Conversion of surplus electricity to chemical energy is increasingly attracting attention. Thereof, biological energy conversion and storage technologies are one of several viable options. In this work, the inherent challenges faced in analyzing the CO2-based biological methane production (CO2-BMP) process for energy conversion and storage are discussed. A comprehensive assessment of key process parameters on several CO2-BMP process variables was conducted. It was found that literature data often misses important information and/or the required accuracy for resolution of the underlying mechanistic effects, especially when modelling reactor dependent variables. Multivariate dependencies inherently attributable to gas-to-gas conversion bioprocesses are particularly illustrated with respect to CO2-BMP. It is concluded that CO2-BMP process modelling requires the application of process analytical technology. The understanding of the CO2-BMP mechanistic process is discussed to assist with the analysis and modelling of other gas-to-gas conversion processes. The findings presented in this work could aid in establishing a biotechnology-based energy to gas conversion and storage landscape.