A first order methodology for the sizing and siting of utility-scale biogas plants processing Egypt's lignocellulosic biomass.

Anaerobic co-digestion of food waste and agricultural residues: An overview of feedstock properties and the impact of biochar addition

Agricultural waste represents a largely untapped resource that could be utilized for the production of biofuels through various conversion pathways. As the global demand for renewable and sustainable energy grows, biofuels offer solutions to mitigate climate change impacts while improving waste management. This review analyzes using agricultural residues and by-products as feedstocks for biofuel production through biological, thermochemical and chemical conversion processes. The different types of lignocellulosic biomass available from agricultural activities are discussed, along with their compositions. While agricultural waste has advantages like wide availability and low cost, challenges relating to heterogeneous composition, pre-existing contamination and seasonal availability must be addressed. Fermentation, anaerobic digestion, pyrolysis and gasification are examined as established routes for converting agricultural waste into liquid biofuels and biogas. Pretreatment methods, enzyme production pathways and synthesis of fuels like ethanol, butanol and diesel substitutes are outlined. Environmental benefits of biofuels from waste, including greenhouse gas mitigation and recycling of soil nutrients, are evaluated against fossil fuel alternatives. Case studies on operational plants and feasibility studies provide insights into technical and economic viability at scale. Challenges regarding feedstock logistics, conversion efficiency, commercial scale-up and sustainability assessment are identified for future research focus. In conclusion, the review finds that agricultural waste is a promising renewable resource for biofuel production when integrated with appropriate thermochemical, biochemical or anaerobic digestion technologies. While the field is advancing, further improvements in areas such as feedstock supply, pretreatment technologies, and demonstration of sustainability will be critical to realize the full potential of this emerging bioeconomy sector. The review recommends steps to accelerate commercialization and policy frameworks to incentivize waste-to-energy solutions.

LCA analysis of food waste co-digestion

Several years have passed since the linear economy model proved unsustainable, leading to the transition toward the circular economy (CE) model. Significant amounts of agricultural residues and waste from livestock farming units remain unutilized in fields. The anaerobic digestion (AD) method addresses this issue by generating energy in the form of thermal (TE) and electrical energy (EE). This article examines greenhouse heating using thermal energy from a biogas plant. For this purpose, a thermal load model is developed and applied in two regions, northern (Florina) and central Greece (Trikala), to assess the greenhouse’s energy requirements in areas with differing characteristics, especially during the winter months. Additionally, the economic benefits of a biogas plant from selling electricity to the grid are analyzed. Thermal energy constitutes 59.7% of the system’s total energy output. On average, the generated electrical energy amounts to 518 MW h per month, while thermal energy reaches 770 MW h per month. The biogas plant’s daily electricity consumption ranges from 1564 kW h to 2173 kW h, depending on its needs. Ambient temperatures vary between 0 °C and 37 °C, significantly influencing the greenhouse heating system’s efficiency. The biogas plant also demonstrates financial profitability, earning 504,549 € annually from the sale of surplus electricity. Furthermore, the article explores greenhouse crops in the broader Thessaly region, where tomato cultivation seems to be dominant. Greenhouse heating requirements depend on crop type, location, weather conditions, sunlight exposure, and heat loss based on covering materials. Meanwhile, the thermal energy output that can heat a given greenhouse area is directly proportional to the biogas plant’s capacity.

A review about pretreatment of lignocellulosic biomass in anaerobic digestion: Achievement and challenge in Germany and China

