Energy Recovery from Biowaste and Biomass via Gasification: A Modelling Approach

Area of Science:

• * Circular bioeconomy and renewable energy production.
• * Waste-to-energy technologies and sustainable resource management.

Background:

• * Transitioning to a circular bioeconomy necessitates efficient conversion of biogenic wastes and biomass into renewable fuels.
• * High-moisture biowastes like wastewater sludge (WWS) and food waste (FW) present unique challenges and opportunities for gasification compared to lignocellulosic biomass (e.g., softwood, SW).

Purpose of the Study:

• * To evaluate the gasification potential of WWS and FW against SW using an equilibrium model.
• * To assess the impact of air and steam gasification parameters on gas composition and energy efficiency.
• * To determine the feasibility of utilizing wet biowastes as sustainable feedstocks for syngas production.

Main Methods:

• * Development of an Aspen Plus equilibrium model incorporating a drying stage.
• * Simulation of air and steam gasification processes for WWS, FW, and SW.
• * Examination of temperature (400-1200 °C), equivalence ratio (ER = 0.1-1), and steam-to-biomass ratio (S/B = 0.1-1) effects.

Main Results:

• * Maximum energy efficiency (EE) was observed at intermediate temperatures, with EE order: SW > FW > WWS.
• * Steam gasification significantly increased H₂ content (up to 54%), while air gasification yielded 70-80% EE at low ER.
• * Despite high drying energy demands, WWS and FW demonstrated robust energy efficiencies (60-80%).

Conclusions:

• * Wet biowastes (WWS, FW) can achieve gasification performance comparable to lignocellulosic biomass (SW).
• * Both air and steam gasification are viable for waste-to-syngas conversion, with steam favoring H₂ production.
• * These findings support the integration of bioenergy into waste management systems and the advancement of the circular bioeconomy.