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Article

Evaluation of Energy Potential in a Landfill Through the Integration of a Biogas–Solar Photovoltaic System

by
Héctor Alfredo López-Aguilar
1,*,
Guadalupe Kennedy Puentes
2,
Luis Armando Lozoya Márquez
3,
Oscar Chávez Acosta
4,
Humberto Alejandro Monreal Romero
5,
Claudia López Meléndez
1 and
Antonino Pérez-Hernández
3
1
Faculty of Agrotechnological Sciences, Universidad Autónoma de Chihuahua, Chihuahua 31160, Mexico
2
Department of Enginnering, Universidad la Salle Chihuahua, Chihuahua 31207, Mexico
3
Centro de Investigación en Materiales Avanzados, Chihuahua 31136, Mexico
4
Postgraduate Coordination, Instituto Tecnológico de Chihuahua II, Chihuahua 31130, Mexico
5
Faculty of Odontology, Universidad Autónoma de Chihuahua, Chihuahua 31000, Mexico
*
Author to whom correspondence should be addressed.
Urban Sci. 2025, 9(1), 17; https://doi.org/10.3390/urbansci9010017
Submission received: 14 November 2024 / Revised: 18 December 2024 / Accepted: 2 January 2025 / Published: 14 January 2025
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Abstract

:
The integration of biogas and photovoltaic solar energy systems in sanitary landfills represents a promising strategy for sustainable energy generation and efficient urban waste management. This study evaluates the potential for biogas and photovoltaic energy production in two cells of the Municipal Landfill of Chihuahua, Mexico. Using the LandGEM and MMB models (Landfill Gas Emission Model and the Mexican Biogas Model), biogas generation was estimated by considering the composition of the landfill gas and the characteristics of the cover in each cell, revealing notable differences due to their operational periods and waste deposition. Photovoltaic simulations, conducted with the HelioScope software 2020, evaluated spatial configurations and solar radiation data. The generation potential for 2025 was simulated using predictive models, yielding results between 25.48 and 26.08 MW for the biogas–photovoltaic system, depending on the orientation of the panels and the optimization of the coverage. The novelty of this work lies in the combined evaluation of biogas and photovoltaic potential within a single landfill site, integrating advanced modeling tools to optimize system design. By demonstrating the feasibility and benefits of this hybrid system, the study contributes to clean energy solutions, environmental mitigation, and improved waste management strategies. Our findings emphasize the importance of site-specific management practices and predictive modeling to enhance renewable energy production and reduce greenhouse gas emissions, supporting sustainable urban development initiatives.

