Biogas Production from Organic Waste in the Forestry and Agricultural Context: Challenges and Solutions for a Sustainable Future

Abstract

Biogas produced from agricultural and forestry waste is emerging as a strategic and multifunctional solution to address climate change, inefficient waste management, and the need for renewable energy by transforming large volumes of biomass. Global estimates indicate that approximately 1.3 billion tons of waste is produced each year for these sectors; this waste is processed through anaerobic digestion, allowing it to be transformed into energy and biofertilizers. This reduces greenhouse gas emissions by up to 90%, promotes rural development, improves biodiversity, and prevents environmental risks, such as forest fires. However, despite its high global technical potential, which is estimated at 8000 TWh per year, its use remains limited as a result of its high initial costs, low efficiency in relation to lignocellulosic waste, and weak regulatory frameworks, especially in countries like Mexico, which use less than 5% of their available biomass. In response, emerging technologies, such as co-digestion with microalgae, integrated biorefineries, and artificial intelligence tools, are opening up new avenues for overcoming these barriers under a comprehensive approach that combines science, technology, and community participation. Therefore, biogas is positioned as a key pillar for a circular, fair, and resilient bioeconomy, promoting energy security and advancing toward a just and environmentally responsible future.

1. Introduction

In a world where the ravages of climate change and pollution are felt daily, it is imperative to analyze what is happening and seek possible solutions to mitigate these effects. This is where the issue of waste management becomes relevant, representing a global challenge as it directly impacts the environment and public health. Proper management will reduce pollution, conserve natural resources, and mitigate global warming, ensuring a sustainable balance for future generations. However, it is necessary to begin by raising awareness about how humans manage solid waste, both individually and collectively, and what it is possible to do to reduce, recycle, and reuse it in our daily lives.

It is currently estimated that humans generate 2.24 billion tons of solid waste each year, whether from homes, businesses, industries, institutions, or public spaces; of this amount, 931 million tons is food waste alone and typically ends up in rivers and oceans, while only 55% is processed in controlled facilities [1].

According to data from the United Nations Environment Program’s Global Waste Management Outlook 2024 report [2], the generation of urban solid waste is expected to rise from approximately 2.3 billion tons reported in 2023 to 3.8 billion tons by 2050.

For the aforementioned reasons and due to the energy crisis, inefficient waste management, and climate change, urgent solutions are required; here, biogas has become a sustainable and efficient alternative. This renewable gas, generated by the anaerobic digestion of organic matter in the lack of oxygen [3], not only contributes to the reduction in waste and polluting emissions but also represents a key opportunity for economic and technological development in strategic sectors, such as agriculture and forestry [4], since the production of biogas from organic waste offers a multifaceted approach to addressing global challenges in waste management and the transition toward a more sustainable energy model.

It is estimated that around 1.3 billion tons of solid organic waste is generated annually in the agricultural and forestry sectors [5,6], increasing the need for efficient public policies and reducing the high initial implementation costs. The conversion of this biomass into biogas and biofertilizers not only minimizes the environmental impact but also optimizes the use of resources, strengthening biodiversity and soil quality through more sustainable agricultural practices [7,8].

Biogas, composed primarily of methane (CH₄) and CO₂, is a renewable energy source with significant potential for exploitation. Its versatility allows it to be used for generating electricity, heating, fueling vehicles, and even injection into natural gas networks. Its production involves various stages, such as the collection and pretreatment of raw materials, anaerobic digestion, and the separation of biogas and digestate, a nutrient-rich by-product that can be used as organic fertilizer. These processes have sparked growing interest in the scientific community and the energy sector, given their role in reducing dependence on fossil fuels and mitigating climate change [7,8,9].

However, challenges remain regarding its large-scale implementation. Factors such as the efficiency of the anaerobic digestion process, the variability of the waste used, and operating conditions can affect the economic and environmental viability of biogas compared to other renewable energy sources [10,11]. Therefore, it is essential to analyze current barriers to its development and identify innovative solutions that facilitate its adoption.

This review is framed within the global need for more efficient waste management, assessing the opportunities and limitations of biogas in the agricultural and forestry sectors. Through the analysis of various research papers addressing this topic, it seeks to offer tools for its practical application, proposing strategies to optimize its production and integration into local energy systems.

Ultimately, biogas production not only transforms waste into a clean energy source but also represents a key component in the circular economy and the fight against climate change. With its ability to transform environmental problems into sustainable solutions, biogas is establishing itself as an essential pillar in the transition toward a resilient, accessible, and more environmentally responsible future.

2. Technical Fundamentals of Biogas

Biogas is a type of renewable gas that can be produced from organic waste from various industries, such as forestry, agriculture, and livestock. Generally speaking, wherever decomposing organic matter exists, it is possible to generate this biofuel used worldwide as an energy source for both industrial and domestic purposes [12]. Biogas is mainly composed of CH₄, in a proportion of 50 to 70%, which gives its energy value; it also contains carbon dioxide (CO₂) and traces of other gases, such as hydrogen, nitrogen, and hydrogen sulfide [13]. This gas can be obtained through two main processes—anaerobic digestion, which consists of the biological decomposition of organic matter in the absence of oxygen, and thermochemical conversion, which transforms biomass through the application of high temperatures. The fundamental difference between the two processes lies in the type of biomass they use—anaerobic digestion is mainly applied to agricultural and livestock waste, which is rich in moisture and easily biodegradable, while thermochemical conversion is oriented toward the use of forest biomass, such as wood and other dry lignocellulosic waste [14,15]. Both alternative processes represent sustainability compared to the use of fossil fuels, such as coal and oil. In this context, it should be noted that depending on national nomenclature, the gas produced in thermochemical conversion may also have other names: pyrolysis gas and wood gas. This is important because, in some legal systems, biogas is defined solely as a product of anaerobic digestion.

