Electricity generation with microorganisms in the form of microbial fuel cells (MFC, release of electrons to the working electrode) has been known for over a century and has been studied many times. Microbial electrosynthesis (MES, absorption of electrons from the working electrode), on the other hand, has only been studied in more detail for a few years, with the previous focus being primarily on bioremediation. The uptake of electrons from an electrode or from a chemical substance (electron mediator) shifts the redox balance of the microorganism's pyridine nucleotide pool towards NADH. Due to this increased availability of reduced cofactors, the MES systems can be used for the production of reduced products such as butanol and ethanol. Bioelectrochemical systems (BES) do not yet exist on an industrial scale. However, various authors have made initial economic considerations for BES on a large scale. The authors calculated that the current price per electron in a BES is lower or comparable to the price of an electron obtained from sugar (sucrose). Only cathodic reactions were considered; additional added value from an anodic reaction or the provision of electrons at the anode by microorganisms was not included. Initial dimensional calculations using the example of lysine production also achieved comparable fermenter sizes for a BES and conventional fermentation with cost savings of 8.4 % in Europe and 18 % in the USA when using the BES. Electro-biotechnological processes could therefore enable cost-effective production of basic chemicals and biofuels in the future. The Department of Bioprocess Engineering has been working for several years on the development of new types of reactors for electro-biotechnological processes, the investigation of electron transport processes and product formation using a potential.