Graphical Abstract

1. Introduction

In developing countries, while sanitary landfills are the primary method for municipal solid waste (MSW) disposal, their anaerobic decomposition generates leachates, volatile compounds, and gases that harm the surrounding ecosystem, highlighting the potential of anaerobic digestion of biodegradable materials as a sustainable alternative for waste management and biofuel production.
In Latin America, the underutilization of landfill biogas potential is evident, as the number of operational biogas power plants remains disproportionately low compared to the region’s available capacity for biogas generation [1,2].
The utilization of biogas generated in sanitary landfills (SLs) offers several advantages: (i) significantly reduces greenhouse gas emissions resulting from the decomposition of solid waste; (ii) serves as a sustainable alternative to fossil fuels for zero-emission energy generation; (iii) enhances the containment and treatment of leachates; and (iv) facilitates compliance with international regulations, promoting more efficient and comprehensive management of municipal solid waste. The biogas obtained from MSW is a mixture of methane, carbon dioxide, and non-methane organic compounds (NMOCs). Both carbon dioxide and methane are significant greenhouse gases, with methane being especially relevant due to its global warming potential, which ranges between 28 and 36 [3]. NMOCs, produced from the anaerobic decomposition of organic compounds and the combustion of fossil fuels, can contribute to the formation of tropospheric ozone, presenting risks to human health. Among these compounds, volatile organic compounds (VOCs) are particularly dangerous due to their high toxicity to both human health and the environment, although they are generally found in low concentrations in the atmosphere. Hazardous VOCs include benzene, toluene, xylene, hexane, vinyl chloride, and ethylbenzene, all of which are classified as hazardous air pollutants.
According to Verma et al. (2022), urban waste management practices, including composting and the recycling of MSW, result in direct greenhouse gas (GHG) emissions [4]. However, these practices have significantly mitigated a considerable amount of GHG emissions on a net basis. Additionally, GHG emission data provide valuable insights for developing more effective climate change mitigation policies and strategies. The production of methane after the closure of a landfill can provide primary fuel that makes the implementation of combined cycle power plants, which use biogas as fuel, feasible [5]. Furthermore, the timing of biogas system installation plays a pivotal role in maximizing methane capture and mitigating global warming potential, as evidenced by a study conducted in Iran [6]. In Italy, the integration of renewable energy solutions within waste management facilities resulted in notable reductions in environmental impacts, although some methods, like gasification, increased carbon emissions [7].
Various studies have estimated the quantity of gases produced in a landfill, demonstrating that it is feasible to predict gas production using theoretical modeling methods. The first-order decay model is widely recognized as the most commonly employed approach [8]. Despite advances in estimating the biogas generated in landfills, discrepancies in the models used and their accuracy are to be expected due to the interplay of various fluctuating factors. Several studies agree that the Landfill Gas Emission Model (LandGEM) is suitable for predicting methane and other GHG emissions from landfills [9,10,11]. However, Scheutz et al. (2022) found that LandGEM resulted in a significant overestimation due to its predetermined values for biochemical methane potential and the methane generation rate constant, which were too high for landfills with low organic waste content [12].
According to Srivastava and Chakma (2020), the LandGEM model produced moderate methane emission estimates, though with significant uncertainties [13]. These uncertainties are attributed to variability in MSW deposition data, gas generation rates, and the methane generation potential of landfill waste. Additionally, it has been found that the Mexican Biogas Model (MMB) provides a better fit to Mexican scenarios [14]. When comparing the LandGEM and MMB models, similarities in their equations were identified; however, the MMB provided a more accurate average biogas estimation with a better statistical fit [15].
According to other authors, the IPCC model is also appropriate for methane estimation [12], but in some cases, it produces significantly higher estimates, distorting biogas generation data [16,17].
