4-E (environmental, economic, energetic and exergetic) analysis of slow pyrolysis of lignocellulosic waste

The bio-waste slow pyrolysis process is assessed by four indicators to determine its energetic, exergetic, economic and environmental performance. The influence of the pyrolysis temperature (300-800 degrees C) on these parameters, but also on the biochar, bio-oil and gas production, is analysed. The biochar yield decreased 10.5% and the gas yield increased 17.2% between 300 and 800 degrees C. The bio-oil yield increased about 2.1% between 300 and 500 degrees C and decreased about 8% between 500 and 800 degrees C. Within the temperature range 300-800 degrees C, the H-2, CO and CH4 molar fractions increased 51.4, 6.6 and 0.3%, respectively. CO2 content decreased about 58.3%. The exergy efficiency varied between 81.16 and 85.33% in this temperature range. The exergy-based economic factor revealed that 15.38-19.16% of the total cost was associated with the exergy destruc-tion. The environmental impact was lower at higher temperatures. The recommended temperature range is 300-400 degrees C to produce biochar, and temperatures of over 700 degrees C to produce gas. When the interest focus is on the bio-oil, it is recommended to work close to 500 degrees C. (c) 2020 Elsevier Ltd. All rights reserved.