# Eligible technologies Projects eligible under this methodology are the anaerobic digestion sites where feedstock inputs are collected, anaerobic digestion occurs, and biogas/energy is generated. The Project Developers are the operators of the anaerobic digestion sites. The only use of biogas eligible in the current version of the methodology is **purifying biogas to biomethane and direct injection into the gas grid.** Other uses may be considered on a case by case basis, if Project Developers provide sufficient proof that they 1) still adhere to the eligibility criteria and 2) have a rigorous, conservative GHG reduction quantification method for components that differ from the method described in the present document. The only use of digestate eligible for carbon credits under this methodology is application to agricultural soils as an organic amendment and fertilizer. Such activities shall be credited with avoided synthetic mineral fertilizer production and use. If digestate is used in a different application, the project is still eligible for credits on the basis of their energy production activities. ## Project Scope One project corresponds to one anaerobic digestion site. It is not possible under this methodology to group multiple sites together as one project. An anaerobic digestion site is defined as a site with one operations permit and shared infrastructure (e.g. digestion tanks, storage, and treatment facilities). Only the activities at the biogas site that are deemed additional are part of the project scope. Projects certified under this methodology shall have a maximum crediting period duration of 5 years, which can be renewed for a total of 20 years. See the [Crediting Period Renewal](/rainbow-standard-documents/procedures-manual/project-certification-procedure.md#crediting-period-renewal) section of the Procedures Manual for procedural details. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.rainbowstandard.io/methodologies/biogas-from-anaerobic-digestion/eligible-technologies.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.