Gas permeability in landfills is a critical parameter influencing the migration and management of landfill gases. Empirical studies indicate that the air permeability of municipal solid waste (MSW) within landfills varies between 1.6 × 10−13 and 3.2 × 10−11 m2, with the permeability decreasing significantly at greater depths [18]. This variability is influenced by factors such as waste composition, compaction, and moisture content. Additionally, a distinct relationship between gas permeability and volumetric gas content in MSW has been identified [19]. The final cover layer plays a critical role in controlling gas emissions generated by the decomposition of organic matter, emphasizing its importance within landfill gas management strategies [20]. Moreover, the integration of high-permeability layers beneath landfill covers has been shown to significantly reduce methane emissions by promoting uniform gas distribution and enhancing oxidation processes. This approach is particularly advantageous in heterogeneous landfills, where variable gas permeability can hinder effective gas management [21].
In addition to biogas, photovoltaic (PV) solar energy is proving to be key in reducing the use of fossil energy and supporting the Sustainable Development Goals (SDGs, numbers 7 and 13). Solar panels require space, making the reuse of closed landfills a viable solution, as they do not require high-quality land [22]. Integration with pre-existing electrical grids and road networks allows for the efficient transfer of substantial amounts of generated electricity, providing a significant cost advantage to landfill-based PV systems compared to conventional systems installed on new land [23]. Landfills present significant potential for solar PV development, effectively transforming waste sites into renewable energy assets. Such initiatives not only generate revenue to offset landfill maintenance costs but also contribute to the conservation of natural lands. Landfills are increasingly repurposed for solar energy development, employing both traditional racking-supported photovoltaic systems and innovative low-profile solutions [24]. Efforts have been made employing both ballast structures to support rigid solar panels and flexible thin-film solar technologies directly adhered to exposed surfaces [25].
Hybrid biogas–PV solar systems also have the potential to offer an alternative energy solution for rural communities [26]. Simulations and experimental studies demonstrate the feasibility of such hybrid systems, with PV components showing high performance ratios and biogas production yielding significant methane content [27]. In Mendoza, the implementation of a hybrid system achieved a reduction in emissions ranging from 44.1% to 70.5%, underscoring its significant contribution to mitigating climate change [28]. Various software tools have been developed for estimating and designing PV systems, providing capabilities to simulate and analyze both standalone and grid-connected PV systems [29,30]. The HelioScope software platform has been widely used to estimate PV system performance with acceptable accuracy [31,32,33]. There is a noticeable knowledge gap in developing countries regarding the effective integration of bioenergy generation through the AD of MSW. Similarly, there is a lack of research addressing how photovoltaic technology can utilize closed landfills to reduce the reliance on fossil fuels. Exploring these areas is crucial for the formulation of effective strategies aimed at addressing environmental and energy challenges in these contexts.
The joint adoption of bioenergy and photovoltaic solar technologies in closed landfills can align with the Sustainable Development Goals (SDGs), particularly in relation to affordable and clean energy (SDG 7) and climate action (SDG 13). However, it is essential to consider the technological and economic challenges that may arise, such as installation and maintenance costs and the need for specialized infrastructure to efficiently capture and utilize biogas. These considerations are crucial to ensure the viability and sustainability of the proposed solutions, thereby maximizing their positive impact in the context of developing countries.
The objective of this study, through a scenario analysis of landfill cells, is to evaluate the energy potential of a biogas–solar PV system in the Metropolitan Landfill of Chihuahua, Mexico. The findings are of significant relevance for decision-makers, as they provide crucial information regarding the energy production potential of the biogas–PV solar system in landfills. These results are expected to drive the efficient implementation of hybrid biogas–PV solar systems in landfills, promoting integrated solid waste management and contributing to the reduction in carbon emissions and other pollutants throughout their life cycle.

