The third technology (GEN 3) refers to the electroreduction of N2 to ammonia via direct or mediated means: the Haber-Bosch process is no longer necessary and the source of H is water.
The electrochemical nitrogen reduction reaction (eNRR) in which an electro catalyst allows the direct addition of electrons and protons to the N2 molecule which can be replaced by indirect or mediated mechanisms in which a redox mediator such as Li+; it is first reduced and then regenerated through a series of reactions. The physical configuration of eNRR cells has much in common with water splitting technology and therefore uses similar design and construction principles.
The eNRR process, in principle, has the potential to operate with higher energy efficiencies than the GEN 2 and GEN 1 processes. However, at the electrochemistry level, it should be emphasized that eNRR processes, whether direct or mediated, require more overvoltage: they require energy in excess of the minimum thermodynamic energy.