The anaerobic digestion process consists of four main stages and is a biological method carried out in biodigesters (Figure 1).

Into the following list outlines each stage:

1. Hydrolysis; This stage is fundamental since it constitutes the first biochemical step in the transformation of complex organic matter (breaking down lipids, proteins, polysaccharides, and nucleic acids) into simpler compounds, such as amino acids, fatty acids, monosaccharides, and other low-molecular-weight compounds that can be used by methanogenic microorganisms. This involves the breaking of chemical bonds in macromolecules, releasing monomers that dissolve in the medium and become accessible to acidogenic and acetogenic bacteria in later stages [14,15,16,17]. The speed and efficiency directly affect the production and quality because hydrolysis prepares the substrate for subsequent fermentation and biogas production [18,19]. Some factors that affect this stage are (A) temperature since the enzymatic activity is optimal in mesophilic (30–40 °C) or thermophilic (50–60 °C) ranges, depending on the system; (B) the pH, which when neutral or slightly alkaline favors the activity of hydrolytic enzymes; (C) the particle size, that is, the smaller the particles, the greater the contact surface area and the faster the hydrolysis; and (D) the biochemical composition of the substrate since the proportion of lipids, proteins, and carbohydrates influences the decomposition rate [18,20]. Consequently, recent studies have shown that proper management of hydrolysis, including mechanical pretreatments, can prevent operational problems, such as matter accumulation, scaling, and blockages in biodigesters, in addition to improving the removal of organic matter and increasing biogas production [19].

2. Acidogenesis; During this stage, the products generated during hydrolysis, such as simple sugars, amino acids, and short-chain fatty acids, are fermented by acidogenic bacteria. This process gives rise to a mixture of compounds, including organic acids like acetic, propionic, and butyric acids; alcohols; CO₂; and hydrogen (H₂) [21]. In this phase, simple molecules are transformed into intermediate metabolites, mainly volatile fatty acids and gases, which act as a crucial bridge between initial depolymerization and methanogenesis. Its correct execution is key to the efficiency of the anaerobic digestion system [22]. The main microbial actors are facultative and strict anaerobic bacteria, for example, species of the genera Clostridium, Bacteroides, Peptostreptococcus, Lactobacillus, Enterobacter, and Escherichia [23], which use specific metabolic pathways that vary depending on the type of substrate and reactor conditions, generating different acid and gas profiles; the diversity and activity of these microorganisms are influenced by several factors, such as temperature (mesophilic: 30–40 °C; thermophilic: 50–60 °C), an optimal pH (5.5–6.5), the carbon/nitrogen ratio (C/N), and the hydraulic retention time (HRT). A critical aspect to consider in this phase is the presence and proportion of key metabolites. Acetic acid is essential for acetoclastic methanogenesis, while propionic and butyric acids require further conversion by acetogenic bacteria. Ethanol and methanol can fuel methanogenic pathways, and H₂ and CO₂ are essential for hydrogenotrophic methanogenesis. The proportion of these intermediates directly affects the CH₄ production rate. An excess of volatile acids can cause acidification of the system and halt the process. Therefore, it is essential to maintain a balance between acidogenesis and methanogenesis to avoid inhibitions [24,25,26]. Understanding and optimizing this phase has profound implications, such as improving energy efficiency, reducing GHG emissions, and enabling greater valorization of agricultural, urban, and industrial waste. Furthermore, the products generated in this stage are essential precursors for the next phase since they not only transform compounds but also define the quality and quantity of the substrate available for biogas generation [27].

3. Acetogenesis; This step acts as a metabolic link between the formation of organic acids (acidogenesis) and the final production of CH₄ (methanogenesis), which is essential to maintain the flow of carbon and hydrogen to methanogenic microorganisms [25]. It is here where volatile fatty acids (VFAs), such as propionic, butyric, valeric acids, and some alcohols, are oxidatively converted to acetic acid, H₂, and CO₂ by acetogenic bacteria [27]. Consequently, not only acetate, the main precursor of CH₄ in acetoclastic methanogenic pathways, but also H₂ and CO₂ are produced, which are used by hydrogenotrophic methanogenic archaea. Thus, acetogenesis is fundamental to the redox balance of the anaerobic system [28]. This process is endothermic under standard conditions but becomes viable when hydrogen is rapidly removed by methanogens [29,30]. The main factors that influence this stage are (A) an optimal pH since values below 6.5 and 7.5 affect the stability of the process; (B) temperature, preferably mesophilic conditions between 35 and 40 °C or thermophilic conditions at 55 °C, depending on the microbial consortium; (C) the hydraulic retention time (HRT), which, if too short, does not allow the bacteria to complete the transformation; (D) the concentration of VFAs and H₂ since excesses of propionate or butyrate indicate failures in acetogenesis; and, specifically, (E) the accumulation of propionate because it is considered a marker of instability and its conversion is most sensitive to environmental conditions [31]. The efficiency of acetogenesis ensures a reduction in the pollution load of waste and lower GHG emissions, resulting in fewer pathogens and odors and greater stability for decentralized energy uses.

4. Methanogenesis. This is the last stage, and its function is essential: it converts the products generated in previous stages, such as acetate, H₂, and CO₂, into CH₄, the main energy component of biogas. The three main methanogenesis routes are acetoclastic methanogenesis (CH₃COOH→CH₄ + CO₂), which uses acetate and accounts for 60–70% of the CH₄ produced; hydrogenotrophic methanogenesis (CO₂ + 4H₂→CH₄ + 2H₂O), which accounts for 25–35% of CH₄ and is crucial under low-acetate conditions; and methylotrophic methanogenesis (4CH₃OH→3CH₄ + CO₂ + 2H₂O), which is less common and occurs with alcohols and methylated compounds. These routes are thermodynamically favorable and allow methanogens to thrive in oxygen-free environments, closing the anaerobic digestion cycle [32]. These routes or archaea populations present a high sensitivity to changes in pH (the optimum is between 6.8 and 7.2; extreme fluctuations can inhibit enzymatic activity), temperature (two common ranges are handled: the first under mesophilic conditions with temperatures between 35 and 40 °C or thermophilic conditions, with ranges between 50 and 60 °C, favoring different microbial communities), and the partial pressure of hydrogen, so their viability depends on the balance achieved by previous stages, such as acetogenesis [25,33].