2. Materials and Methods

This study focuses on the Metropolitan Landfill of Chihuahua, located at Km 7.5 Carretera a Aldama, 31627 Chihuahua, Chih. (28°41′58.3″ N 106°02′16.0″ W), which has been in operation since 1993. The landfill receives and disposes of approximately 1250 tons of Municipal Solid Waste (MSW) daily, serving the municipalities of Chihuahua, Aldama, and Aquiles Serdán in the state of Chihuahua, Mexico. The Metropolitan Landfill consists of two cells, one of which was closed in 2005, while the other is expected to close in 2024 (Figure 1). Cell 1 operated for 23 years, while Cell 2 is expected to have an operational period of 10 years. It is important to note that during the operational periods of both cells, there was no formal separation process for the waste fractions in the MSW of Chihuahua. Only the activities of informal waste pickers were identified. This lack of technical separation may significantly influence the composition of the biogas generated.
The Metropolitan Landfill has an infrastructure that includes leachate management systems via manual recirculation and a biogas collection system consisting of 13 flare chimneys (flares) approximately 3 m deep, distributed unevenly across the cell. It lacks an explicit system for capturing and utilizing the methane generated; instead, the biogas is simply flared and/or released into the atmosphere. The site’s total capacity allows for significant waste storage, with accumulated disposal reaching critical levels in Cell 1, which is now closed. Cell 2, currently operational, was designed with technological improvements such as soil impermeabilization and drainage systems to minimize its environmental impact. However, the system lacks venting chimneys, resulting in a lack of data on the biogas produced. The site, with both cells, has played a key role in regional waste management, adapting to growing environmental and regulatory challenges.
Nevertheless, the Metropolitan Landfill has recently become a critical focus due to its proximity to the expanding urban population—just 500 m away—which, although compliant with Mexican regulations, raises concerns about potential health risks and nuisances associated with odors and fires. Additionally, there is a need to establish a new emergency cell, as Cell 2 nears saturation, to extend the site’s lifespan to its maximum. This emergency cell has been considered even though the opening of a new landfill in the Mapula area is planned, as the process has been halted due to opposition from the local population, creating uncertainty regarding the future management of MSW.
To estimate MSW generation, a mathematical model was employed based on population growth and the analysis of historical waste generation trends, projecting for a 20-year period. The average composition of MSW from the three economic strata across the three seasons of the year was obtained from a study conducted by Gómez et al. (2009), assuming that these values have remained constant during the analysis period [34]. For the characterization of biogas composition in the field, the Landtec BIOGAS 5000 probe was used, which employs electrochemical cells and infrared reflectance sensors to perform measurements in landfills [35]. This device allows for the measurement of methane (CH4) and carbon dioxide (CO2) concentrations as percentages, as well as hydrogen sulfide (H2S) concentrations in parts per million (ppm), with a maximum measurement capacity of 9999 ppm for the latter compound. For this study, the six flares indicated in Figure 1 were selected, as they were the ones producing the most biogas due to having less blockage in the venting system. In this study, two models were selected and applied to estimate the biogas production in the Metropolitan Landfill based on the available scientific literature: the LandGEM model and the MMB model.
The LandGEM model, developed by the United States Environmental Protection Agency (EPA), is a widely used tool for estimating emission rates at MSW disposal sites. This model quantifies emissions resulting from the decomposition of biodegradable waste using a first-order kinetic decomposition equation and default emission factors to estimate the potential for biogas generation. The emission factors depend on variables such as temperature, humidity, nutrient availability, pH, and the type and composition of the MSW [10,36]. LandGEM estimates emission rates for methane, carbon dioxide, volatile organic compounds, and other atmospheric pollutants.
For its application, parameters such as the average amount of MSW deposited, the year of landfill opening and closure, average precipitation, and methane content in the biogas were used, following the parameters proposed by the Clean Air Act. Emission factors were obtained from EPA inventories [15,37,38].
The MMB model is a regionalized version of LandGEM, specifically adapted to estimate biogas production in Mexican landfills. It considers a one-year period from the time the waste is placed until the start of biogas generation, followed by an exponential decline as the organic fraction is consumed. The model uses independent equations to calculate biogas generation for four groups of organic waste, categorized by their degradation index. Correction factors are applied to improve the estimation accuracy. In this study, the MMB complemented the LandGEM estimates by adjusting them to the specific conditions of the Metropolitan Landfill and Mexican regulations [39,40].
Simulation tools are essential for efficiently planning and designing a hybrid biogas–PV system at the Metropolitan Landfill, maximizing renewable energy generation and reducing reliance on conventional energy sources [41,42]. In this study, the HelioScope software was applied to simulate the performance of the photovoltaic system at the Metropolitan Landfill. By inputting local meteorological data and the site’s topographic characteristics, a detailed analysis of the expected system performance was conducted. Factors such as shading losses, electrical resistance, and soiling were considered. The HelioScope simulation estimated the optimal size of the photovoltaic system, accounting for the site’s capacity, energy demands, and specific solar generation conditions in the region.

