Biogas Plant Modelling for Flexibility Provision in the Power System of Bornholm Island

Abstract

Biogas power plants play a vital role in the structure of integrated energy systems to further decarbonize the energy sector. On the one hand, they can facilitate the broad integration of variable renewable energy sources; on the other, they directly interlink different energy domains and provide multi-energy services. This paper provides an overview on the possibilities and potentials of biogas power plants in providing flexibility towards islanded power systems. To this end, we present a model that includes the most relevant dynamics from an electrical engineering perspective. For a given infeed of raw material, it is able to characterize the anaerobic digestion processes and quantify the energy output in order to evaluate the plant's flexibility potential. The model is validated against real data from a 3-MW biogas power plant on the island of Bornholm, Denmark. The results show that actual on-site measurements in terms of biogas production as well as electrical and thermal output may be matched by the presented model. Furthermore, the paper gives a detailed overview on the estimated biomass potential of the island of Bornholm, as well as the flexibility assessment of the entailed biogas operations.

Empirical Validation of a Biogas Plant Simulation Model and Analysis of Biogas Upgrading Potentials

“…This paper extends the analysis presented in [16] by providing in-depth information on the internal processes of the Bioenergi biogas plant on Bornholm as well as a detailed validation of the subsequent processes with high-resolution empirical data. Moreover, the paper critically reviews the influence of modeling assumptions and gives an outlook on the energy potentials for biogas upgrading for the investigated site.…”

“…In the current structure of the plant, the average substrate composition consists of 70.48% cow slurry, 19.82% of pig slurry, 6.17% of slaughterhouse waste, 3.30% of corn and 0.22% of fish waste, with an average percentage of total solids in the feedings of 12-14%. The island of Bornholm has a large feedstock potential both from animal husbandry, household wastes and secondary crops which is currently not fully exploited: from a total estimated amount of 741,425 tons the biogas plant currently has a permission to treat only 120,000 tons per year [16]. Next, the slurry is pumped from the arriving trucks into the receiving tanks, which are concrete tanks inset into the ground with a total capacity of 2100 m 3 .…”

“…Figure 5 illustrates the modeling approach presented in this paper. Detailed theoretical background information and analysis of the biomass potential on the island of Bornholm are given in Zepter et al [16]. The model takes daily or hourly time series of the infeed as input.…”

Biogas Plants in Renewable Energy Systems—A Systematic Review of Modeling Approaches of Biogas Production

“…Reference [99] used a time-dependent biogas production flow rate, modeled as exponential function. The biogas volume flow rate depended on feedstock properties, e.g., the organic fraction, its biogas production potential and maximum biogas production rate.…”

Energy Self-Sufficient Livestock Farm as the Example of Agricultural Hybrid Off-Grid System

“…Fermentation, however, is an unstable process as it may be disturbed by an increase in temperature in a fermentation chamber, overproduction of volatile fatty acids, and chemical contamination, e.g., with pesticides or heavy metals [4]. The by-product of this process is digestate, which is a valuable organic fertilizer that is a source of easily digestible nutrients for plants [3,5,6]. Biogas plants, unlike other renewable energy sources, are multi-energy systems as they produce biomethane, which, after combustion, provides electricity and heat through the process of cogeneration [5].…”