International Journal of Hydrogen Energy 31 (2006) 1401 – 1412 www.elsevier.com/locate/ijhydene Potential of renewable hydrogen production for energy supply in Hong Kong Meng Ni, Michael K.H. Leung ∗ , K. Sumathy, DennisY.C. Leung Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, PR China Available online 13 December 2005 Abstract 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.  2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. Keywords: Hydrogen production; Renewable energy; Renewable hydrogen 1. Introduction Using fossil fuels as the primary energy source has led to serious energy crisis and environmental pollution on a global scale. In Hong Kong, fossil fuels consumed directly for electricity generation and vehicle transporta- tion amount to 48% and 36%, respectively, of the total estimate of 290,000 TJ per year [1]. Correspondingly, about 40 million tons of greenhouse gases are emitted every year due to the combustion of fossil fuels [2]. In order to mitigate the above environmental problems, it is of paramount importance to develop clean, renewable energy sources, especially solar energy and wind power ∗ Corresponding author. Tel.: +852 2859 2628; fax: +852 2858 5415. E-mail address: mkhleung@hku.hk (M.K.H. Leung). 0360-3199/$30.00  2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2005.11.005 at competitive costs resulting from the fast technolog- ical development. The limitations of solar and wind power are site-specific, intermittent and, thus, not reli- able for instantaneous supply. Using batteries to store any energy surplus for later consumption can resolve the time mismatch between energy supply and demand. The shortcomings of battery storage are low-storage ca- pacity, short equipment life, and considerable solid and chemical wastes generated. In order to better harness renewable energy, hydro- gen has been identified as a potential alternative fuel as well as an energy carrier for the future energy sup- ply. Hydrogen is clean and, in practice, it can be pro- duced from water, which is abundant. Hydrogen is also renewable when it is produced from renewable energy sources. When it is converted into useful energy in the form of electricity via a fuel cell, the by-product is