3. Results and Discussion

3.1. Cell 1 of the Metropolitan Landfill

Table 1 below presents the results of the concentrations of biogas components detected in the biogas wells of Cell 1.
The biogas analysis indicated a methane concentration ranging from 43.1% to 53.9%, exceeding the minimum recommended threshold of 40% [28], as detailed in Table 1. Moreover, the detected H2S concentrations are considered low, as they typically range from 10 to 2000 ppm, although under specific conditions, they can reach levels as high as 10,000 ppm [43,44]. To ensure safe engine operation, the concentration of hydrogen sulfide should not exceed 200 ppm, with a preferred threshold of less than 50 ppm [45].

3.1.1. Biogas Estimation (Cell 1)

For Cell 1 of the Metropolitan Landfill, a capture efficiency of 63% was determined, considering that 50% of the waste area had a gas capture system and 80% of the area had final cover. Based on in situ observations, numerous biogas leaks were identified, particularly near the biogas wells, which led to an assumption of 50% capture system effectiveness. Using the MMB model and the described conditions, which are proposed to represent the state of Cell 1, the maximum biogas generation was determined to be 3776 m3/h, with 50% methane content. The estimated biogas recovery was 2373 m3/h, with 50% methane and a potential for generating up to 3.9 MW of electricity. Furthermore, it was estimated that CO2 equivalent emissions amounted to 7442 tons in 2017, the year of the highest production for this cell. The model projects that by 2025, biogas generation will be 2532 m3/h, with a potential recovery of 1595 m3/h and an electrical production of 2.6 MW, estimating a reduction in CO2 equivalent emissions of 105,046 tons.
Figure 2 presents a graph showing the projections for biogas generation and recovery under the aforementioned conditions for Cell 1 of the Metropolitan Landfill.
An additional scenario was analyzed for Cell 1, considering an increase in the waste coverage area to 80%, partially improving the cell’s coverage, which would require an investment beyond the scope of this study. Using the MMB model for this scenario, it was estimated that by 2025, approximately 7940 million cubic meters of methane emissions could be avoided annually, and the maximum electricity generation capacity was determined to reach 4.2 MW.
Using the LandGEM model, methane production was estimated at 28.72 million cubic meters in 2017, equivalent to 3278.5 m3/h. It is important to note that this model does not consider the percentage of final cover as a variable parameter. Additionally, the LandGEM model projects that by 2025, 2635.61 m3/h of methane could be utilized, while the MMB model estimated a methane production of 1266 m3/h for the same year.
Also, it is important to note that the results from the MMB model take into account a greater number of parameters to describe the behavior of the landfill, such as the occurrence of fires, the specific characterization of MSW in each state of the Mexican Republic, and elements of cell insulation. These considerations reduce the uncertainty of the predictions, making the MMB model the more appropriate choice for calculating the maximum electricity production capacity.
The concentration of benzene and toluene is influenced by municipal solid waste (MSW) management practices, especially when hazardous waste is disposed of alongside other waste types in the same cell. Various studies conducted by the research team have confirmed the presence of hazardous waste in landfills within the region, including items such as batteries, mercury thermometers, aerosols, ceramics, lamps, and pharmaceutical products. Associated with these findings, the results indicate a higher production of aromatic organic compounds like benzene and toluene when hazardous waste is co-disposed with other types of waste (Supplementary Material). According to the model, the potential emission from Cell 1 was estimated at 827.5 tons of non-methane organic compounds (NMOCs) per year, with toluene (a highly toxic volatile organic compound, VOC) being the most prevalent, projected to emit 37.59 tons in the year 2025.
These findings are consistent with other international studies that have identified toluene as the gas with the highest emission rate in this context [38]. The results emphasize the importance of considering the health impacts associated with MSW, particularly concerning the presence of VOCs and hazardous air pollutants.

3.1.2. Photovoltaic System in the Landfill Site (Cell 1)

It was determined that Cell 1 of the Metropolitan Landfill covers an approximate area of 196,852.79 m2, while Cell 2 spans an area of 144,414.24 m2. The simulation results indicated that, considering both cells, approximately 69,323 JA solar photovoltaic panels, model JAM6-72-300/SI of 300 W, could be installed, generating a total of 20.79 MW. However, to achieve the installation of this number of panels and attain high efficiency in photovoltaic energy capture, it is also necessary to condition and level the terrain, significantly increasing the base investment of the photovoltaic system, along with the additional preparations required to optimize the system.
Figure 3 presents a proposed layout for the placement of photovoltaic (PV) panels, taking into account the existing pathways in Cell 1 of the Metropolitan Landfill, as well as the addition of diagonal paths at the corners to improve mobility during maintenance activities. With this layout, it is estimated that a total of 50,061 photovoltaic panels could be installed, with a generation capacity of 15 MW. However, the upper right region of the array would not receive direct solar radiation, significantly reducing the efficiency of the panels in that specific area and affecting the overall performance of the photovoltaic system.
A proposed solution is to elevate the entire section of panels on the right side of Cell 1 with an adjustable structure. This structure would allow the solar panels to be oriented toward the south, thereby optimizing their performance. In this alternative scenario, it was calculated that a total of 32,625 photovoltaic modules could be installed, with a generation capacity of 9.79 MW (Figure 3). This reduction in the number of panels and power generated is a measure aimed at ensuring higher efficiency in the remaining areas and efficiently utilizing the available space and investment resources.

