has been repeatedly reported that elevated nitrite concentrations can severely inhibit the growth of AnAOB, which renders the anammox process challenging for industrial-scale applications. Both denitrifying (DN) and dissimilatory nitrate reduction to ammonium (DNRA) bacteria can potentially consume excess nitrite in an anammox system to prevent its inhibitory effect on AnAOB. However, metabolic interactions among DN, DNRA, and AnAOB bacteria under elevated nitrite conditions remain to be elucidated at metabolic resolutions. In this study, a laboratory-scale anammox bioreactor was used to conduct an investigation of the microbial shift and functional interactions of AnAOB, DN, and DNRA bacteria during a long-term nitrite inhibition to eventual self-recovery episode. The relative abundance of AnAOB first decreased due to high nitrite concentration, which lowered the system’s nitrogen removal efficiency, but then recovered automatically without any external interference. Based on the relative abundance variations of genomes in the inhibition, adaptation, and recovery periods, we found that DN and DNRA bacteria could be divided into three niche groups: type I (types Ia and Ib) that includes mainly DN bacteria and type II and type III that include primarily DNRA bacteria. Type Ia and type II bacteria outcompeted other bacteria in the inhibition and adaptation periods, respectively. They were recognized as potential nitrite scavengers at high nitrite concentrations, contributing to stabilizing the nitrite concentration and the eventual recovery of the anammox system. These findings shed light on the potential engineering solutions to maintain a robust and efficient industrial-scale anammox process.

Hu S., Zheng Z., Yang W., Yang H.

Aluminum (Al) containing Fe-Mn-C-Al steel exhibits both lightweight properties and outstanding mechanical properties, bringing considerable applications in vehicle, airplane, and mining industries as structural materials and components. The addition of C and Al elements into Fe-Mn iron matrix, following with subsequent heat treatment, plays an important role in microstructure controlling, such as single phase (austenite structure), or duplex phases (mixing with ferritic and austenite) matrix, as well as the short range order (SRO) and κ-carbide precipitation. These microstructural evolutions make considerable influences on mechanical properties of low density steel, especially of the work hardening, tribological, cryogenic and hydrogen embrittlement performance. The current paper introduces the progress of alloying and heat treatment, as well as the subsequent heat treatment effects on microstructural evolution and mechanical properties of Al-containing low density steel. The recent research progress of Al containing low density steel shall provide valuable source of ideas for high quality low density steel design and engineering applications. This article is protected by copyright. All rights reserved.

Mo T., Lau K., Li Y., Poon C., Wu Y., Chu P.K., Luo Y.

Road vehicles are responsible for air pollution in Hong Kong, and electric vehicles (EVs) are a promising alternative to internal combustion engine vehicles as the city is transitioning to clean energy. In this work, EV adoption in Hong Kong is investigated and analyzed, including the global EV markets, present EV status in Hong Kong, local challenges facing EV development, suggestions for EV promotion in Hong Kong, emerging technologies, and decommissioning of batteries and EVs. The challenges of EVs include insufficient charging infrastructures, inadequate management of public charging facilities, difficulties in EV repair and maintenance, “dead mileage” during charging, unacceptable long charging times, and limited commercial EV models. Strategies such as providing incentives and bonuses for commercial EVs, offering high-power quick-charging facilities, actively developing commercial EVs, installing more charging infrastructures for private EVs, building connections among stakeholders, encouraging the participation of the private sector to promote fee-based services, and supporting the development of innovative technologies should be implemented to promote EVs in Hong Kong. Emerging technologies for EVs such as wireless charging, smart power distribution, vehicle-to-grid and vehicle-to-home systems, connected vehicles, and self-driving are discussed. Eco-friendly decommissioning of EV batteries can be realized by recycling and second-life applications. This paper serves as a reference and guide for the sustainable and smart evolution of the transportation sector in Hong Kong and other global large cities.

Zhou Y., Zheng S.

Due to considerable carbon emissions in building sectors, sustainability transformation is essential for power supply reliability, stability, grid-friendly interaction, and integration with e-transportation. However, building sustainability transformation requires inter-disciplinary and trans-disciplinary platforms for ‘material-component-building-district’ co-simulations and innovations. In this study, a generic methodology is proposed to comprehensively interconnect nano-scale material and energy systems in thermal transport and thermodynamics, guiding the design and operation for lifecycle sustainability, together with carbon intensity quantification and decarbonisation potential. Afterwards, a cross-scale energy simulation platform is formulated, involving nanoporous materials, innovative components, building integrations, and district energy analytics. The formulated platform can enable synthetical and comprehensive analysis on thermodynamic performances, energy performances, energy conversion and management, throughout integrated cross-disciplinary approaches by overcoming performance overestimation or underestimation of traditional single-stage approaches. The application of the platform quantifies the decreasing magnitude of energy consumption for PCM microcapsule wall, self-cleaning façade coating, clear thermal resistant cleaning glass coating, evaporative cooling & solar PV roof, volatile organic compound (VOC) absorption for indoor air quality (IAQ) control, building integrated photovoltaics (BIPVs), solar thermal collectors and 10-kW wind turbine. Afterwards, dynamic interaction between real buildings and digital twin models was realized for fast computation and prediction, labour cost and initial investment cost saving, long-term performance analysis. Both historical database and digital twin-generated database can promote the development of machine learning (ML) models, through data preparation, hyperparameter optimization, model training, testing, and validation. The proposed approach and formulated platform can enable synthetical and comprehensive analysis on building sustainability, throughout integrated cross-disciplinary approaches for 2060 carbon neutrality in China.