**2. Materials and Methods**

To achieve the research goal, the following general scientific research methods were used: theoretical—analyses that included qualitative and quantitative approaches, generalizations, and explanations; empirical—such as description and experiment, particularly modeling; special economic and mathematical methods—factor and correlation analysis.

The data collection technique used for this study consisted of a thorough search for information through Internet search engines in various sources that are relevant to the research problem. The main source of digital data used in the study were statistical data published in a practical guide for Ukrainian farmers.

With the help of qualitative analysis, relevant research articles indexed in Scopus, Web of Science, Google Scholar, and other databases; statistical data; publications in mass media; and program documents of specialized institutions regarding the development of biogas production were analyzed. A brief overview of the dynamics of biogas production in the modern world and an overview of the current situation at the national and international levels are presented. The arguments in favor of biogas production at this stage of human development are summarized, and attention is focused on the positive effects of using biomass of agricultural origin.

An econometric model was used to model the relationship between biogas output from different types of agricultural crops and the proportion of dry matter in crops within the scope of this study—a logical (usually mathematical) description of what economic theory considers particularly important in the study of a certain problem. The choice of this tool of scientific research is due to the fact that the econometric model is a function or a system of functions that describes the correlation–regression relationship between economic indicators. At the same time, depending on the causal relationships among them, one or more of these indicators is considered a dependent variable and the others an independent variable.

Correlation analysis was applied, which made it possible to solve two main tasks: (1) to describe the dependence of the result characteristic on the factor characteristic using a mathematical equation; (2) to evaluate the closeness or density of the connection between the resulting characteristic and its influencing factors. The relationship between the yield of biogas from various agricultural crops and the proportion of dry matter in crops, as well as the potentially possible production of methane from various agricultural crops, has been established in particular.
