Bioenergy Potential of Biomass Produced on Marginal Lands

Abstract

Biomass is believed as the only foreseeable feedstock for sustainable production of clean energy. However, it cannot be produced using agricultural lands to avoid the competition with the land for food crops. Hence, the plants/grasses adapted to poor soils (marginal lands) can be exploited for energy production without causing any negative impact. Pakistan is a 6th most populous country in the world, where the total population is even greater than Russia. So, the country has huge energy demands and is passing through the worst energy crisis in its history. Moreover, 64% of its energy requirements are being met through combustion of fossil fuels which is alarming in terms of environmental stability. Hence, it is essentially required to explore alternative, clean and sustainable energy sources. Biomass produced on marginal lands offers a promising alternative. Pakistan has 9 million hectares of salt-affected soils which is unfit for agricultural activity. The present study was focused to evaluate the bioenergy potential of the grasses adapted to this salt-affected area. The thermodynamics, thermal degradation and kinetics of selected grasses namely Para grass (Urochloa mutica), Elephant grass (Permisetum purpureum), Babui grass (Eulaliopsis binate), Mott grass (Pennesetum benthiumo), Egyptian grass (Dactyloctenium aegyptium), Carrot grass (Parthenium hysterophorus), Camel grass (Cymbopogon schoenanthus) and Cattail (Typha latifolia) produced on marginal lands in Pakistan without any fertilizers, pesticide and agriculture practices. All above biomass samples were thermally degraded in Nitrogen environment under three different heating rates (10, 30 and 50) ºC min-1. The thermodynamic and thermokinetic parameters were investigated using iso-conversion methods including KAS (Kissenger-Akahira-Sunose) and FWO (Flynn-WallOzawa). Whereas peak zones were also examined throughout the DTG curves under three different heating rates. Degradation regions were also determined on the basis of degradation of lignin, cellulose and hemicellulose components. High heating values were determined to range from 15-18 MJ kg-1. Similarly, activation energy, Gibbs free energy and enthalpy values of all biomass samples were determined which showed to be ranging from 166-267 kJ mol-1, 166-177 kJ mol-1and 161-262 kJ mol-1 respectively. All biomass samples had first order preexponential factors. Our data showed all biomass samples had remarkable potential to adopt as a low-cost biomass for bioenergy production through pyrolysis.