The costs of biogas production can be categorised as follows: investment costs (depreciation costs), feedstock costs, staff costs, maintenance costs, and other running costs.

Feedstock costs: If wastes are used as a feedstock, a charge—a gate fee, for example—is usually levied for treating the wastes, thus producing revenue. While industrial residues and by-products can be very cheap to use as feedstocks, other products, like fermented energy crops, can be very costly. There is thus a wide range of possible feedstock costs, and these are highly dependent on the specific biogas project and the national boundary conditions. Investment costs: Investment costs (depreciation costs) including peripheral equipment and installations make up a large share of biogas plant costs. The investment costs of a biogas plant naturally depend on its size (capacity and throughput). Biogas installations follow economies of scale, meaning that as the capacity of a plant increases, the specific investment costs decrease. Plant capacities are, however, limited by available substrates and infrastructure; this means that the lower specific costs associated with larger-scale plants are sometimes not achievable.

Investment costs: Investment costs (depreciation costs) including peripheral equipment and installations make up a large share of biogas plant costs. The investment costs of a biogas plant naturally depend on its size (capacity and throughput). Biogas installations follow economies of scale, meaning that as the capacity of a plant increases, the specific investment costs decrease. Plant capacities are, however, limited by available substrates and infrastructure; this means that the lower specific costs associated with larger-scale plants are sometimes not achievable.

Moreover, some investment costs are feedstock-dependent. Biogas plants for the treatment of municipal wastes are more expensive because they have large closed halls (e.g., with low pressure to reduce smells). These halls are used for the handling and pre-treatment of feedstocks, with impurities (packaging, plastics, metal, etc.) being separated from the organic matter. Investment costs for energy crop digesters or industrial wastewater treatment reactors are often lower, as they need fewer peripheral installations. Another substantial part of the costs can be the biogas utilisation. From an investment perspective, direct heat utilisation is the cheapest solution. In industrial settings the biogas produced can often be co-fired in gas burners, with no or limited adaptation needed. More sophisticated gas utilisation concepts (e.g., combined heat and power production, upgrading to biomethane, fuel cells) result in higher investment costs.

Staff costs: Today, state-of-the-art biogas plants are well automated, resulting in fairly low staff costs; however, extensive feedstock pre- treatment—as occurs with the organic fraction of municipal solid waste or packaged food waste—can increase the demand for human labour.
In general, biogas technology, and in particular the microbial degradation process, is rather complex; it is thus clearly advantageous to have well-trained staff to guarantee a stable, reliable operation.

Digestate logistics costs: The digestate produced can generate considerable costs, depending on the size of the installation and how integrated it is into local organic fertiliser utilisation. The most common digestate utilisation is land application as fertiliser, but this is limited because there may not be farmland nearby and/or because of environmental legislation (e.g., the EU Nitrate Directive). This means that in very large-scale biogas installations, the digestate land application can become a bottleneck because the transport distances to agricultural land where the digestate can be applied increases with the size of the installation, and so too do the transportation and application costs. In small-scale biogas plants–especially in an agricultural setting–the digestate application as a fertiliser on the land is often not a problem. Large digestate storage facilities are typically needed, as land application can be prohibited during winter, the agricultural soils cannot effectively take up nutrients and digestate must be stored.

Other costs: These are costs for maintenance of the machinery, property, insurance, administration, etc. The following figure shows the typical cost distribution of German biogas plants. 

The following figure shows the typical cost distribution of German biogas plants.