Effect of process parameters on production of biochar from biomass waste through pyrolysis: A review Manoj Tripathi a , J.N. Sahu b,n , P. Ganesan a a Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia b Petroleum and Chemical Engineering Programme Area, Faculty of Engineering, Institut Teknologi Brunei, Tungku Gadong, P.O. Box 2909, Brunei Darussalam article info Article history: Received 10 December 2014 Received in revised form 12 August 2015 Accepted 26 October 2015 Keywords: Biomass Thermochemical conversion Pyrolysis Process parameter Biochar abstract Biomass is considered to have potential to be used as an alternative energy source. High carbon content present in biomass converts it into high energy biochar on thermochemical treatment. Among few well established thermochemical technologies for the treatment of biomass and biogenic waste to produce high energy char along with oil and gaseous yield, pyrolysis is the most studied and discussed technique in the recent past. A comparison between the existing techniques is established in the present work. Production of char from the biomass and biogenic wastes is reviewed and it was found that yield of the biochar depends upon the biomass composition like moisture content and presence of cellulose or lignin. Pyrolysis product distribution and their quality strongly depend upon the process parameters. Different biomasses which can be used as raw material in pyrolysis are also reviewed and categorized depending upon their source. Pyrolysis process parameters such as temperature, heating rate, residence time etc. also influence the biochar yield. This study discusses the effect of these process parameters on the production of biochar through pyrolysis of biomass. & 2015 Elsevier Ltd. All rights reserved. Contents 1. Introduction ........................................................................................................ 468 2. Biomass ........................................................................................................... 468 2.1. Source of biomass ............................................................................................. 469 2.2. Type of biofuel obtained from biomass ............................................................................ 469 2.2.1. 1st Generation biofuel ................................................................................... 469 2.2.2. 2nd Generation biofuel .................................................................................. 469 2.2.3. 3rd Generation biofuel .................................................................................. 469 2.2.4. 4th Generation biofuel................................................................................... 469 2.3. Chemical composition of biomass................................................................................. 470 3. Biochar production techniques ......................................................................................... 470 3.1. Combustion .................................................................................................. 471 3.2. Gasification .................................................................................................. 471 3.3. Pyrolysis ..................................................................................................... 471 3.3.1. Pyrolysis principle ...................................................................................... 471 3.3.2. Types of pyrolysis ...................................................................................... 472 3.3.3. Pyrolysis products ...................................................................................... 473 3.3.4. Advantages of pyrolysis .................................................................................. 473 3.4. Comparison of biochar production techniques....................................................................... 473 4. Effect of biomass constituent .......................................................................................... 474 5. Effect of operating parameters ......................................................................................... 475 5.1. Effect of residence time ......................................................................................... 475 5.2. Effect of particle size ........................................................................................... 475 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.2015.10.122 1364-0321/& 2015 Elsevier Ltd. All rights reserved. n Corresponding author. Tel.: þ603 7967 5295(O); fax: þ603 7967 5319. E-mail addresses: jn.sahu@itb.edu.bn, jay_sahu@yahoo.co.in (J.N. Sahu), poo_ganesan@um.edu.my (P. Ganesan). Renewable and Sustainable Energy Reviews 55 (2016) 467–481