Integrated Optimization and Emerging Technologies

Anaerobic digestion (AD) is consolidating as a key technology for the energy recovery of agricultural and forestry waste, especially in the context of energy transition and the circular economy. This process offers a sustainable solution for reducing greenhouse gas emissions by transforming organic biomass into methane-rich biogas (CH₄), decreasing dependence on fossil fuels, and promoting rural development. However, its optimization faces multiple technical challenges, such as the low biodegradability of lignocellulosic biomass, the instability of microbial communities, and limitations in the quality of the biogas produced [34].

To overcome these challenges, integrated strategies have been developed that combine advanced pretreatments, high-efficiency reactors, precise microbial management, and emerging technologies aimed at maximizing methane production and purity. Among the most effective pretreatments are mechanical (milling, ultrasound), chemical (ozone, alkali, deep eutectic solvents), and biological methods, which aim to break down lignocellulosic structures that hinder microbial digestion. These treatments have been shown to significantly increase the hydrolysis rate and reduce the hydraulic retention time, thereby improving process efficiency [35,36,37,38].

In parallel, the choice of reactor type plays a crucial role in system efficiency. Technologies such as the upflow anaerobic sludge blanket (UASB), the continuous stirred tank reactor (CSTR), and anaerobic membrane reactors allow for greater active biomass retention, tolerance to high organic loads, and stable operation under adverse conditions [39,40,41].

Advanced microbial management represents another fundamental pillar for stabilizing and enhancing system performance. Using metagenomic techniques, the microbial composition can be monitored and adjusted in real time, promoting resilient syntrophic communities and desired metabolic pathways. Bioaugmentation, the controlled addition of specialized microbial strains, has been shown to be effective in improving the conversion of recalcitrant compounds and accelerating methanogenesis [42,43,44].

In this context, emerging technologies open up new possibilities for increasing both the quantity and the quality of biogas. One of the most promising technologies is direct electron transfer (DIET) stimulation, which facilitates electron transfer between microorganisms using conductive materials, such as biochar, activated carbon, or magnetite nanoparticles. This mechanism reduces dependence on intermediates, such as hydrogen (H₂), accelerates acetoclastic syntrophy, and improves the efficiency of methanogenesis, even under inhibitory conditions, such as the presence of heavy metals or antibiotics [33,45,46,47,48].

Furthermore, biogas upgrading is essential for its integration into natural gas networks or its use as a vehicle biofuel. Technologies such as membrane separation, physical absorption with water or amines, and pressurized anaerobic digestion have been shown to significantly improve biomethane purity (up to >98% CH₄). However, large-scale implementation of these technologies remains limited by high energy and operational costs [37,38,39,49,50,51]. Therefore, organizations such as the International Energy Agency [52] promote the development of modular, decentralized systems adaptable to local waste sources, with a special emphasis on rural and agricultural areas.

Within this same framework of decentralized energy transition, recent studies have explored integrated approaches to energy planning in rural and urban settings. One example is the development of a two-stage stochastic energy programming model for rural multi-energy microgrids (MERMs), which integrates irrigation systems and anaerobic biomass fermentation [53]. This model addresses uncertainty in variables such as precipitation, renewable energy generation, and electricity and heat demand using a stochastic mixed quadratic programming (SMIQP) approach combined with a scenario decomposition algorithm based on the progressive coverage (PH) method. Biomass fermentation is modeled with dynamic differential equations, while the irrigation system considers detailed meteorological data. The results show that this integration enables more efficient and resilient energy management in rural settings, underscoring the value of biogas production from agroforestry residues.

However, one study focused on the assessment and regulation of multitemporal security in integrated electricity and heat systems (IEHSs), with an emphasis on urban environments. This approach incorporates load prediction, power generation, and thermal storage models, operating on timescales ranging from seconds to days. While it does not directly address biogas production, it highlights the importance of integrating renewable energy and storage technologies to ensure the flexibility, stability, and security of the urban energy system [49].

Both studies share a common vision of the need to optimize complex energy systems under uncertain conditions, although they differ in their practical applications. While the first developed a model oriented to rural contexts with direct integration of anaerobic digestion and water management [53], the second focused on urban contexts, emphasizing multi-scale operational resilience [49]. Together, these works complement the technological approach of AD and reinforce the idea that its integration into hybrid energy systems can significantly contribute to energy sustainability and security.

In short, the energy recovery of agroforestry waste through anaerobic digestion and complementary technologies constitutes an effective strategy to face the challenges of climate change, promote rural development, and move toward a more resilient, decentralized, and sustainable energy model [34,35,54,55].

3. Bioenergy Potential and Classification of Agricultural and Forestry Waste

Agricultural residues (crop residues, straw, and manure) and forest residues (branches, bark, and sawdust) are considered strategic raw materials for biogas generation [36,56]. Their use not only contributes to mitigating environmental impacts by reducing dependence on fossil fuels and GHG emissions but also promotes energy decentralization, especially in rural regions, promoting the circular economy. This form of valorization is considered one of the most promising technologies for the efficient management of organic waste from rural and forestry origins [57].

