Figures 4A, B show increasing additional bias would decrease the overall efficiency. It seems In the EET-mediated system only fuphill of the electrons actually get promoted to reduce any carbon substrates in the form of NADH, that’s why H2-mediated systems typically show less excess potential given the same current density one wishes to apply. However, the proportion to which the H2-mediated bias is affected is less than that of the EET-mediated bias for the equivalent values. It should also be noted that the equivalent amount of additional bias that is put into the EET-mediated system results in greater efficiency losses as seen in Figure 4B.