Real-Time Biogas Monitoring Using Gas Sensors

Abstract

Biogas digesters are sustainable solutions for managing organic waste, but most monitoring systems focus mainly on methane and ignore toxic gases produced during anaerobic digestion. This proposed system introduces a low-cost multi-gas monitoring framework that detects both combustible and harmful gases in real time using sensor-based microcontroller technology. The system enables early detection of toxic gas buildup, improves worker safety, and helps optimise the digestion process. By using affordable and easily available sensors, the system supports safer, more efficient, and environmentally friendly biogas production while allowing users to take early preventive actions.

Introduction

The study focuses on developing a real-time gas monitoring system for biogas digesters using an ESP32-WROOM-32 microcontroller integrated with MQ-4 (methane) and MQ-135 (carbon dioxide) sensors. Biogas digesters convert organic waste into methane-rich gas via anaerobic digestion, producing both combustible and potentially harmful gases. Continuous monitoring is essential to ensure safety, maintain gas quality, and improve energy efficiency.

System Design:

1. Digester Setup:

   • Organic slurry (cow dung, vegetable waste, or other biodegradable materials) is loaded into a sealed digester.

   • Anaerobic microbes decompose the material over 5–7 days, generating biogas and nutrient-rich digested slurry.

2. Sensor Integration:

   • MQ-4 detects methane for fuel quality assessment.

   • MQ-135 detects CO? to prevent health risks and monitor digester efficiency.

   • Both sensors provide analog outputs to the ESP32 microcontroller for processing.

3. Microcontroller & IoT Platform:

   • The ESP32 processes sensor data, enabling real-time monitoring and data transmission.

   • The Blynk Web Dashboard displays gas concentration remotely, providing a user-friendly interface without complex server or app setup.

4. Safety and Efficiency:

   • Continuous monitoring reduces exposure to toxic gases, prevents engine corrosion, and ensures optimal methane content for energy production.

   • The system is compact, affordable, and suitable for small to medium biogas plants.

Conclusion

The current work has been able to illustrate how a multi-gas monitoring system can be designed by a low-cost ESP32-based microcontroller and implemented in anaerobic biogas digesters. The proposed system is also a better alternative to the traditional methods of monitoring since it can identify both the generation of energy and safety, unlike the traditional method that is principally oriented on methane production. The results of the experiments indicated that it was possible to ascertain the presence of gas in the digester with a high degree of certainty, starting with a zero-gas state and onward to quantifiable levels of methane and CO 2 as decomposition took place. This does not only confirm the adequate operation of sensing hardware but the overall monitoring scheme is also effective in real digestion scenarios. The proposed solution to the implementation of continuous real time monitoring consists of the integration of MQ-series gas sensors with the ESP32 microcontroller and wireless dashboard, which is practical and easy to use. This kind of accessibility is especially useful with small-scale and rural biogas installations where costly analytical equipment is not an option. The system enhances the safety of the workers by allowing them to detect the harmful or excessive gases in time, offering them an opportunity to control the digester better, and ensuring the efficient production of bio-gas. The constant and unique sensor responses are also an indication that the system can be applied to measure the performance of digestion and fuel quality in a significant manner. To sum up, the monitoring system developed presents a cost-effective, efficient, and the green-friendly solution to the contemporary biogas facilities. Through the integration of safety consciousness and the use of renewable energy surveillance, this piece of work has been put into contribution of more sustainable and well-managed biogas production systems. This can be enhanced in future with the addition of gas sensing, field deployment and the mechanism of automatic control to ensure further enhancements in the efficiency of the operation and environmental safety.

