Production of Solid Fuel by Torrefaction Using Coconut Leaves As Renewable Biomass

Abstract

ABSTRACT. The reserves of non-renewable energy sources such as coal, crude oil and natural gas are not limitless, they gradually get exhausted and their price continually increases. In the last four decades, researchers have been focusing on alternate fuel resources to meet the ever increasing energy demand and to avoid dependence on crude oil (Karunanithy et al. 2012). Amongst different sources of renewable energy, biomass residues hold special promise due to their inherent capability to store solar energy and amenability to subsequent conversion to convenient solid, liquid and gaseous fuels. At present, among the coconut farm wastes such as husks, shell, coir dust and coconut leaves, the latter is considered the most grossly under-utilized by in situ burning in the coconut farm as means of disposal. In order to utilize dried coconut leaves and to improve its biomass properties, this research attempts to produce solid fuel by torrefaction using dried coconut leaves for use as alternative source of energy that can be utilized in the indirect drying of coconut meat in the farm-level to produce copra. Torrefaction is a thermal method for the conversion of biomass operating in the low temperature range of 200 o C-300 o C under atmospheric conditions in absence of oxygen. Dried coconut leaves were torrefied at different feedstock conditions. The key torrefaction products were collected and analyzed. Physical and combustion characteristics of both torrefied and untorrefied biomass were investigated. Torrefaction of dried coconut leaves significantly improved the heating value compared to that of the untreated biomass. Proximate compositions of the torrefied biomass also improved and were comparable to coal. The distribution of the products of torrefaction depends highly on the process conditions such as torrefaction temperature and residence time. Physical and combustion characteristics of torrefied biomass were superior making it more suitable for fuel applications.

Development of Torrefaction Technology for Solid Fuel Using Renewable Biomass

“…Thermal conversion processes can be categorized into combustion, gasification, pyrolysis and the emerging torrefaction technology according to the operating conditions. The products of the thermochemical processes are divided into a volatile fraction consisting of gases, vapors and tar components and a carbon rich solid residue [4].…”

“…It is a thermal pre-treatment technology carried out at atmospheric pressure in the absence of oxygen. Torrefaction of biomass can be described as a mild form of pyrolysis that occurs at temperatures between 200 and 300°C [4]. During torrefaction, the more easily combustible components of biomass (i.e.…”

“…The thermal behaviors of dried coconut leaves [4,5], cogongrass [5] and rice husks [5] (about 5.769 mg milled using a Thomas Willey mill) were investigated at the Polymer Materials Laboratory at the Institute of Chemistry, College of Science, University of the Philippines, Dilijan, Quezon City using a TGA Q50 (TA Instrument). The heating program consisted on a 5 min hold at 30°C, ramp up to 800°C at a heating rate of 10°C/min, and then the weight difference was recorded as a function of temperature profile.…”

“…The heating program consisted on a 5 min hold at 30°C, ramp up to 800°C at a heating rate of 10°C/min, and then the weight difference was recorded as a function of temperature profile. Nitrogen was used as a purging gas at a flow rate of 50 ml/min [4].…”

“…In order to utilize agricultural crop residues and to improve its biomass properties, there is a need to create new knowledge and apply it to be more productive focusing on creativity and innovation. Agricultural crop residues that are abundant in the Philippines such as coconut leaves [4,5], cogongrass [5], and rice husk [5], were utilized to produce solid fuel by torrefaction for use as alternative source of energy. The design of the torrefaction process based on the biomass characteristics was researched and developed.…”