Bioenergy is considered one of the most reliable and flexible forms of renewable energy, primarily due to its environmental and economic benefits. Among the most promising types of bioenergy are biogas and biomethane – renewable fuels produced from locally available, biodegradable resources, including residues from agriculture, livestock farming, food production, and various industrial sectors.

Biogas and biomethane systems contribute to the goals of the circular economy and play a key role in the European Union’s ambition to become climate-neutral by 2050, as outlined in the European Green Deal. The European Union has already committed to producing 35 billion cubic meters of biomethane annually by 2030 under the REPowerEU plan and achieving these goals will require coordinated efforts in several areas.

Technological Advancements in Biogas Systems

Biodegradable materials can be converted into biogas and biomethane through various biological or thermochemical processes. Anaerobic digestion is a biological process in which microorganisms break down organic matter in the absence of oxygen, while thermochemical gasification converts biomass into syngas using high temperatures and controlled amounts of oxygen or steam.

Innovative technologies are opening the door to more modular, flexible, and efficient biogas systems, which are easier to integrate into smart, sustainable energy networks. Each technology, however, presents different advantages and trade-offs in terms of capital costs, operating expenses, energy use, methane yield, and environmental impact.

Although raw biogas is already useful and can be used as an energy source, it cannot be directly injected into the gas grid or utilized as vehicle fuel without undergoing treatment. The initial step, biogas cleaning, is essential for most applications and typically involves energy-demanding processes to remove contaminants. This is followed by a second treatment known as biogas upgrading, which enhances the fuel quality by increasing its calorific value. Advanced technologies such as membrane separation, pressure swing adsorption, chemical scrubbing, and emerging biological techniques are employed in this phase to eliminate CO₂ and other impurities. Water scrubbing, amine scrubbing, and membrane separation remain the most widely used and commercially mature options.

Biogas can be used directly to produce electricity and heat, particularly in combined heat and power (CHP) units or it can be upgraded to biomethane by removing CO₂, hydrogen sulfide, water vapor, and other impurities. Biomethane, containing over 95% methane, has chemical and physical properties comparable to fossil natural gas, but with a significantly reduced carbon footprint. It can be injected into natural gas distribution networks as renewable natural gas or used as a transport fuel in compressed (bio-CNG) or liquefied (bio-LNG) form, contributing to the decarbonization of the mobility sector.

Evaluating and optimizing biogas and biomethane systems

The approach for evaluating and optimizing biogas and biomethane systems includes several steps (illustrated in Figure 1). The initial phase focuses on identifying and selecting the core production technologies, including anaerobic digesters, gas cleaning and upgrading systems, and methanation units. These technological components are assessed in terms of their material balances and process efficiencies, which provide data on input-output relationships, energy yields, and waste streams. Additionally, this step involves identifying potential revenue streams and financial incentives, which are key drivers for economic feasibility.

Next phase includes defining scenario boundaries, encompassing both internal (system configuration, technology scale) and external (regulatory, market) conditions. A base case scenario is established, serving as the reference point, along with extreme case scenarios to explore variability and uncertainty. These scenarios support the analysis of material flows, including feedstocks, intermediate and final products, and process losses. They also enable a preliminary economic analysis (economic feasibility), estimating capital expenditures (CAPEX), operational expenditures (OPEX), and levelized costs for different technology pathways.

The other stage clarifies the purpose of the analysis, identifies the target audience, and defines the functional unit. To ensure that biogas technologies are not only technically viable but also economically and environmentally sustainable, two key evaluation tools are used: Techno-Economic Assessment (TEA) and Life Cycle Assessment (LCA). TEA evaluates the financial feasibility of biogas and biomethane projects and LCA, on the other hand, provides an overall picture of environmental performance, from raw material collection through gas production and end-use. However, both TEA and LCA outcomes depend on multiple factors, including the type of feedstock, methane leakage rates, plant efficiency, and the local regulatory and market environment. Based on this, a life cycle inventory (LCI) is compiled, capturing all relevant material and energy flows from construction to decommissioning, including emissions (direct, indirect, and avoided) and waste disposal. The LCI provides the foundation for both environmental impact assessment and cost modeling, allowing for an evaluation of system sustainability.

The final phase is the impact assessment, which synthesizes environmental and financial performance to validate the system and identify optimal configurations, while this step supports the direct application of results in several areas, such as policy development, strategic planning, marketing, and product innovation.

The Challenges and the Way Forward

On a global scale, biogas and biomethane remain underexploited compared to renewable sources like wind and solar energy. However, a key advantage of biogas lies in its ability to produce energy continuously, independent of weather conditions. Biogas production is climate-independence (in comparison to solar radiation and wind availability), which makes biogas a highly reliable and climate-resilient renewable energy source.

The future of biogas and biomethane will be shaped not only by technological advancements but also by the policy environment and market incentives that support wider deployment. The seasonal feedstock availability and upfront investment costs remain a significant barrier, particularly for small- and medium-scale plants in rural or economically disadvantaged areas. Moreover, regulatory harmonization is also critical. Inconsistent frameworks for grid injection, biomethane certification, and carbon accounting across countries can delay investments and limit cross-border trade in renewable gases. Transparent green gas guarantees of origin, along with streamlined permitting and subsidies, can accelerate deployment and build market confidence.

Through targeted investments in infrastructure (such as gas grid upgrades, bio-CNG and bio-LNG refueling stations, decentralized production facilities, data-driven monitoring systems), combined with the integration of advanced digital tools (including artificial intelligence for operational optimization, blockchain for biomethane certification, remote sensing for feedstock monitoring), biogas and biomethane have the potential to become foundational elements of Europe’s transition to a circular and carbon-neutral bioeconomy.

Biogas plants rely on proven biomass conversion technologies that allow for steady and predictable energy generation. Biogas, as well as biomethane, can be stored and utilized on demand, offering a level of flexibility and other advantages over solar and wind systems. When supported by technological innovation, workforce training, public engagement, and the mix of policy support and stakeholder collaboration, these renewable gases can play a vital role in shaping the resilient and sustainable energy systems of the future.

Figure 1: The methodological approach for assessing and optimizing biogas systems, divided into 4 main steps:
(1) System and product development, (2) Scenario development, (3) Life cycle assessment and costing, and (4) Optimal scenario identification (Swinbourn et al., 2024).

References
Swinbourn, R., Li, C., Wang, F. (2024). A Comprehensive Review on Biomethane Production from Biogas Separation and its Techno-Economic Assessments. ChemSusChem, 17, e202400779. https://doi.org/10.1002/cssc.202400779

Sher, F., Smječanín, N., Hrnjić, H., et al. (2024). Emerging technologies for biogas production: A critical review on recent progress, challenges and future perspectives. Process Safety and Environmental Protection, 188, 834–859. https://doi.org/10.1016/j.psep.2024.05.138

Pavičić, J., Novak Mavar, K., Brkić, V., et al. (2022). Biogas and Biomethane Production and Usage: Technology Development, Advantages and Challenges in Europe. Energies, 15(8), 2940. https://doi.org/10.3390/en15082940

Mignogna, D., Ceci, P., Cafaro, C., et al. (2023). Production of Biogas and Biomethane as Renewable Energy Sources: A Review. Applied Sciences, 13(18), 10219. https://doi.org/10.3390/app131810219

Adnan, A. I., Ong, M. Y., Nomanbhay, S., et al. (2019). Technologies for Biogas Upgrading to Biomethane: A Review. Bioengineering, 6(4), 92. https://doi.org/10.3390/bioengineering6040092