Co-Pyrolysis of Date Palm Waste and Salicornia Bigelovii: Insights for Bioenergy Development in Arid and Semi-Arid Regions

Abstract

Bioenergy is predicted to significantly contribute to the global energy needs of both developed and developing economies. Co-pyrolysis of halophytes offers a solution for a sustainable supply of feedstock in coastal and water-scarce regions. This novel research introduces an experimental investigation of co-pyrolysis of saline-tolerant flora (date palm waste and Salicornia bigelovii) to address sustainable waste management, bioenergy production, and efficient resource utilization in xeric regions. To examine the impact of the thermic condition on the pyrolysis products (bio-oil, biochar, and gas), the experiments have been conducted at three different temperatures (400, 500, and 600 °C). This pioneering study revealed that the co-feed bio-oil is acidic (pH 3.76–4.39) and has a high energy content (HHV 32.29–36.29 MJ/kg) that surpasses most woody biomass. The produced biochar was chemically stable, high in ash (40.09–47.62 wt %), high in fixed carbon (30.12–38.12 wt %), highly alkaline (pH 9.37–10.69), and low in HHV (16.30–17.2 MJ/kg). Increased pyrolysis temperature enhances biochar stability and fixed carbon, thus benefiting long-term carbon sequestration if applied in the soil. However, due to its high alkalinity, the application of this biochar in naturally alkaline sandy soils, such as in coastal deserts, requires careful monitoring. The hydrogen content in the gaseous phase significantly improves with rising temperature, reaching HHV = 24.12 MJ/kg at 600 °C, due to the enhanced ash catalytic effect. Overall, this study constitutes an important contribution to advancing bioenergy, sustainable feedstock, carbon capture, and waste management strategies in drought-prone areas.