The water thermolysis by NH3 circular.
June 12, 2026 (1) N2 + 3 H2 = 2 NH3 is circular, so practically free. dH = -92 kJ /mol, dS = - 200 J/mol * K. T 580 C. A cost of the hydrogen of the water thermolysis is a cost of the heat for reaction (2) minus a cost of electricity as a by-product of exothermic reaction (1) and totally such hydrogen product is practically free too. Really, if heat is USD 0.004/kWh, [1], and heat in electricity is 0.25 effective, and USD 0.03 /kWh sold, so USD (210 - 200) = 10 / (2 * 0.4) = USD 12.5 /ton H2 product is negligible OPEX.