In recent decades, biogas production from anaerobic digestion of organic fractions of municipal solid waste and agricultural residues has emerged as a promising strategy for waste management and renewable energy generation. However, due to the complexity and heterogeneity of these feedstocks, an appropriate pre-treatment is required before anaerobic digestion to maximise biodegradability and enhance biogas production. This is especially true for lignocellulosic biomass, where maximum biogas potential is often difficult to reach due to the presence of a lignin barrier, which is not easily biodegradable. Pre-treatment technologies may significantly increase biogas production, up to 360 %, from organic fractions of municipal solid waste and agricultural residues. This paper first provides an overview of the pre-treatment technologies, including mechanical, chemical, biological, thermal, plasma, and combined treatments for a wide variety of feedstocks for biogas production from anaerobic digestion. These studies indicate that the selection of a pre-treatment technology mainly depends on the waste substrate characteristics, the desired end results, and resource availability. Furthermore, most studies emphasise the significance of balancing the benefits and drawbacks of pre-treatment technologies for sustainable waste-to-energy practices. Then, the article evaluates the scalability, technical feasibility, economic viability, industrial applicability and environmental sustainability of appropriate pre-treatment methods. This review will be a valuable resource for researchers, policymakers, and practitioners working in the field of waste-to-energy conversion through anaerobic digestion.

Using Anaerobic Digestion in Methanol Production

Investigating the techno-economic and environmental feasibility of biogas-based power generation potential using food waste in Bangladesh

Australia is one of the major producers and exporter of agricultural products. Annually, Australian agriculture produces approximately 151 Tg CO2 equivalent emissions. The use of fossil fuels in crop cultivation, harvesting and transportation are considered as the primary source of these greenhouse gas (GHG) emissions. Moreover, agronomic management and crop residues left in the field also contribute to these GHG emissions. Alternative waste management practices include the use of crop residues and agro-wastes as feedstocks for bioenergy production. Anaerobic digestion is considered as sustainable environmental technology to convert industrial sugarcane residues to carbon dioxide (CO2) - neutral biogas. The biogas thus produced can be used to produce heat, electricity and upgrade to biomethane for vehicle use. The produced biomethane can replace the diesel consumption associated with GHG emission in cane transport. Sugarcane is one among the most cultivated crop in the world. Australia alone produced nearly 33.5 million tonnes of cane in 2018 (FAO 2018). These large production of sugarcane lead to an increase in crop residues and agro-wastes from the sugarcane industry. In this study, an investigation regarding the anaerobic co-digestion of crop residues and agro-wastes from sugarcane industry viz, sugarcane trash (SCT) or sugarcane bagasse (SCB) with chicken manure (CM) was investigated in a batch experiment at 37 °C. In spite of various researches conducted till date about co-digestion of lignocellulosic waste with manure, no research data was available regarding the effect of feed ratio on co-digestion of SCT/SCB with CM. This research gap was investigated in this study. In addition to this, steam explosion pre-treatment of SCT/SCB was included to investigate how the pre-treatment influence methane yield among different feed ratios of SCT/SCB with CM. At first, SCT and SCB were subjected to steam explosion pre-treatment (steam impregnation at 130 °C for 5 minutes followed by steam explosion). Later, two sets of biochemical methane potential (BMP) tests were conducted at an Inoculum to Substrate Ratio (ISR) of 2. Co-digestion of untreated and steam exploded SCT or SCB with CM was investigated at feed ratios of 75:25, 50:50 and 25:75 on volatile solids (VS) basis. Assays with 100% untreated and steam exploded SCT or SCB were also included. Chemical analysis revealed that the steam explosion improved the VS content in pre-treated biomass compared with untreated biomass. The increase in VS was 1.6% and 5.7% in SCT and SCB, respectively. On the other hand, a slight reduction in total solids (TS) of nearly 4% and 1% were observed in the case of SCT and SCB, respectively. BMP results showed that the steam explosion had a profound effect on the methane production rates and yields, especially for SCB than SCT. Methane (CH4) yields of 201.8 and 199 ml CH4/gVSadded were obtained during the mono-digestion of untreated SCT and SCB, respectively. The corresponding values for 100% steam-exploded SCT and SCB were 207.5 and 225.6 ml/gVSadded, respectively. In comparison to mono-digestion, the co-digestion of SCB or SCT with CM did not improve the methane yields. Nevertheless, pre-treatment improved the methane production rates and yields of pre-treated biomass than untreated biomass. Among the studied feed ratios, best methane yields of 206.5 ml/gVSadded were obtained when steam-exploded SCT was co-digested with CM at 75:25 ratio. However, methane yields decreased with an increase in the amount of CM added. SCB also showed a similar trend. The best methane yield of 199.5 ml/gVSadded was obtained when steam-exploded SCB was co-digested with CM at 75:25 ratio. Among the tested feed ratios, all co-digestion mixtures except for 75:25 and 50:50 ratios of untreated SCT to CM showed synergistic effects. The best synergistic effect of 18.57% was observed when untreated SCB was co-digested with CM at 25:75 ratio. Kinetic modelling results confirmed that the steam explosion pre-treatment improved the methane production rates and yields by increasing the hydrolysis rate constant values. However, a higher hydrolysis rate constant was noticed for SCT than SCB. The highest hydrolysis rate constant of 0.16 d-1 was achieved at feed ratios of 50:50 and 25:75 of pre-treated SCT:CM. Interestingly, more than 75% of methane in pre-treated assays was produced by Day 11. The study thus suggests that the steam explosion can improve the methane production rates, yields and productivity of SCT and SCB. However, the use of CM as co-substrate did not improve the methane yields when compared to the mono-digestion of SCT or SCB, but a positive synergism was evident in most of the co-digestion feed ratios.

