A comparative analysis of second-generation biofuels and its potentials for large-scale production in arid and semi-arid regions

This study compares the pyrolysis products from eight different feedstocks of potential availability in arid and semi-arid regions, namely, post-consumption food waste, biosolids (anaerobically digested and undigested sewage sludges), segregated fruits and vegetable waste, animal manure, date palm waste, and halophyte plant (Salicornia bigelovii seed and seedless-plant). Food waste, Salicornia bigelovii seed, and undigested sludge produced the highest bio-oil yield, 38.0 %, 35.3 %, and 32.5 %, respectively. The bio-oils from food waste and Salicornia bigelovii seed were rich in acidic compounds. The former has the highest calorific value (34.7 MJ kg(-1)), while the latter is the lowest due to a significant amount of water (29.9 mass%). The biosolids produced bio-oil rich in alcohols and esters, turning it towards high alkalinity (pH > 9). The biochar from animal manure and biosolids has the lowest calorific value (<10.0 MJ kg(-1)) and the least potential for soil amendment and carbon sequestration due to poor stability, low fixed carbon, and significantly high ash content in the feed (>39 mass%). The gas from digested biosolid has the highest calorific value (>38.9 MJ kg(-1)), benefiting from the presence of high H-2 content (21.2 mass%). Analysis of the potential implementation of the eight feedstocks for pyrolysis in an arid region indicates that food waste is the most promising due to its superior bio-oil quality, higher conversion efficiency, abundant availability, and the possibility of low-cost drying.

Automated summary

This study compared the pyrolysis products of eight different feedstocks in arid regions, including food waste, biosolids, segregated fruits and vegetable waste, animal manure, date palm waste, and halophyte plant. Food waste, Salicornia bigelovii seed, and undigested sludge had the highest bio-oil yield. Bio-oils from food waste and Salicornia bigelovii seed were rich in acidic compounds. Animal manure and biosolids had the lowest calorific value for biochar production. Digested biosolid had high calorific value in gas production. Food waste was identified as the most promising feedstock due to its superior bio-oil quality and abundant availability.