Biogas is a sustainable and circular technology with a large potential to positively impact developing nations such as Ethiopia. However, international endeavors that initiate or install such technologies in developing nations often fade over time or even fail. This thesis evaluates what the common barriers and drivers of entrepreneurs of such edeavors are. In addition, various sustainable and circular business model frameworks and business model frameworks specific to developing nations are assessed based on their advantages and disadvantages. The results of these two research topics are translated into a list of criteria for a business model framework that addresses the barriers that are commonly faced by entrepreneurs of such endeavors and allows integrating goals of sustainability and circularity. Based on these criteria, a new business model framework is developed: the Modular Business Model Framework (MBMF) based on the Business Model Canvas by A. Osterwalder and Y.Pigneur with modules frugality, sustainability, circularity and socio-cultural aspects. The MBMF has six steps that help guide the entrepreneur through the process of setting up a business. Each module represents a larger target or goal that the entrepreneur wishes to achieve and the order in which they are applied represents their priority. The applicability and user-friendliness of the MBMF is tested by completing the case study: introducing biogas at the Nicolas Robinson School in Mek'ele, Ethiopia. Due to the civil war in Ethiopia, this case study is not implemented in the field; however, it allows to determine points of improvement for the MBMF. In addition, a review panel of experts is asked to give an indication on the tool's potential and user-friendliness. The review panel sees the MBMF as a well-argued tool with a broader potential than presented in the thesis due to the exchangeability of the modules. Several main points of improvement include limiting the amount of steps to three and adding emphasis on business resilience. The framework is also quite time consuming, but the entrepreneur is in control of the level of detail that is applied and the time spent on the framework is constructive towards setting up a new business. Future research should improve the framework based on the determined points of improvement. In addition, the tool should be tested in several real-life business endeavors and any feedback should be taken into consideration to improve the tool. Finally, the option to establish a 'library' of modules should be explored to make the MBMF applicable to almost any business.