There has been an enormous amount of research in recent years in the area of thermo-chemical conversion of biomass into bio-fuels (bio-oil, bio-char and bio-gas) through pyrolysis technology due to its several socio-economic advantages as well as the fact it is an efficient conversion method compared to other thermo-chemical conversion technologies. However, this technology is not yet fully developed with respect to its commercial applications. In this study, more than two hundred publications are reviewed, discussed and summarized, with the emphasis being placed on the current status of pyrolysis technology and its potential for commercial applications for bio-fuel production. Aspects of pyrolysis technology such as pyrolysis principles, biomass sources and characteristics, types of pyrolysis, pyrolysis reactor design, pyrolysis products and their characteristics and economics of bio-fuel production are presented. It is found from this study that conversion of biomass to bio-fuel has to overcome challenges such as understanding the trade-off between the size of the pyrolysis plant and feedstock, improvement of the reliability of pyrolysis reactors and processes to become viable for commercial applications. Further study is required to achieve a better understanding of the economics of biomass pyrolysis for bio-fuel production, as well as resolving issues related to the capabilities of this technology in practical application.

https://cyberleninka.org/article/n/1011788.pdf

Biofuels production through biomass pyrolysis - a technological review.

A review on the preparation of the activated carbon from agricultural waste material is presented. The physical properties such as proximate and ultimate analysis of agricultural waste material were reviewed. The chemical compositions such as cellulose, hemicelluloses and lignin contents were also discussed. The effects of various parameters on the preparation such as carbonization and activation temperature, time, types of activating agents and impregnation ratio were reviewed. Various physical and chemical processes for the activation of the agricultural residues and their effects on the textural properties such as surface area and pore volume were discussed. The low cost, renewable and relatively less expensive of the agricultural waste were found to be efficiently being converted into wealth. The uses of activated carbon derived from agricultural residues in many fields were evidently proven in the review. The reaction kinetic modeling on the pyrolysis and activation of agricultural wastes were also reviewed.

Agricultural bio-waste materials as potential sustainable precursors used for activated carbon production: A review

Production and utilization of biochar: A review

Biochar application to soils is being considered as a means to sequester carbon (C) while concurrently improving soil functions. The main focus of this report is providing a critical scientific review of the current state of knowledge regarding the effects of biochar application to soils on soil properties and functions. Wider issues, including atmospheric emissions and occupational health and safety associated to biochar production and handling, are put into context. The aim of this review is to provide a sound scientific basis for policy development, to identify gaps in current knowledge, and to recommend further research relating to biochar application to soils. See Table 1 for an overview of the key findings from this report. Biochar research is in its relative infancy and as such substantially more data are required before robust predictions can be made regarding the effects of biochar application to soils, across a range of soil, climatic and land management factors. Definition In this report, biochar is defined as: “charcoal (biomass that has been pyrolysed in a zero or low oxygen environment) for which, owing to its inherent properties, scientific consensus exists that application to soil at a specific site is expected to sustainably sequester carbon and concurrently improve soil functions (under current and future management), while avoiding shortand long-term detrimental effects to the wider environment as well as human and animal health." Biochar as a material is defined as: "charcoal for application to soils". It should be noted that the term 'biochar' is generally associated with other co-produced end products of pyrolysis such as 'syngas'. However, these are not usually applied to soil and as such are only discussed in brief in the report. Biochar properties Biochar is an organic material produced via the pyrolysis of C-based feedstocks (biomass) and is best described as a ‘soil conditioner’. Despite many different materials having been proposed as biomass feedstock for biochar (including wood, crop residues and manures), the suitability of each feedstock for such an application is dependent on a number of chemical, physical, environmental, as well as economic and logistical factors. Evidence suggests that components of the carbon in biochar are highly recalcitrant in soils, with reported residence times for wood biochar being in the range of 100s to 1,000s of years, i.e. approximately 101,000 times longer than residence times of most soil organic matter. Therefore, biochar addition to soil can provide a potential sink for C. It is important to note, however, that there is a paucity of data concerning biochar produced from feedstocks other than wood, but the information that is available is discussed in the report. Owing to the current interest in climate change mitigation, and the irreversibility of biochar application to soil, an effective evaluation of biochar stability in the environment and its effects on soil processes and functioning is paramount. The current state of knowledge concerning these factors is discussed throughout this report.

Biochar Application to Soils - A Critical Scientific Review of Effects on Soil Properties, Processes and Functions

Hydrothermal carbonization (HTC) is a thermochemical conversion technique which is attractive due to its ability to transform wet biomass into energy and chemicals without predrying. The solid product, known as hydrochar, has received attention because of its ability to prepare precursors of activated carbon in wastewater pollution remediation, soil remediation applications, solid fuels, and other carbonaceous materials. Besides the generally lignocellulose biomass used as sustainable feedstock, HTC has been applied to a wide range of derived waste, including sewage sludge, algae, and municipal solid waste to solve practical problems and generate desirable carbonaceous products. This review presented the critical hydrothermal parameters of HTC, including temperature, residence time, heating rate, reactant concentration, and aqueous quality. The chemical reaction mechanisms involved in the formation of hydrochar derived from single components and representative feedstock, lignocellulose, and sludge termed as N-free and N-rich biomass, were elucidated and summarized to better understand the hydrochar formation process. Specifically, hydrochar physicochemical characteristics such as surface chemistry and structure were investigated. Current knowledge gaps, and new perspectives with corresponding recommendations were provided to further exploit the great potential of the HTC technique and more practical applications for hydrochar in the future.

A review of the hydrothermal carbonization of biomass waste for hydrochar formation: process conditions, fundamentals, and physicochemical properties.

Pyrolysis of various biomass residues and char utilization for the production of activated carbons.

Study of biodiesel production from animal fats with high free fatty acid content

In this work, the quality of biodiesel produced by basic transesterification from several vegetable oils (soybean, rapeseed, sunflower, high oleic sunflower, Cynara Cardunculus L., Brassica Carinata and Jatropha Curca) cultivated in Extremadura has been studied in detail. The influence of raw material composition on properties such as density, viscosity, cetane number, higher heating value, iodine and saponification values and cold filter plugging point has been verified. Other biodiesel properties such as acid value, water content and flash and combustion points were more dependent on characteristics of production process. Biodiesel produced by rapeseed, sunflower and high oleic sunflower oils transesterification have been biofuels with better properties according to Norm EN 14214. Finally, it has been tested that it is possible to use oils mixtures in biodiesel production in order to improve the biodiesel quality. In addition, with the same process conditions and knowing properties of biodiesel from pure oils; for biodiesel from oils mixtures, its methyl esters content, and therefore properties dependent this content can be predicted from a simple mathematical equation proposed in this work. (C) 2014 Elsevier Ltd. All rights reserved.

G. Martínez

Papers

Pyrolysis of various biomass residues and char utilization for the production of activated carbons.

Study of biodiesel production from animal fats with high free fatty acid content

Fuel properties of biodiesel from vegetable oils and oil mixtures. Influence of methyl esters distribution

Soybean oil transesterification by the use of a microwave flow system

Catalytic pyrolysis of exhausted olive oil waste