3.1. Forest Waste

The most common forest waste includes stems, leaves, bark, chips, branches, and others, which contain biomass rich in cellulose, hemicellulose, and lignin, which are compounds that can be converted into energy. In Mexico, forestry production generates large volumes of wood and non-wood waste, which can be used to generate bioenergy. These wastes are considered renewable, as they can be replaced through sustainable forestry activities. The energy potential is significant, with estimates indicating the possibility of generating up to 65.6 GWh per year in certain regions using technologies with a minimum efficiency of 40% [58,59].

3.2. Agricultural Waste

While agricultural waste is abundant and varied, crops such as potatoes, corn, and tomatoes produce post-harvest waste with a considerable energy potential. In Ecuador, tomato waste has a higher energy potential (0.54 GWh) compared to potatoes and corn due to the greater amount of available residual biomass [60]. This potential is directly proportional to the amount of residual biomass generated, as these organic materials are ideal for biogas production due to their high availability and chemical composition suitable for anaerobic digestion. Co-digestion of agricultural waste with other types of biomass, such as animal manure, can improve process efficiency by balancing essential nutrients for anaerobic bacteria [61,62].

3.3. Biogas Potential at a Global Level

Therefore, in a global context, its technical potential for generating biogas and, in turn, energy far exceeds current production, although its use requires integrated strategies that consider geographic availability, conversion technologies, and regulatory frameworks.

Global biogas and biomethane production is estimated at 400 TWh per year, equivalent to 1% of the natural gas consumed, but its technical potential would reach 8000 TWh, enough to replace 20% of the current natural gas demand and avoid 1.5 gigatons of CO₂. Europe leads production with 215 TWh, followed by China with 87 TWh, although only 10% of European biogas is converted into biomethane suitable for gas networks [63]. Therefore, agricultural and forestry residues are key due to their high availability. For example, anaerobic digestion of these materials generates biogas with 55–70% CH₄, usable for electricity, heat, or renewable fuel [64].

Analyzing a little about the potential by region, it can be mentioned that in Latin America, Argentina has a potential of 1360,000 m³/day of biogas using corn, wheat, soybean, and pig and cattle waste, equivalent to 38% of the national energy deficit [65]; Chile could install 400 MW of electrical capacity with biogas (3.5% of the current matrix), highlighting 150 MW as feasible with existing reactors to treat industrial waste [66], while Colombia, specifically in Cundinamarca, the potential reaches 1,117,567 TJ/year, mainly from coffee, sugarcane, and cattle waste, with priority areas like Fómeque and Anapoima [64].

However, in Europe, specifically in Spain, the National Integrated Energy and Climate Plan (PNIEC) proposes to increase the use of biomass in cogeneration to 1408 MW by 2030, using pruning remains and forest biomass. In addition, biomethane injected into gas networks already has 10 operating plants and 200 projects under development [67].

The aforementioned information leads to a global comparative analysis of the transition toward sustainable energy systems that requires maximizing the potential of underused resources, highlighting the disparities between theoretical capacity and actual use. For Mexico, the data reveal a critical gap: although its biomass resource could cover 46% of the primary energy demand, less than 5% is currently used.

Table 1. Bioenergy potential of agricultural and forestry residues worldwide.

Region/Country	Agricultural Global [68,69,70]	Ethiopia [71]	United States [70]	EU [69,70,71,72]	Germany (NRW) [73]	Brazil [70]	Mexico [74,75,76]
Waste type	Crop residues	Corn/sorghum residues	Forest waste	Mixed waste	Cereal residues	Cane bagasse	Mixed waste
Energy potential	64–161 EJ/year (2050)	559–1144 PJ/year	41 M tons/year ≈ 3.2 B gallons of oil	30–50 EJ/year (2030)	15–25 PJ/year	18–22 EJ/year	1030–3569 PJ/year
Current contribution	<5% of the exploited potential	Local use in rural areas	15–20% used in bioenergy	10–15% in advanced biofuels	Used in rural heating and electricity	70% used in cogeneration	<5% used
Environmental advantages	Reduces CO2 by 40% vs. open burning Prevents 89% of particulate matter (PM10) emissions	Mitigates in situ burning (pollution) Improves soil management	Reduces fire risk Biochar improves water and nutrient retention	Closed-loop carbon neutrality Reduces dependence on fossil fuels	Maintaining organic matter in soils Reducing synthetic fertilizers	Replaces diesel in machinery Reduces pre-harvest burning	Mitigates 110 Mt CO2 annually (2030) Reduces water/air pollution
Main challenges	Competition with food uses Loss of organic carbon in soils	Limited infrastructure Lack of efficient logistics chains	Transportation costs Low profitability in remote areas	Sustainability certification Competition with other industrial uses	Immature markets Requires adjustments to crop rotation	Intensive monoculture Pressure on water resources	Lack of logistical infrastructure Competition with traditional agricultural uses
Key technologies	Biorefineries, gasification, pyrolysis	Anaerobic digestion, gasification	Fast pyrolysis, roasting	Hydrotreating (HVO), lignocellulosic fermentation	Biochar, optimized harvesting systems	Combustion in boilers, 2G bioethanol	Gasification, anaerobic digestion, combustion
Featured cases	Projects in the EU and the United States for cellulosic ethanol and HVO	National bioenergy plan with a focus on regions such as Oromia (45% of potential)	Projects in California for conversion to biochar and electricity	SAF production in refineries, such as EcoCeres (1000 tons/day)	Integrated projects with cover crops to balance carbon	Integrated plants in São Paulo for bioelectricity	Sugar mill projects for cogeneration

summarizes key data on the use of agricultural and forestry residues, organized by region, waste type, and technical variables. It integrates comparative energy potential scales (PJ/EJ), current use rates (<5% in Mexico vs. 15–20% in the United States), critical variables contributing to climate mitigation, viable technologies (pyrolysis, gasification), and logistical challenges, as well as unique cases ranging from anaerobic co-digestion in Mexico to advanced biofuels in the EU [68,69,70,71,72,73,74,75,76].

