From the techno-economic analyses, the H2 production costs, carbon footprint and EROI obtained with TPA as a co-product are ₤0.22 kgH2 -1 , 27 gCO2 MJH2 -1 and 1.5 MJH2 MJinput - 1 (Table and S10; Figure ), respectively. The corresponding results for the alkaline pretreatment process (using data from previous reports ) are ₤ 41 kgH2 -1 , 75 gCO2 MJH2 -1 and 1.3 MJH2 MJinput -1 (Table and). These estimates indicate that the enzymatic pre-treatment holds the potential to significantly reduce the production costs for green H2 (by ~80-90% compared to alkaline pre-treatment) to a price comparable to that of grey hydrogen 39 while maintaining carbon emissions low.