3.2. Cell 2 of the Metropolitan Landfill

3.2.1. Biogas Estimation (Cell 2)

The estimated biogas generation in Cell 2 of the Metropolitan Landfill was conducted considering a capture system efficiency of 80%. It was estimated that the cell would reach its maximum biogas generation rate, peaking at 2556 m3/h in the year 2025, which will be the first year after its closure. Based on this biogas generation, the maximum estimated electrical energy generation capacity for that year will be 3.4 MW, which corresponds to the utilization of 2045 m3/h of biogas. This process not only prevents the emission of 134,688 tons of CO2 equivalents during the same year, as illustrated in Figure 4, but also contributes to renewable energy production, supports waste-to-energy strategies, and aligns with global efforts to mitigate climate change by reducing the reliance on fossil fuels.
In this study, it was assumed that both Cell 1 and Cell 2 of the Metropolitan Landfill in Chihuahua have the same waste characterization, climate conditions, and annual deposition, which resulted in similar biogas generation estimates during the year of peak biogas production. However, Cell 1 operated for 23 years, whereas Cell 2 is expected to operate for 10 years. The similarity in results is attributed to the fact that Cell 1 has a final cover that does not meet isolation requirements, leading to a greater number of leaks and lower biogas recovery.
For Cell 2, an annual emission potential of 745.2 tons of NMOCs was estimated, with toluene (VOC) being the predominant compound, reaching 33.86 tons in the year 2025.
Due to the shorter operational period of Cell 2 and the amount of waste deposited, a notable difference in biogas generation was identified between the two cells. Cell 1 accumulated a total of 8,475,000 metric tons of waste, while Cell 2 accumulated 4,057,200 metric tons. This difference in the mass of degradable waste directly influences the biogas generation capacity of each cell, which aligns with estimates from other landfills in relation to the amount of waste they receive.

3.2.2. Photovoltaic System in the Landfill Site (Cell 2)

In the proposed design for the photovoltaic panel arrangement in Cell 2 (Figure 5), the existing access roads were considered, along with the addition of diagonal roads to improve accessibility and logistics. It was determined that it would be feasible to install a total of 42,114 photovoltaic modules, with an electrical generation capacity of 12.6 MW. Figure 5 presents an additional alternative, where it is proposed to eliminate the solar panels on the right side of Cell 2, resulting in a reduction in the number of modules to 32,305 and an electrical capacity of 9.69 MW. This freed area could be used for the implementation of vegetation cover and also offers potential for the installation of biogas extraction pipes, along with the possibility of establishing a station for monitoring and controlling biogas quality for future use.
It was estimated that the installation of the biogas–solar PV system in Cell 1 of the Metropolitan Landfill could generate between 12.39 MW and 13.99 MW, depending on the quality of the cell’s covering system. For Cell 2, an estimated generation of 13.09 MW was determined. Therefore, a total potential of up to 27.08 MW for the biogas–solar PV system is projected for 2025, utilizing both cells that make up the Metropolitan Landfill.
It is important to note that, in order to utilize the biogas in the Metropolitan Landfill cells, adjustments such as deeper chimney drilling will be required. This process carries a significant risk of generating leaks in the system, which could compromise biogas capture efficiency and increase fugitive emissions.
For a sanitary seal to be suitable for use in landfills, it must have low porosity and minimal water absorption. A synthetic seal of at least 2 mm and a mineral seal with 0.25 m of bentonite sand and 0.50 m of clay are recommended [46]. Natural clays such as bentonite, geomembranes (Geosynthetic Clay Liner/GCL), and mixtures of both are frequently used due to their low hydraulic conductivity (<10−9 m/s) and contaminant retention capacity [47,48]. GCLs, consisting of bentonite sandwiched between two geotextiles, represent an efficient alternative to compacted clay covers due to their easy installation and limited thickness [49]. Mixtures of bentonite–fly ash and bentonite–sand have been studied for landfill liners [50]. Although these materials can be costly in low-resource countries, the addition of residual chamotte improves impermeability. In developing countries, compacted clay liners (CCLs) are common due to their low cost and the use of local materials. The use of recycled zeolite as an additive in CCLs improves sealing capabilities and mitigates environmental and social impacts [51]. Zeolite embedded in bentonite (BEZ) is effective due to its high cation exchange capacity and low hydraulic conductivity [52]. Zeolites, with their microporous structure and high pozzolanicity, enhance compaction and act as filters for leachates [53]. In Mexico, the availability of high-quality zeolites [54] reduces the cost of implementing BEZ as landfill liners.
Using the LandGEM model, a production of 25 million cubic meters of methane was estimated for 2024, with a capture efficiency of 80%, and considering that 90% of the waste area has final cover. A production of 18 million cubic meters of methane was determined for 2024, which represents more than double the amount calculated using the MMB model. In addition, it is crucial to consider that during the implementation of photovoltaic parks in landfills, welding and spark generation are strictly prohibited due to the presence of fugitive biogas emissions. In systems with approximately 50% methane content, these emissions pose significant flammability risks.
The strength of this study lies in its comprehensive evaluation of a hybrid biogas–solar PV system for landfill energy recovery, combining advanced predictive modeling with practical implementation strategies to address both energy generation and environmental sustainability challenges in developing countries.

