Impact of anaerobically digested pretreated crop residue on performance and economics of solar photovoltaic-biomass microgrid system

Abstract

Farmers frequently burn crop residue in the fields, significantly polluting the environment and raising carbon emissions. However, crop residue/biomass can be utilized for biogas production through anaerobic digestion, offering a sustainable alternative to burning and providing valuable biogas for other purposes. For optimal biogas production, pretreatment of crop residue before subjecting it to anaerobic digestion is essential to breaking down its lignocellulose matrix, which is otherwise resistant to degradation. This study investigates the effect of alkaline (2% NaOH) and wastewater pretreatments on crop residue (i.e., bagasse and rice straw) in relation to biogas production efficiency, specifically focusing on the biogas output to feedstock input ratio. Laboratory-scale experiments were conducted using six one-liter digesters in a batch mode process to measure the biogas yield relative to the feedstock input. The experimental data were then incorporated into simulations to assess the potential impact on electricity production and the economics of the solar photovoltaic/biomass-based microgrid system. The results indicated that bagasse pretreated with wastewater yielded the most optimal microgrid system, generating 148,343 kWh/yr of energy through biogas-based generator, with a net present cost of $39,4431 and cost of energy of 0.131$/kWh. The study reveals that pretreated crop residue has the potential to enhance biogas production and improve the economic feasibility of microgrid systems in an eco-friendly manner.