Table 1 identifies synergistic opportunities and warns of systemic risks, such as the loss of organic carbon in soils due to overexploitation. Its creation is intended to facilitate the analysis of public policies based on the criteria of efficiency, sustainability, and territorial equity while also providing a quantitative basis for prioritizing investments in the circular bioeconomy.

Bioenergy derived from agricultural and forestry residues is emerging as a strategic solution to diversify the global energy matrix, with particular relevance in megadiverse countries such as Mexico. Globally, agricultural residues have an energy potential of 64–161 EJ/year by 2050, although less than 5% is currently exploited [70]. In contrast, Mexico has a theoretical national potential of 1030–3569 PJ/year in agricultural and forestry residues alone, equivalent to 46% of its primary energy supply [74], although its effective use does not exceed 5% [75].

In particular, the Mexican forestry sector stands out with an estimated energy potential of 2980 PJ/year, where 58% comes from forests and 27% from agricultural waste [75]. However, critical challenges persist, such as availability in contrast to actual access; although spatial models identify productivities of up to 18 GJ/Mg in forests [70], factors such as slopes >30% and protected natural areas reduce the theoretical sustainable potential (TSP) [70]. Another challenge could be underused technologies since gasification and anaerobic digestion are key to processing wet waste, such as bagasse (19.40 MJ/kg) [77], and in that country, there is a lack of industrial-scale infrastructure outside of sugar mills [74]. Since optimal waste use would have a climatic impact, potentially mitigating 110 Mt CO₂/year by 2030 [75], excessive extraction (>30% of waste) would reduce soil organic carbon by 0.2–0.5 t/ha-year [74].

In contrast to global trends and lessons learned, while the EU is moving forward with advanced biofuels (hydrotreating for SAF) and the United States is optimizing catalytic pyrolysis for forest residues [75], Mexico requires specific policies on hybrid models combining anaerobic digestion (e.g., manure + rice husk, 48.9% CH₄) [77] with mobile torrefaction systems for remote areas, as well as integrated certifications to develop sustainability standards that include water balances and biodiversity, particularly in regions such as the Sierra Madre Occidental [74].

Although Mexico’s bioenergy potential represents a window into meeting climate and rural development goals, its success depends on (1) institutional synergies to align programs like SAGARPA-SENER with local initiatives to create efficient supply chains, (2) contextualized innovation to adapt technologies like modular biorefineries to the geographic and socioeconomic conditions of regions like Veracruz and Durango, and (3) comprehensive monitoring to implement waste traceability systems that guarantee the sustainability of the resource without compromising food security.

Therefore, global experience demonstrates that the bioenergy transition requires precise balances between energy use and ecosystem conservation; for Mexico, this path involves not only adopting technologies but also redefining its relationship with natural resources from a regenerative perspective.

4. Environmental Impacts, Socioeconomic Opportunities, and Implementation Frameworks

Addressing the importance of environmental impact, biogas produced from agroforestry waste represents a renewable energy alternative with positive environmental and socioeconomic impacts.

The main significant benefit is the reduction in GHG emissions by replacing fossil fuels. Biogas can replace natural gas, diesel, or even firewood used in traditional stoves, reducing the emission of CO₂, CH₄, and nitrogen oxides; it can reduce emissions associated with energy generation in decentralized systems by up to 80% [78]. Furthermore, organic waste management becomes more sustainable since, instead of being burned or abandoned, agroforestry residues are valorized through anaerobic digestion. Likewise, the digestate generated can be used as organic fertilizer, closing the nutrient cycle and reducing dependence on synthetic fertilizers [79,80]. Figure 2 presents a comparison showing GHG emissions by fuel type, expressed in kilograms of CO₂ equivalent per MWh produced, noting that biogas generated from agricultural and forestry waste has significantly lower emissions compared to traditional fossil fuels.

The transition from fossil fuels to renewable bioenergy sources, such as biogas, represents a crucial step toward reducing global GHG emissions.

Fossil fuels, such as coal, diesel, and natural gas, emit significant amounts of GHGs during their extraction, processing, and combustion. In contrast, biogas derived from agricultural and forestry residues offers drastically lower emissions. This is due to both the capture of CH₄ (a potent GHG) during anaerobic digestion and the recycling of organic waste that would otherwise release emissions during decomposition. The data highlight how replacing fossil fuels with biogas can lead to reductions of up to 90% in GHG emissions, depending on the feedstock and system efficiency.

From a socioeconomic perspective, the impacts are equally relevant. In rural areas, biogas production offers clean and affordable energy, biofertilizers, and local employment opportunities in harvesting, system operation, and maintenance. This contributes to strengthening energy security, improving soil quality, and fostering local economic development [81,82]. To objectively assess these benefits, sustainability indicators like the ecological footprint, net GHG reduction, system energy efficiency, and community well-being are used. Studies highlight that well-implemented biogas systems have a significantly lower carbon footprint compared to conventional energy sources [83]. Together, these benefits position biogas not only as an energy transition technology but also as an integral tool for sustainable development in agricultural and forestry settings.

Considering that biogas offers a wide range of socioeconomic opportunities that can drive sustainable development, particularly in rural and peri-urban areas, in addition to its potential for integration with other productive sectors, these opportunities are framed in four main dimensions: technological, economic, political, and social.

Figure 2. GHG emissions by fuel type. Source: adapted from [78,79,80,83].

Figure 2. GHG emissions by fuel type. Source: adapted from [78,79,80,83].