4. Conclusions

  • This study demonstrates that biogas is a viable and sustainable source of clean energy, with generation projections varying between the LandGEM and MMB models, highlighting its potential for energy recovery and utilization.
  • The integration of hybrid biogas–solar PV systems in landfills enhances waste management efficiency and renewable energy generation, fostering innovation in the energy sector and promoting sustainable practices. Such systems also generate employment opportunities in waste management and renewable energy industries, emphasizing their socioeconomic benefits.
  • Mathematical models and simulation tools are essential resources for the planning, design, and optimization of hybrid biogas–solar PV systems. These tools support the maximization of renewable energy output and reduce the dependence on conventional energy sources, aligning with global renewable energy transition goals.
  • The implementation of advanced waste separation and recovery techniques, supported by robust recycling infrastructures and sustainable markets for recycled products, is critical for comprehensive urban waste management.
  • Enhanced final cover systems significantly reduce fugitive emissions and improve biogas production efficiency. The quality of these covers and the selection of suitable materials play a pivotal role in optimizing the performance of biogas capture systems.
  • Feasibility studies for the certification of carbon credits generated through biogas utilization are recommended. These certifications offer potential economic benefits, mitigate greenhouse gas emissions, and contribute to improved air quality and public health.
  • Partial closures of landfill cells, combined with the installation of gas flares or biogas burners, are necessary to reduce fire risks, enhance biogas collection, and prevent emissions into the atmosphere. Implementing a leveling plan to avoid terrain depressions is critical for the efficient installation of solar panels, reducing additional preparation costs and ensuring optimal energy generation.
  • Comparative assessments of polycrystalline silicon and thin-film solar panels reveal that thin-film panels require minimal land preparation and offer a cost-effective balance between energy production and installation requirements.
  • Long-term studies on the economic and operational feasibility of hybrid biogas–solar PV systems are essential to guide effective implementation strategies. The findings emphasize the critical role of integrating biogas and solar PV technologies within landfill operations to advance sustainable energy solutions and enhance urban resilience. Incorporating these technologies into urban policies and regulatory frameworks has the potential to deliver significant environmental, economic, and social benefits. Furthermore, policy interventions should prioritize financial incentives such as subsidies, tax reductions, and streamlined permitting processes to facilitate widespread adoption. Establishing mandatory waste-to-energy targets and integrating renewable energy credits within carbon trading systems could further support the transition to sustainable urban waste management, fostering innovation and reducing dependence on conventional energy sources.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/urbansci9010017/s1, Figure S1: VOC emissions in Cell 1; Table S1: Gas and emission rates in Cell 1; Figure S2: VOC emissions in Cell 2; Table S2: Gas and emission rates in Cell 2.

Author Contributions

Conceptualization, H.A.L.-A. and C.L.M.; methodology, G.K.P. and H.A.L.-A.; software, L.A.L.M.; validation, H.A.M.R., O.C.A. and H.A.M.R.; formal analysis, H.A.L.-A. and A.P.-H.; investigation, H.A.L.-A. and G.K.P.; resources, C.L.M.; data curation, H.A.L.-A. and G.K.P.; writing—original draft preparation, H.A.L.-A.; writing—review and editing, A.P.-H., L.A.L.M., O.C.A., H.A.M.R. and H.A.L.-A.; visualization, L.A.L.M.; supervision, H.A.L.-A. and A.P.-H.; project administration, C.L.M. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

Data is contained within the article or Supplementary Material.

Acknowledgments

We gratefully acknowledge the Centro de Investigación en Materiales Avanzados S. C. (CIMAV) and Universidad La Salle de Chihuahua, as well as the projects CONAHCYT-SENER 243715, CONAHCYT-SEMAR 305292, and CONAHCYT-CIENCIA DE FRONTERA 2023_G_1566 for their support in the generation of infrastructure and laboratories.

