Journal of Energy Bioscience 2024, Vol.15, No.2, 118-131 http://bioscipublisher.com/index.php/jeb 125 6.4 Use of computational models and simulations for process optimization Computational models and simulations have become invaluable tools for optimizing the anaerobic digestion process. These models can simulate various scenarios and predict the outcomes of different operational strategies, allowing for the identification of optimal conditions for biogas production. By incorporating factors such as feedstock composition, loading rates, and environmental conditions, these models provide insights into the complex interactions within the digester. The use of computational models has led to significant improvements in the design and operation of AD systems, resulting in higher biomethane yields and more efficient waste-to-energy conversion (Muscolo et al., 2017; Salman et al., 2017; Nguyen et al., 2020; Neri et al., 2023). In conclusion, the advancements in anaerobic digestion technology, including the integration with other renewable energy sources, development of hybrid systems, application of real-time monitoring and control systems, and the use of computational models, have significantly enhanced the efficiency and sustainability of converting agricultural waste into biomethane. These innovations not only improve biogas production but also contribute to the broader goals of renewable energy generation and waste management. 7 Environmental and Economic Benefits 7.1 Reduction of greenhouse gas emissions Anaerobic digestion (AD) of agricultural waste significantly reduces greenhouse gas (GHG) emissions by capturing methane that would otherwise be released into the atmosphere from decomposing organic matter. The process of converting organic waste into biogas, primarily composed of methane (CH4) and carbon dioxide (CO2), helps mitigate the release of these potent GHGs. Studies have shown that AD can effectively reduce GHG emissions by diverting organic waste from landfills and utilizing it for energy production (Muscolo et al., 2017; Zhang et al., 2019; Dutta et al., 2021). Additionally, the integration of AD with other technologies, such as pyrolysis, can further enhance the reduction of carbon emissions by converting digestate into biochar, which sequesters carbon (Salman et al., 2017; Dutta et al., 2021). 7.2 Resource recovery and nutrient recycling AD not only produces biogas but also generates nutrient-rich digestate, which can be used as a biofertilizer. This digestate contains essential nutrients such as nitrogen, phosphorus, and potassium, which are beneficial for soil health and crop production. The application of digestate to agricultural lands can improve soil organic matter, enhance microbial activity, and promote sustainable farming practices (Sheets et al., 2015; Stoknes et al., 2016; Muscolo et al., 2017). Moreover, emerging technologies are being developed to further treat and reuse AD effluent, ensuring that both the liquid and solid fractions are effectively utilized, thereby closing the resource loop and supporting a circular economy (Sheets et al., 2015; Dutta et al., 2021). 7.3 Energy production and potential for grid integration The biogas produced through AD can be used for various energy applications, including electricity generation, heating, and as a vehicular fuel. Upgrading biogas to biomethane allows for its injection into the natural gas grid, providing a renewable energy source that can be distributed and used widely (Molino et al., 2013; Verbeeck et al., 2018; Kassem et al., 2020). This integration with the gas grid not only enhances energy security but also supports the decarbonization of the energy sector. For instance, a study demonstrated the feasibility of producing renewable natural gas (RNG) from dairy waste and injecting it into the gas pipeline, contributing to grid decarbonization and reducing reliance on fossil fuels (Kassem et al., 2020). 7.4 Economic feasibility and cost-benefit analysis The economic viability of AD technology is influenced by several factors, including the cost of feedstock, operational expenses, and the market value of biogas and digestate. Government incentives and carbon credit mechanisms play a crucial role in making AD projects financially attractive. For example, the Low Carbon Fuel Standard (LCFS) and Renewable Fuel Standard (RFS) can significantly enhance the net present value (NPV) of AD projects, making them economically feasible (Kassem et al., 2020). Additionally, integrating AD with other processes, such as pyrolysis, can increase the overall efficiency and revenue of the system, as demonstrated by a
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