4.1. Technological Opportunities: Accessibility, Scalability, and Maintenance

Anaerobic digestion technologies have advanced significantly, allowing their adaptation to different scales, from small-family biodigesters to industrial plants. These technologies have become increasingly accessible and adaptable to different climatic and socioeconomic conditions. Furthermore, many of these technologies have been simplified to facilitate local maintenance, allowing their adoption by rural communities with limited technical levels [84]. Furthermore, the modularity of the systems allows them to be scaled according to waste availability and energy demand [85]. This is especially relevant in rural areas, where access to sustainable energy solutions is limited. Figure 3 compares four world regions—Africa, Asia, Latin America, and Europe—in terms of the estimated level of accessibility, scalability, and maintenance of biogas technologies.

These dimensions are key to assessing the adoption potential of biodigesters and anaerobic digestion systems based on agricultural and forestry residues [79,85]. Africa presents moderate-to-high barriers, especially in technical maintenance, due to limitations in infrastructure and trained human resources. These conditions have been documented in various reports on the limited expansion of biogas in rural African areas [84]. Asia shows high levels of implementation, especially in accessibility and scalability, thanks to the leadership of countries such as China and India in rural biogas technologies. This expansion has been facilitated by public policies and government incentives [85]. Latin America has a favorable context with intermediate technological development and growing investment, although it still faces challenges in maintaining community systems, as noted by initiatives led by cooperation agencies and regional studies [79]. Europe leads the way in all three areas, with mature technological networks, strong institutional support, and established bioenergy markets. The region has promoted biogas use through robust regulatory frameworks and certification schemes [84].

4.2. Economics: Initial Investment, Profitability, and Subsidies

From an economic perspective, although the initial investment can be challenging, especially in low-income contexts, several studies have shown that biogas systems are profitable in the medium term, especially when considering benefits such as the use of digestate as fertilizer, reduced energy costs, and waste use [10,12,81,82,86]. Furthermore, several countries offer subsidies, tax incentives, and green financing programs to drive the adoption of these technologies [79]. The comparison of five world regions on three key economic factors for biogas development—initial investment, profitability, and subsidy availability—is shown in Figure 4.

Each factor is expressed as an index (0–100), with higher values representing better performance or greater support in that area. “Initial investment” refers to the capital needed to implement biogas systems. Regions with lower scores (e.g., Africa) face greater financial barriers due to a lack of infrastructure or access to credit [79]. Cost-effectiveness considers operational returns, including energy savings and by-products (such as biofertilizers). Europe and North America lead this category, thanks to mature markets and integration with circular economy policies [87]. Subsidies reflect available government or institutional support. Europe has the highest value, driven by strong renewable energy incentives and emissions reduction targets [85].

4.3. Policies: Regulatory Framework, Incentives, and Certifications

At the political level, a clear regulatory framework is essential for the success of biogas projects. Some countries have developed specific regulations, incentives, and certification programs that recognize biogas as a clean energy source and a fundamental part of the energy transition. Implementing these energy standards has facilitated the sector’s growth through support, such as economic support, feed-in tariffs, and favorable environmental regulations [87,88]. For example, the European Union includes biogas in its circular economy and rural energy strategy [89]; another strategy is sustainability certifications that add value to derived products, facilitating their commercialization and acceptance in specialized markets. Figure 5 presents a comparison of five world regions and the political factors related to biogas.

These factors are critical to facilitating the widespread adoption of biogas technologies and are expressed as estimated indices (0–100). Regulatory frameworks include national or regional laws, environmental regulations, and permitting procedures governing biogas systems. Europe leads the way with strong and harmonized policies, such as the EU Renewable Energy Directive [85]. Incentives include subsidies, feed-in tariffs, tax credits, or public–private financing schemes that reduce financial barriers to adoption. Europe and North America offer strong financial incentives, while Africa still faces significant gaps [87,88]. Certifications ensure compliance with quality, sustainability, and safety standards in biogas systems. They are most developed in Europe and North America, where they are linked to renewable energy targets and carbon credit markets [84]. As shown in Figure 5, it is possible to see where strategic improvements are needed to unleash the biogas potential in less developed regions and support sustainable energy transitions globally.

Table 2. Summary of key parameters in biogas production in different regions of the world across Africa, Asia, Latin America, Europe, and North America.

Region	Country	Biogas Yields (Approx.)	Policy for Biogas Production	Economic Factors Influencing Biogas Production, Trade, or Frequent Applications
Africa [63,90,91,92,93,94,95,96]	South Africa	18 million m3 per year	The African Biogas Partnership Program (ABPP), supported by the Netherlands Development Organization (SNV), is actually helping to push biogas development in Uganda, Kenya, Tanzania, Ethiopia, and Burkina Faso through the lens of quality standards, performance-based financing, public awareness, and policy advocacy.	Elevated loan interest rates reduce the financial feasibility of biogas projects; central bank interest rates range from 14% to 17%; the cost of installing conventional biogas systems.
	Nigeria	6.8 million m3 per day
Asia [97]	China	13,480 million m3 per year	The 14th Five-Year Plan for the Modern Energy System, National Energy Administration, 2022; Demonstration Counties for Rural Energy Revolution, 2023; Administrative Measures for Voluntary Emissions Reduction Trading of Greenhouse Gases, 2023.	Biogas-based electricity production, the use of biomethane as fuel for vehicles or industry, injection of biomethane into the gas network, and conversion of biogas into hydrogen or synthetic methane.
Latin America [63,97]	Santiago de Chile	24 million m3 per year	Some of the Brazilian laws and policies are the Distributed Generation of Electricity Law 14.300/2022; the Biomethane Production Law 14.134/2021 or the New Law of Gas; the National Biofuels Law—Federal Law 13.576/2017 or RenovaBio; and At COP 26 (2022).	Using biodigesters helps alleviate poverty; lowers the costs for fuel, organic fertilizers, and food; enhances household sanitation; and supports environmental sustainability. In Brazil, most biogas is converted into electricity.
	Brazil	2.3 billion m3 per day
Europe [97]	Germany	87,110 (GWh/year)	Germany introduced a coal phase-out program in 2018, targeting a complete exit by 2038, followed by a climate policy package in 2019. A key measure driving the country’s energy transition is the Renewable Energy Sources Act (EEG), the federal government directive to formulate the National Biogas Strategy (NABIS).	It is used more in electricity and fuel for cars.
	United Kingdom	32,000 (GWh/year)	The policies in the United Kingdom are related to anaerobic digestion: pollution control grants, the Renewables Obligation Scheme, feed-in tariffs (FiTs), and renewable heat incentives (RHIs). Some other policies related to the biogas sector are the Green Gas Support Scheme (GGSS), the Renewable Transport Fuel Obligation (RTFO), and separate food waste collection.	To generate electricity, heat, and biomethane production.
North America [63,97,98]	United States	18,500 million m3 per year	Key policy tools in the United States include a mix of federal and state initiatives, such as the Renewable Fuel Standard (RFS), the Inflation Reduction Act (IRA), and various state-level renewable portfolio standards (RPS).	The majority of biogas in the United States and Canada is used in electricity-only plants, with some also used in combined heat and power (CHP) systems.
	Canada	22 Pj per year	Support for anaerobic digestion at the federal level in Canada is minimal—the Agricultural Clean Technology Program and feed-in-tariff programs.

