Solar hydrogen hybrid energy systems for off-grid electricity supply: A critical review Z. Abdin, C.J. Webb n , E.MacA. Gray Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan 4111, Brisbane, Australia article info Article history: Received 24 November 2014 Received in revised form 26 June 2015 Accepted 1 August 2015 Available online 2 September 2015 Keywords: Solar Hybrid energy system Energy vector Hydrogen production Hydrogen storage Electrolysis Fuel cell abstract Large areas in many countries are populated but have no connection to a national electricity grid. Centralised electricity generating facilities burning fossil fuels have been the norm. Renewable energy resources, especially solar/wind energy, are now penetrating this sector. Long-term energy storage is the universal challenge in providing renewables-based electricity with high availability across the seasons. Here we review and discuss the use of hydrogen as the energy vector by means of which solar/wind energy is transformed, stored and made available as electricity. The dominant system configuration is presently photovoltaic electricity used to electrolyse water to produce hydrogen, which is stored as a pressurised gas or metal-hydride, then retrieved from storage to generate electricity in a fuel cell. We survey the demonstration projects reported in the literature and discuss the need for authoritative system modelling in order to size the system components for minimum cost at a designated availability of supply. Crown Copyright & 2015 Published by Elsevier Ltd. All rights reserved. Contents 1. Introduction ....................................................................................................... 1792 2. Hydrogen as an energy vector ........................................................................................ 1792 3. The off-grid supply problem .......................................................................................... 1793 4. Solar electricity generation ........................................................................................... 1793 5. Solar hydrogen production ........................................................................................... 1794 5.1. Alternatives to water electrolysis ................................................................................ 1795 5.2. Water electrolysis ............................................................................................ 1795 6. Hydrogen storage .................................................................................................. 1796 6.1. Compressed hydrogen ......................................................................................... 1796 6.2. Physisorption ................................................................................................ 1796 6.3. Chemisorption ............................................................................................... 1797 6.3.1. Metal hydrides ........................................................................................ 1797 6.3.2. Complex hydrides ..................................................................................... 1797 7. Electricity generation from hydrogen ................................................................................... 1798 7.1. Alternatives to fuel cells ....................................................................................... 1798 7.2. Fuel cells ................................................................................................... 1798 8. Solar hydrogen hybrid energy systems.................................................................................. 1799 8.1. Prototype systems ............................................................................................ 1801 9. Optimisation and modelling .......................................................................................... 1804 10. Barriers and trends ................................................................................................. 1805 11. Summary and conclusions ........................................................................................... 1805 References ............................................................................................................ 1806 Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/rser Renewable and Sustainable Energy Reviews http://dx.doi.org/10.1016/j.rser.2015.08.011 1364-0321/Crown Copyright & 2015 Published by Elsevier Ltd. All rights reserved. n Corresponding author. Tel.: þ61 7 3735 5023; fax: þ61 7 3735 7656. E-mail address: j.webb@griffith.edu.au (C.J. Webb). Renewable and Sustainable Energy Reviews 52 (2015) 1791–1808