Influence of geographical location, crop type and crop residue cover on bacterial and fungal community structures

A significant renewable source nowadays is biomass that covers the 12 % worldwide of the energy needs. The national German market belongs to one of the world leaders regarding the biogas use and production. Around 7800 biogas power plants are located in the Germany in a corresponding capacity of 3.5 GW. The World Bioenergy Association supports that up to 90% of the total bioenergy consumption is going for traditional uses like cooking and heating. The main biomass resources are mainly used for heat and electricity production or for generating secondary energy barriers such as biogas or biofuels. We have a variation of biomass residues that main categories are agricultural, waste, forestry and industrial residues. All the types of the residues have the ability to be used as input in biogas power plants for biogas generation. In the production of biogas the technological process which is used is known as anaerobic digestion. The process is microbiological and during operation the organic material is decomposing in oxygen limited environment. In the biogas generation technologies are given several difference substrates that all have a different environmental performance. The construction of a biogas power plant and its operation results in plenty of safety issues, possible risks and impacts in the human health, animals and the ecosystems. It is highly significant the biogas power plants to provide a safe environment for the employees. The regional state of Brandenburg has been developing regarding the renewable sources of energy. The Ministry of Environment, Health and Consumer Protection has been focused in an innovative policy considering the energy efficiency and energy conservation, however there has been emphasized the production of renewable energy

Feasibility analysis of implementing anaerobic digestion as a potential energy source in Bangladesh

The introduction of biogas plants is a promising way to recycle organic wastes with renewable energy production and reducing greenhouse gas. Application of anaerobic digestate as a fertilizer reduces the consumption of chemical fertilizers. In this study, the survival of pathogenic bacteria and plant growth promoting bacteria (PGPB) in two full-scale biogas plants operated at mesophilic condition were investigated. Feedstock and anaerobic digestate samples were collected from biogas plants and bacteria load in samples were detected using standard dilution plate method. Pathogenic bacteria were reduced to not detected level through mesophilic digestion tank except for Campylobacter. However, it could be reduced by 98.7% through a sterilization tank. Bacillus was detected at 8.00 and 7.81 log10 CFU/g dry matter in anaerobic digestates, and it was also resistant to sterilization tank. Bacillus spp. is considered to be the safe bacteria that hold remarkable abilities for promoting plant growth. The results showed that treatment at biogas plants is effective to reduce pathogenic bacteria in dairy manure, and sterilization could further reduce the sanitary risks of pathogenic bacteria relating to anaerobic digestate application. Anaerobic digestates could also be utilized as bio-fertilizer as the high load of plant growth promoting bacteria.

Modeling the ecosystem service of agricultural residues provision for bioenergy production: A potential application in the Emilia-Romagna region (Italy)

Reduction of viable Mycobacterium avium ssp. paratuberculosis in slurry subjected to anaerobic digestion in biogas plants