Another, still unexplored, reaction mechanism involves anaerobic ammonium oxidation on anodes of bio-electrical systems. Such systems can be microbial fuel cells or microbial electrolysis cells. In the absence of dissolved oxygen, nitrite, or nitrate, microbes living in the anode compartment are able to oxidize ammonium to dinitrogen gas (N2) just as in the classical anammox process. At the same time, they unload the liberated electrons onto the anode, producing electrical current. This electrical current can be used either directly in fuel cell mode or for hydrogen and methane gas production in electrolysis mode. While there is no clarity on the reaction mechanism behind, one hypothesis is that nitrite, nitrate, or dinitrogen oxide play a role as intermediates. However, since the process occurs at very low electrochemical potentials, other, more speculative, reaction mechanisms seem possible as well.