Conflicts of Interest

The authors declare no conflicts of interest.

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Urbansci 09 00017 g001
Figure 1. Metropolitan Landfill of Chihuahua (28°41′58.3″ N 106°02′16.0″ W) and biogas sampling points [own research].
Figure 1. Metropolitan Landfill of Chihuahua (28°41′58.3″ N 106°02′16.0″ W) and biogas sampling points [own research].
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Figure 2. Projections of biogas (methane 50% in m3/h) generation (solid line) and recovery (dotted line) in Cell 1 of the Metropolitan Landfill calculated using the MMB [own research].
Figure 2. Projections of biogas (methane 50% in m3/h) generation (solid line) and recovery (dotted line) in Cell 1 of the Metropolitan Landfill calculated using the MMB [own research].
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Figure 3. Proposed system for the photovoltaic system in Cell 1 [own research].
Figure 3. Proposed system for the photovoltaic system in Cell 1 [own research].
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Figure 4. Projections of biogas (methane 50% in m3/h) generation (solid line) and recovery (dotted line) in Cell 2 of the Metropolitan Landfill calculated using the MMB [own research].
Figure 4. Projections of biogas (methane 50% in m3/h) generation (solid line) and recovery (dotted line) in Cell 2 of the Metropolitan Landfill calculated using the MMB [own research].
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Figure 5. Proposed system for the photovoltaic system in Cell 2 [own research].
Figure 5. Proposed system for the photovoltaic system in Cell 2 [own research].
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Table 1. Results of the field characterization of biogas [own research].
Table 1. Results of the field characterization of biogas [own research].
WELLCH4 (%)
MEASURE (M#)		CO2 (%)
MEASURE		H2S (ppm)
MEASURE
M1M2M3M4M5M6M1M2M3M4M5M6M1M2M3M4M5M6
1 53.652.153.451.952 43.144.144.143.443.7 4731566960
65253.051.652.352.252.842.743.843.14342.943.3123491188
750.951.850.551.450.751.543.744.343.743.643.543.912431216713
852.751.953.753.54854.143.34343.643.540.743.6131981428
934.152.250.647.553.645.431.740.840.939.443.536.57834112
1352.3353.252.553.953.153.840.842.341.541.541.441.5233817262021
Measure (d/m/y): M1 05/08/22; M2 26/08/22; M3 15/09/22; M4 19/09/22; M5 23/09/22; M6 26/09/22.
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López-Aguilar, H.A.; Kennedy Puentes, G.; Lozoya Márquez, L.A.; Chávez Acosta, O.; Monreal Romero, H.A.; López Meléndez, C.; Pérez-Hernández, A. Evaluation of Energy Potential in a Landfill Through the Integration of a Biogas–Solar Photovoltaic System. Urban Sci. 2025, 9, 17. https://doi.org/10.3390/urbansci9010017

AMA Style

López-Aguilar HA, Kennedy Puentes G, Lozoya Márquez LA, Chávez Acosta O, Monreal Romero HA, López Meléndez C, Pérez-Hernández A. Evaluation of Energy Potential in a Landfill Through the Integration of a Biogas–Solar Photovoltaic System. Urban Science. 2025; 9(1):17. https://doi.org/10.3390/urbansci9010017

Chicago/Turabian Style

López-Aguilar, Héctor Alfredo, Guadalupe Kennedy Puentes, Luis Armando Lozoya Márquez, Oscar Chávez Acosta, Humberto Alejandro Monreal Romero, Claudia López Meléndez, and Antonino Pérez-Hernández. 2025. "Evaluation of Energy Potential in a Landfill Through the Integration of a Biogas–Solar Photovoltaic System" Urban Science 9, no. 1: 17. https://doi.org/10.3390/urbansci9010017

APA Style

López-Aguilar, H. A., Kennedy Puentes, G., Lozoya Márquez, L. A., Chávez Acosta, O., Monreal Romero, H. A., López Meléndez, C., & Pérez-Hernández, A. (2025). Evaluation of Energy Potential in a Landfill Through the Integration of a Biogas–Solar Photovoltaic System. Urban Science, 9(1), 17. https://doi.org/10.3390/urbansci9010017

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