Compressed Biogas: A Clean Energy Solution

26th October 2023

In pursuing sustainable energy solutions and reducing carbon emissions, the focus on renewable and alternative fuels has gained significant momentum. Compressed Biogas (CBG) has emerged as a promising biofuel, providing a cleaner and more sustainable alternative to traditional fossil fuels. Compressed air, a versatile and widely used medium, is pivotal in various processes within biogas plants.

Applications of Compressed Air in Biogas Plants

Biogas Collection and Pressurisation: Compressed air plays a vital role in the initial stages of the biogas production process. Biogas generated through anaerobic digestion is often released in anaerobic digesters, where it can be mixed with compressed air to facilitate the collection and conveyance of the gas to downstream processing units. Additionally, compressed air is used to pressurize the Biogas, making it easier to handle and transport.

Biogas Upgrading: The impurities present in biogas, including carbon dioxide and moisture, must be removed to meet the specifications required for biogas. Compressed air-driven processes like pressure swing adsorption (PSA) and water scrubbing are used for biogas upgrading. In PSA, compressed air alternately pressurises and depressurises adsorbent beds, allowing selective carbon dioxide adsorption, resulting in a cleaner and more methane-rich gas suitable for conversion to biogas.

Pneumatic Conveying: In biogas plants, organic waste materials are transported between different process stages. Compressed air-based pneumatic conveying systems are used to transport solid feedstock, slurry, and digestate—the residue left after anaerobic digestion. These systems ensure efficient and controlled movement of materials, minimizing manual handling and optimizing plant operations.

Gas Compression for Storage and Distribution: Once upgraded to biogas, the gas must be stored and distributed efficiently. High-pressure systems are employed to increase the pressure of biogas, enabling its storage in high-pressure containers or pipelines. This pressurization ensures a higher energy density, making transportation and utilization of biogas more viable.

Vehicle Fuelling Stations: Biogas is gaining traction as a sustainable transportation fuel. Compressed air is used in the operation of vehicle fuelling stations, where biogas is dispensed to compressed natural gas (CNG)-powered vehicles. High-pressure compressors feed the accurate and safe fuelling of vehicles.

Maintenance and Cleaning: Biogas production plants require regular maintenance to ensure optimal performance and longevity of equipment. Compressed air is used for cleaning, effectively removing dust, debris, and accumulated residues from equipment, pipelines, and storage tanks. This aids in maintaining the efficiency and integrity of the entire production process.

Benefits of Compressed Air in Biogas Plants

The utilization of compressed air in biogas plants offers several benefits that contribute to the overall efficiency, safety, and environmental sustainability of the process:

Efficient Transportation: Compressed air-based pneumatic conveying systems enable the smooth movement of feedstock and by-products, reducing the need for manual handling and improving operational efficiency.

Effective Upgrading: Compressed air-driven biogas upgrading processes like PSA ensure the removal of impurities, resulting in high-quality biogas that meets industry standards.

Optimised Storage: Gas compression enhances the energy density of biogas, enabling efficient storage and distribution.

Safe Operation: Compressed air-driven safety systems prevent air entry into gas storage tanks, reducing the risk of explosions and ensuring safe plant operation.

Cleaner Fuelling: Compressed air-powered fuelling stations ensure accurate and controlled dispensing of bio-CNG to vehicles, promoting cleaner and more efficient transportation.

Compressed Biogas (CBG) holds tremendous potential as a sustainable and renewable energy source, contributing to reducing greenhouse gas emissions and dependence on fossil fuels. Compressed air's versatile applications within biogas plants are instrumental in the entire production cycle, from biogas collection to vehicle fuelling. Compressed air plays a pivotal role in ensuring the viability and effectiveness of biogas as a clean and environmentally friendly alternative to conventional fuels by aiding in biogas collection, upgrading, storage, and distribution. As the world continues to embrace cleaner energy solutions, the collaboration between compressed air technology and biogas production remains at the forefront of the sustainable energy revolution.

- Satish Kini, CEO, Elgi Sauer Compressors Ltd.