summarizes key parameters such as biogas yields, policy support, and techno-economic feasibility across Africa, Asia, Latin America, Europe, and North America.

More than half of the biogas production is concentrated in a few European countries, with an estimated volume of 215 TWh, and about 25% is located in China, with 87 TWh [63]. Furthermore, the global electricity generation capacity from biogas was 2455 MW in 2000, and in the following two decades, there has been a notable proliferation of biogas plants, reaching an installed capacity of 20,150 MW in 2020 [85]. Germany, the United States, the United Kingdom, Italy, China, France, and Brazil are the seven countries that concentrate 73.8% of the biogas electricity production plants in the world.

4.4. Social Opportunities: Acceptance, Technical Knowledge, and Training

At the social level, community acceptance of biogas tends to be positive when accompanied by awareness raising and technical training. Community ownership of the technology depends largely on the end users’ knowledge of its benefits, maintenance, and economic potential. Participatory implementation programs that involve end users in system design and operation have proven to be more sustainable and resilient in the long term. This opens up opportunities for technical training and local capacity-building programs (Figure 6), fostering a sense of ownership and ensuring the system’s proper functioning [99,100].

Social acceptance reflects community support, public perceptions, and willingness to adopt biogas technology. It tends to be highest in Latin America and Europe, where public awareness programs have been most active [79]. Technical knowledge includes the availability of trained professionals and a level of familiarity with biogas systems. Europe and North America show higher values, while Africa still faces significant capacity gaps [100]. Training and education encompass formal and informal initiatives targeting farmers, technicians, and local stakeholders. Investment in human capital has been key to the success of biogas in Europe and Asia [85]. These results suggest that improving education, awareness, and community participation is essential for the success of biogas projects, especially in low-income regions.

4.5. Global Route for Biogas Implementation

The implementation of biogas derived from agricultural and forestry waste contributes significantly to reducing greenhouse gas (GHG) emissions, closing nutrient cycles, and generating sustainable energy, especially in rural and peri-urban areas.

Table 3. Roadmap addressing technological, political, economic, and social dimensions.

Phase	Key Actions	Actors Involved	Expected Results
Phase 1: diagnosis and planning [77,78,81,89,90]	Assessment of available waste, identification of local stakeholders, regulatory and financial diagnosis	Local governments, universities, NGOs	Map of opportunities for biogas
Phase 2: technological development and pilot [81,82,83]	Installation of pilot biodigesters, technical and socioeconomic validation, initial training	R&D centers, rural communities, private sector	Replicable models adjusted to the local context
Phase 3: scaling and financing [78,80,81,86]	Regional expansion of successful systems, access to financing, subsidies and tax incentives	Financial institutions, national governments, cooperation agencies	Increase in rural energy coverage
Phase 4: integration into public policies [10,82,84,88,89]	Inclusion of biogas in national climate and energy plans, development of robust regulatory frameworks	Ministries of Energy and Environment	Consolidation of biogas as a pillar of the energy transition
Phase 5: monitoring and continuous improvement [78,80,81,86]	Impact assessment, technology upgrade, community strengthening	Civil society, academia, governments	Sustainable systems with high climatic and social impact

presents a roadmap that integrates actions across four dimensions—technological, political, economic, and social—with an articulated vision of sustainable development and the circular economy.

The implementation of biogas produced from agricultural and forestry waste requires a comprehensive and phased approach that combines technological innovation, robust regulatory frameworks, economic viability, and community engagement. This multidimensional roadmap not only allows solutions to be tailored to local contexts but also drives a fair and sustainable energy transition, consolidating biogas as a key tool for rural development and climate change mitigation.

5. A Global and Transdisciplinary Approach to the Challenges, Knowledge, and Future Prospects of Biogas Production from Agricultural and Forestry Waste

Technical, economic, and regulatory challenges persist that limit the large-scale implementation of biogas; therefore, the main knowledge gaps, critical challenges, and priority research lines identified in recent years are summarized here.

