SUSTAINABILITY ANALYSIS OF HYDROGEN PRODUCTION PROCESSES

Hydrogen is a versatile energy carrier and storage medium that may be employed in a variety of applications. It may be produced using different processes, each one generating a peculiar hydrogen identified by a color. In this work, process simulation is used to obtain material and energy balances for each process investigated, as well as for the evaluation of capital and maintenance costs. Process simulation outcomes are then used for to estimate three key performance indicators focusing on sustainability issues: the energy return of energy invested, the levelized cost of hydrogen and the life cycle assessment. We compared several hydrogen generation processes, each denoted by a unique color code: (i) green hydrogen, produced by electrolysis of water using electricity from renewable sources, (ii) yellow hydrogen, produced by electrolysis using grid electricity, (iii) grey hydrogen, produced from natural gas using steam reforming and (iv) blue hydrogen, like grey one, but with carbon capture and sequestration (CCS). From the results obtained it is possible to conclude that the most sustainable hydrogen production methods is the so-called green hydrogen, produced by water electrolysis.