Comparison of the normalised power curves of the SSM-MFCs tested in this study (1 cm, 2 cm and cm conditions; Fig. 4a) and larger ones tested in a previous study (i.e. 4.5 cm tall electrodes [32]). The values have been normalised by the total volume of electrolyte. Green, red and blue curves stand for the 1 cm, 2 cm and 3 cm conditions, respectively conditions A, B and C. Data related to 4.5 cm (black curve) were adapted from [32] CC BY 4.0 (https://creativecommons. org/licenses/by/4.0/). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)