References

[1] Suruchi Dedgaonkar, Ankita Mohire, Ajinkya Jadhav, Sonali Pawar, Rushikesh Bane (2016). Biogas Monitoring System for Measuring Volume using Microcontroller & GSM. International Journal of Current Engineering and Technology. [2] Wassima Ait Ahmed, Mohammed Aggour, Fayçal Bennani (2015). Smart System for Bio Digester Monitoring. IEEE International Conference. [3] Andrea Pérez-Vidal, Leonardo Antonio Bermeo Varón, Lina Mariana Rodríguez-Jiménez, Sonia María Bolaños-Muñoz, Yordy Mario Lemos-Valencia, Jorge Antonio Silva-Leal, Patricia Torres-Lozada (2025). Development of a Continuous Biogas Pressure Measurement Device with Applications in Batch Anaerobic Digestion Tests. ACS Omega. [4] Ziyu Liu, Edvard Nordlander, Jose Chilo, Shoaib Amin (2013). Automatic Control for a Gas System Using a PIC Microcontroller. Bachelor\'s Thesis, Mälardalen University. [5] Lilik Sutiarso, Arief Abdurrakhman, Makhmudun Ainuri, Mirwan Ushada (2023). Simulation and Experimental Validation of Energy Management System Models for Electric Generators with Biogas Fuel from Agricultural Waste Using the PID Controller Method. Preprint (SSRN). [6] Karthik Rajendran, Solmaz Aslanzadeh, Mohammad J. Taherzadeh (2012). Household Biogas Digesters—A Review. Energies Journal. [7] Liang Yong, Zhou Zheng, Lu Wei, Cui Qi (2019). Improved Design of Biogas Engineering Alarm Based on STM32. International Conference on Information and Communications Technology (ICIIP). [8] Panupon Trairat, Sakda Somkun, Tanakorn Kaewchum, Tawat Suriwong, Pisit Maneechot, Teerapon Panpho, Wikarn Wansungnern, Sathit Banthuek, Bongkot Prasit, Tanongkiat Kiatsiriroat (2023). Grid Integration of Livestock Biogas Using Self-Excited Induction Generator and Spark-Ignition Engine. Energies Journal. [9] Julie Jimenez (2015). Instrumentation and Control of Anaerobic Digestion Processes. Reviews in Environmental Science and Biotechnology. [10] Kanokwan Boe (2006). Online Monitoring and Control of the Biogas Process. Ph.D. Thesis, Technical University of Denmark. [11] Xinshan Qi, Shuping Zhanga, Yuzhi Wanga, Renqing Wanga (2019). Advantages of the Integrated Pig-Biogas-Vegetable Greenhouse System. Research Publication. [12] LOGARASU R., and team members (2025). SMART IoT-Based Biogas Monitoring System. Conference Publication. [13] Wei Shuyi, and co-authors (2023). The Temperature and Pressure Remote Intelligent Control System. Technical Report. [14] Hendrik Elvian Prasetya, and colleagues (2023). Smart Biogas Plant Monitoring System Using Internet of Things. Journal Publication. [15] Hongbing Liu (2021). The Design of Automatic Material Storage. Technical Report. [16] Samaa Fawzy, Mohammed Saeed, Abdelfattah Eladl, Magdi El-Saadawi (2020). Adaptive Control System for Biogas Power Plant Using Model Predictive Control. Journal of Modern Power Systems and Clean Energy. [17] Ennio R. Piceno-Diaz (2022). Robust Nonlinear Model Predictive Control for Two-Stage Anaerobic Digestion. Technical Publication. [18] D. Ajay Abilash, P. Kayalvizhi, R. Rakesh, S. Balamurugan (2016). Automation in Biomethanation Plant Using PLC and SCADA. International Journal of Bio-Science and Bio-Technology. [19] KeChrist Obileke, Edson L. Meyer, Sampson Mamphweli, Golden Makaka (2024). Design and Evaluation of a Gas Concentration Measurement and Monitoring Device. Scientific Reports. [20] Kanokwan Boe, Irini Angelidaki (2010). Implementation of an Online Volatile Fatty Acids Sensor for Biogas Process Control. ForskEL Project Report, DTU. [21] Ali Moradvandi, Sjoerd Heegstra, and team (2025). Model Predictive Control of Feed Rate for Stabilising and Enhancing Biogas Production. Journal of Process Control. [22] Taeyoung Kima, Junyeong Anc, Jae Kyung Jangd, In Seop Changa (2021). Determination of Optimum Electrical Connection Parameters. Technical Report. [23] Peijie Huo, Fang Yang, Hongbo Luo, Mingkuan Zhou, Yanlin Zhang (2021). Distributed Monitoring System for Precision Management of Household Biogas Plants. Technical Publication. [24] Bernhard Drosg (2013). Process Monitoring in biogas plants. Research Publication. [25] Iswanto, Alfian Ma’arif, Bilah Kebenaran, Prisma Megantoro (2022). Design of Gas Concentration Measurement System. Technical Report. [26] Kazuto Yoshida, Naoto Shimizu (2020). Biogas Production Management Systems with Model Predictive Control. Research Publication. [27] Z. Recebli, S. Selimli, M. Ozkaymak, O. Gonc (2015). BIOGAS PRODUCTION FROM ANIMAL MANURE. Journal of Engineering Science and Technology. [28] Prithiviraj C., Mondal B., Sivarethinamohan R., Senthil Kumar M. (2023). Optimisation of pilot-scale biogas plant for mixed food wastes with cow dung by anaerobic digestion process. Global NEST Journal. [29] Shwetal Ramesh Bantey (2024). PRODUCTION OF BIOGAS USING KITCHEN WASTE. INTERNATIONAL JOURNAL OF CREATIVE RESEARCH THOUGHTS (IJCRT). [30] Tanko Bako, Larry Orobome Agberegha, Abubakar Said Aliyu (2022). Development of a mini biogas digester for household use. Discovery. [31] Lucy F. R. Montgomery, Günther Bochmann (2014). Pretreatment of feedstock for enhanced biogas production. IEA Bioenergy (Technical Brochure). [32] Günther Bochmann, Lucy F. R. Montgomery (2013). Storage and pre-treatment of substrates for biogas production. The Biogas Handbook (Woodhead Publishing Limited). [33] Hemant Thakur, Atul Dhar, Satvasheel Powar (2022). Biogas production from anaerobic co-digestion of sewage sludge and food waste in a continuously stirred tank reactor. Results in Engineering. [34] S. Abanades, H. Abbaspour, A. Ahmadi, B. Das, M. A. Ehyaei, F. Esmaeilion, M. El Haj Assad, T. Hajilounezhad, D. H. Jamali, A. Hmida, H. A. Ozgoli, S. Safari, M. Al-Shabi, E. H. BaniHani (2022). A critical review of biogas production and usage with the legislations framework across the globe. International Journal of Environmental Science and Technology. [35] Pradyumna Kumar Champati, Chitrabhanu Sahoo (2024). IMPROVED EFFICIENCY OF A NEW BIOGAS PROTOTYPE MADE FROM SOLID KITCHEN WASTE. International Research Journal of Modernisation in Engineering Technology and Science.

Copyright

Copyright © 2026 Kamal R Krishna, Dr. K. G. Padmasine, Bharathi P. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.