Energy storage is currently one of the most significant problems associated with mass-scale usage of renewable (i.e. wind and solar) power sources. The use of hydrogen as an energy storage medium is very promising, but is hampered by the lack of commercially available hydrogen-to-electricity (H2e) converters. Here we are presenting the first commercially viable, biologically based technology for H2e conversion named the BioGenerator. It is a microbial fuel cell based on electron consumption resulting from the respiration of chemolithoautotrophic microorganisms. The results obtained during the scale-up study of the BioGenerator showed a maximum specific current of 135 A/cm(2), maximum power density of 1800 W/m(2) and stable electricity generation over a period spanning longer than four years. The largest unit studied so far has a volume of 600 L and a power output of 03 kW. (C) 2017 Elsevier Ltd. All rights reserved.