5.1. Knowledge Gaps

Anaerobic digestion of lignocellulosic waste faces several scientific and technical challenges that limit its efficiency and large-scale application. One of the main challenges is the characterization of lignocellulosic substrates since their chemical composition, particularly the carbon-to-nitrogen (C:N) ratio and lignin content, varies considerably, depending on the crop type, harvesting method, and climatic conditions [14,99,100]. This heterogeneity affects process stability and hampers consistent biogas production, so detailed characterization is required to optimize digestion parameters [101,102]. Added to this is the limited understanding of the microbial dynamics involved in the process, as the lack of knowledge about the structure and function of microbial communities impedes the development of more robust and efficient biocatalysts [101,102]. Another critical aspect is the lack of knowledge about the effective integration of biochemical and thermochemical technologies within biorefineries, which is key to maximizing the production of biogas and other bioproducts [101,102]. Furthermore, significant gaps remain in the standardization and availability of waste data, including the quantification of fugitive methane emissions during storage and handling, as well as the long-term assessment of the use of digestate-derived biofertilizers. These emissions, if not properly controlled, can compromise the climate benefits of biogas [103,104]. The absence of a unified global system for accurately quantifying the production, composition, and spatial distribution of agricultural and forestry residues hampers the strategic planning of biodigesters and the optimization of the entire biogas value chain [14,99,103].

5.1.1. Current Critical Challenges

Among the critical challenges currently facing energy recovery from waste through anaerobic digestion, the low efficiency in converting lignocellulosic waste into biogas stands out, limiting the economic viability of the process. This is due to the structural strength of these materials and the need for more effective and economical pretreatments, as well as improvements in enzymology to increase methane production [101,102]. Furthermore, ammonia inhibition, common in nitrogen-rich waste, such as manure, can reduce methane production by up to 40%, while the thermal and chemical pretreatments required to enhance degradation increase energy costs by 15–30%, further compromising the system’s profitability [103,105]. Second, high production costs associated with both the construction and operation of the plants and the logistics of waste collection and transportation represent significant barriers to their implementation, especially in rural areas where transportation from dispersed areas can represent between 35 and 50% of operating costs [101,104]. This situation is exacerbated in rainfed agricultural sectors, such as coffee, where the harvest is concentrated in just four months of the year, generating prolonged periods of inactivity in biodigesters [101,105]. The lack of adaptive financial models and technical training also affects the sustainability of projects, as reflected in the fact that only 12% of plants in low-income countries remain operational for more than five years [104,106]. Finally, the absence of a clear regulatory framework and effective incentive policies hinders investment and the widespread adoption of these technologies. It is urgent to establish consistent regulations and economic incentives that favor their development and application [101,102].

5.1.2. Future Lines of Research

Progress in waste-to-energy recovery through anaerobic digestion (AD) is supported by multiple lines of technological innovation and public policy. First, the development of advanced biocatalysts, through the engineering of microorganisms and enzymes, promises to significantly improve the efficiency of AD, especially in the degradation of lignocellulosic materials [101,102]. In parallel, the optimization of integrated biorefineries that combine biochemical and thermochemical processes maximizes the production of biogas and other value-added coproducts, increasing the profitability of these systems [101,102]. Process modeling and simulation, using advanced computational tools, facilitates the design and operation of more efficient plants [101,102] and is complemented by the application of artificial intelligence, such as predictive platforms that integrate satellite, climate, and waste composition data to optimize the location and design of facilities [103,104], as well as the use of portable NIR spectroscopy for rapid in situ analysis of critical parameters, such as humidity and the C:N ratio [101,105]. Sustainable pretreatment technologies are also being developed, including low-cost enzymatic methods using ligninolytic fungi that reduce the forest waste hydrolysis time by up to 50% [103,104] and co-digestion with microalgae, which improves the nutrient balance and increases methane production by 25–35% [104,106]. A systemic approach promotes integrated circular economy models, such as connecting biodigesters with hydroponic systems to reuse 100% of the effluent as an agricultural nutrient [103,104] or converting residual CO₂ into synthetic fuels using power-to-gas technologies [104,107]. Finally, the development of innovative public policies is key, including international certification schemes for biofertilizers with traceability and a carbon footprint [103,104], as well as mixed public–private financing mechanisms that promote community plants in marginalized agricultural areas, strengthening energy resilience and rural development [104,106].

6. Conclusions

The energy use of organic agricultural and forestry waste through biogas production represents a strategic and multifaceted path to addressing the environmental, social, and economic challenges of the 21st century. This approach not only responds to the urgent need to mitigate climate change but also aligns with the principles of circular economy, ecological regeneration, and inclusive rural development. In this context, biogas is positioned as a concrete tool for rethinking the human relationship with waste and transforming environmental liabilities into energy and social assets.

Integrating this technology into public policies and sustainable development agendas is more than an energy alternative—it is a real opportunity to build more resilient, equitable, and decentralized systems. Biogas derived from agroforestry residues reduces greenhouse gas emissions, recovers essential nutrients for agriculture, and generates direct economic benefits in rural communities. Furthermore, its implementation can significantly contribute to achieving several Sustainable Development Goals, including those related to affordable and clean energy (SDG 7), climate action (SDG 13), responsible production and consumption (SDG 12), and decent work and economic growth (SDG 8).

From a technical perspective, anaerobic digestion is a mature technology, but its optimal performance depends on multiple factors—from the precise characterization of substrates and appropriate system design to the ability to adapt to diverse socio-environmental contexts. This requires the strengthening of local technical capacities, promoting applied research, and fostering participatory governance schemes that include community, industrial, and government stakeholders.

However, it is crucial to avoid reductionist or technocratic views. Bioenergy derived from agroforestry residues is not a miracle solution, but it is a realistic and necessary alternative in the transition toward sustainable energy systems. It is estimated that if properly implemented, it could mitigate up to 110 Mt of CO₂ annually by 2030 while boosting rural employment, improving the quality of life, and strengthening the energy sovereignty of producing regions.

In conclusion, unleashing the true potential of biogas requires a comprehensive approach that articulates science, technology, public policies, the social economy, and environmental justice. Only through informed and collaborative decisions will it be possible to move toward a cleaner, fairer, and more resilient energy matrix, thus redefining our relationship with waste and the territories that generate it.