The dataset contains a register of biogas plant sites in Lower Saxony with spatially-resolved and high up-to-date plant information. The register is intended to create a basis for identifying power-to-gas (P2G) potential for biogas plant sites. The dataset is being done within the context of the research project H2-FEE: Flexible energy carriers for the energy transition (running from July 2022 to presumably June 2025) funded by the Lower Saxony Investment and Development Bank (Investitions- und Förderbank Niedersachsen, NBank).