Thermal Properties of Biochars Derived from Waste Biomass Generated by Agricultural and Forestry Sectors

Xing Yang,Lei Che,Shujuan Liu,Kuichuan Sheng,Lizhi He,Kouping Lu,Jia Guo,Hailong Wang,Ying Shen,Yong Ok,Peter Strong,Song Xu,Xin Chen,Guodong Yuan

doi:10.3390/en10040469

Abstract

Waste residues produced by agricultural and forestry industries can generate energy and are regarded as a promising source of sustainable fuels. Pyrolysis, where waste biomass is heated under low-oxygen conditions, has recently attracted attention as a means to add value to these residues. The material is carbonized and yields a solid product known as biochar. In this study, eight types of biomass were evaluated for their suitability as raw material to produce biochar. Material was pyrolyzed at either 350 °C or 500 °C and changes in ash content, volatile solids, fixed carbon, higher heating value (HHV) and yield were assessed. For pyrolysis at 350 °C, significant correlations (p < 0.01) between the biochars’ ash and fixed carbon content and their HHVs were observed. Masson pine wood and Chinese fir wood biochars pyrolyzed at 350 °C and the bamboo sawdust biochar pyrolyzed at 500 °C were suitable for direct use in fuel applications, as reflected by their higher HHVs, higher energy density, greater fixed carbon and lower ash contents. Rice straw was a poor substrate as the resultant biochar contained less than 60% fixed carbon and a relatively low HHV. Of the suitable residues, carbonization via pyrolysis is a promising technology to add value to pecan shells and Miscanthus.

Highlights

By 2020, the use of petroleum and other liquid fuels is estimated to reach nearly 100 million bpd globally, and this is anticipated to increase a further 10% by 2035 [1]
The results of this study demonstrate that the thermal properties and yields of biochars differ vastly for different biomass feedstocks
The effects on volatile solid and fixed carbon content were more dependent on pyrolysis temperature, while the ash contents of biochar were dependent on feedstock composition more than pyrolysis temperature

Summary

Introduction

By 2020, the use of petroleum and other liquid fuels is estimated to reach nearly 100 million bpd globally, and this is anticipated to increase a further 10% by 2035 [1]. Biomass energy currently provides almost 14% of the world’s primary energy. It is regarded as the renewable fuel with the highest potential for sustainable development in the future, and its adoption can significantly lower fossil fuel use and CO2 emissions [3]. A providing sustainable energy solution is urgently required in developing countries

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