Lorena Torres Albarracin

Psychrophilic anaerobic digestion emerges as an appealing integrated solution for the management of agricultural waste, particularly for farmers in regions where the average temperature does not exceed 26 °C, as seen in coffee cultivation. Therefore, this study seeks to assess the biomethane potential of thermochemical-treated coffee husk through psychrophilic anaerobic digestion (C3-20 °C-w/pretreatment). To examine its viability, outcomes were compared with reactors operating at both mesophilic (C1-35 °C) and psychrophilic (C2-20 °C) conditions, albeit without the use of pretreated coffee husk. The C3-20 °C-w/pretreatment test demonstrated a 36.89% increase (150.47 NmL CH₄/g VS; 161.04 NmL CH₄/g COD), while the C1-35 °C test exhibited a 24.03% increase (124.99 NmL CH₄/g VS; 133.77 NmL CH₄/g COD), both in comparison to the C2-20 °C test (94.96 NmL CH₄/g VS; 101.63 NmL CH₄/g COD). Notably, the C3-20 °C-w/pretreatment trial yielded superior outcomes, accompanied by an associated energy output of 3199.25 GWh/year, sufficient to meet the annual energy demands of 494 residences. This marks an increase of 83 and 182 million residences compared to the mesophilic and psychrophilic AD of CH without pretreatment, respectively.

Coffee processing generates a large amount of organic waste, which has the potential for energy use through biogas production. Although Brazil dominates world coffee production, treating its residue with biogas technology is not a practice, especially due to this product’s seasonality, which hampers continuous digester operation. The implementation of biogas production from coffee residues in a concept of industrial symbiosis could overcome this. This work evaluates the biogas energy potential from the main liquid residues of coffee processing (i.e., mucilage and wash water) and their integration with glycerin and cattle manure. Around 2773 m³ biogas day⁻¹ would be produced (75% CH₄), used as biomethane (734 thousand m³ year⁻¹), or thermal energy (23,000,000 MJ year⁻¹), or electricity (2718 MWh year⁻¹), which could supply, respectively, all the liquefied petroleum gas (LPG) and diesel demands of the farm, all the thermal energy demands of the grain drying process, as well as electricity for 30 residences. Considering the short coffee season, the results have a broader context for the application of biogas production on coffee processing farms, envisaging that the Agroindustrial Eco-Park concept has the potential to integrate various agroindustrial sectors for energy production, residue exchange, and water recirculation.

Psychrophilic anaerobic digestion emerges as an appealing integrated solution for the management of agricultural waste, particularly for farmers in regions where the average temperature does not exceed 26°C, as seen in coffee cultivation. Therefore, this study seeks to assess the biomethane potential of thermochemical treated coffee husk through psychrophilic anaerobic digestion (C3-20°C-w/pretreatment). To examine its viability, outcomes were compared with reactors operating at both mesophilic (C1-35°C) and psychrophilic (C2-20°C) conditions, albeit without the use of pretreated coffee husk. The C3-20°C-w/pretreatment test demonstrated a 36.89% increase (150.47 mL CH4/g VS; 161.04 mL CH4/g COD), while the C1-35°C test exhibited a 24.03% increase (124.99 mL CH4/g VS; 133.77 mL CH4/g COD), both in comparison to the C2-20°C test (94.96 mL CH4/g VS; 101.63 mL CH4/g COD). Notably, the C3-20°C-w/pretreatment trial yielded superior outcomes, accompanied by an associated energy output of 4262.2 KWh/year, sufficient to meet the annual energy demands of 588 residences. This marks an increase of 100 and 217 residences compared to mesophilic and psychrophilic AD of CH without pretreatment, respectively.

Recently, new solutions have arisen to promote bioenergy expansion, some of which meet the requirements of reliability, sustainability, and governance. In Brazil, the Sao Paulo state (SPS) is characterized by strong agro‐industrial and livestock activities, which generates increasing residues in the last years with the potential to produce bioenergy and offer environmental and economic benefits. The Brazilian National Biofuel Policy (Renovabio) has been enhanced to seek sustainable development, encouraging new agribusiness research. Studies have shown that the sugarcane sector, a conventional ethanol and bioelectricity producer, has the greatest potential to produce biogas/biomethane, which can be maximized with the introduction of co‐substrates regionally generated from corn, soy, orange, coffee, poultry, and swine. This overview, based on the main SPS agro‐industrial and livestock residues, shows innovative alternatives for integrating anaerobic co‐digestion (co‐AD) processes through a regional strategy, by providing long‐term revenues and greenhouse gas mitigation, which would also spread the discussion for National and International prospects. This study discusses logistical, political, and financial aspects, revealing a promising business model supported by public policies. However, its feasibility requires a real economic assessment with the inclusion of decarbonization credits, and political subsidies for biomethane as a biofuel under the Renovabio, which will facilitate its insertion into the agro‐industry in the coming years.This article is categorized under: Policy and Economics > Energy Transitions Sustainable Energy > Bioenergy Climate and Environment > Circular Economy Policy and Economics > Regional and International Strategies

Brazil's agriculture and livestock annually generates enormous amounts of biomass, which varies in its biochemical composition. Many studies have pointed out the benefits of using this biomass as a substrate for biogas production through anaerobic digestion (AD), mostly via the co‐digestion (co‐AD) pathway. The agriculture and livestock of southeastern Brazil – sugarcane, orange, corn, soybean, coffee, cattle, swine, and poultry – have together demonstrated their potential for producing biomass that can be used for maximizing methane production. Filter cake, vinasse, straws, bagasse, mucilage, pulp, washing water, thin stillage, and manures also have specific organic matter and nutrient content that can be evaluated from an economic perspective as co‐products of biorefineries. Some are costless but others have acquisition costs in the agricultural market. Comparing the recent biochemical compositions cited in scientific literature (technical parameter) and to know the costs (valuation parameter) is crucial for farmers and investors make decisions in large‐scale. This study conducted a bibliographical survey of biomass generated in Brazilian agroindustry as a co‐substrate for energy production. The analysis summarized two tables: 1‐ a compilation of biochemical composition of the main co‐substrates, and 2‐ the acquisition or opportunity costs, discussing innovative aspects in the context of biogas production. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.