Review An overview of renewable hydrogen production from thermochemical process of oil palm solid waste in Malaysia Seyed Ehsan Hosseini ⇑ , Mazlan Abdul Wahid, A. Ganjehkaviri High-Speed Reacting Flow Laboratory, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia article info Article history: Received 9 November 2014 Accepted 4 February 2015 Keywords: Hydrogen Palm solid residue Gasiﬁcation Pyrolysis abstract Hydrogen is one of the most promising energy carriers for the future of the world due to its tremendous capability of pollution reduction. Hydrogen utilization is free of toxic gases formation as well as carbon dioxide (CO 2 ) emission. Hydrogen production can be implemented using a wide variety of resources including fossil fuels, nuclear energy and renewable and sustainable energy (RSE). Amongst various RSE resources, biomass has great capacity to be employed for renewable hydrogen production. Hydrogen pro- duction from palm solid residue (PSR) via thermochemical process is a perfect candidate for waste-to-well strategy in palm oil mills in Malaysia. In this paper, various characteristics of hydrogen production from thermochemical process of PSR includes pyrolysis and gasiﬁcation are reviewed. The annual oil palm fruits production in Malaysia is approximately 100 million tonnes which the solid waste of the fruits is capable to generate around 1.05  10 10 kgH 2 (1.26 EJ) via supercritical water gasiﬁcation (SCWG) process. The ratio of energy output to energy input of SCWG process of PSR is about 6.56 which demonstrates the priority of SCWG to transform the energy of PSR into a high energy end product. The high moisture of PSR which is the most important barrier for its direct combustion, emerges as an advantage in thermo- chemical reactions and highly moisturized PSR (even more than 50%) is utilized directly in SCWG without application of any high cost drying process. Implementation of appropriate strategies could lead Malaysia to supply about 40% of its annual energy demand by hydrogen yield from SCWG of PSR. Ó 2015 Elsevier Ltd. All rights reserved. Contents 1. Introduction ......................................................................................................... 416 2. Roadmap of renewable hydrogen production in Malaysia .................................................................... 417 3. An overview of biomass................................................................................................ 417 3.1. Oil palm biomass................................................................................................ 418 3.2. Chemical structure of palm solid residue ............................................................................ 420 4. Hydrogen production from biomass ...................................................................................... 420 4.1. Hydrogen production from pyrolysis of palm solid residue .............................................................. 421 4.2. Gasification of palm solid residue .................................................................................. 423 4.2.1. Supercritical water gasification ............................................................................. 425 4.2.2. Efficiency of SCWG process ................................................................................ 425 5. Conclusion .......................................................................................................... 427 References .......................................................................................................... 427 http://dx.doi.org/10.1016/j.enconman.2015.02.012 0196-8904/Ó 2015 Elsevier Ltd. All rights reserved. Abbreviations: CCS, CO 2 capturing system; CPO, crude palm oil; CS, coconut shell (CS); CFBG, compartmental ﬂuidized bed gasiﬁer; EFB, empty fruit bunches; ER, equivalence ratio; FFB, fresh fruit bunches; GHG, greenhouse gas; GW, global warming; HFC, hydrogen fuel cell; ICA, integrated catalytic adsorption; LHV, lower heating value; MEWC, Ministry of Energy, Water, and Communication; NG, natural gas; NSC, National Steering Committee; MSW, municipal solid waste; OTCE, ocean thermal energy conversion; PKS, palm kernel shell; PTM, Malaysian Energy Centre; PSR, palm solid residue; RSE, renewable and sustainable energy; SCWG, supercritical water gasiﬁcation; SMR, steam methane reforming; WGSR, Water–gas shift reaction. ⇑ Corresponding author. Tel.: +60 1112600959. E-mail address: Seyed.ehsan.hosseini@gmail.com (S.E. Hosseini). Energy Conversion and Management 94 (2015) 415–429 Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman