A green hydrogen production system based on solar-assisted biogas steam reforming

In the context of a carbon-neutral world, biogas reforming technology has potential to realize the production of green hydrogen with distributed production. Traditional green hydrogen production system based on biogas reforming dependent on high temperature condition during the reforming process; besides, biogas is always identified as a free energy resource in existing studies. This study develops a new way for green hydrogen production based on solar-assisted biogas steam reforming. The heat demand in the digester is considered in the newly proposed system; thus, more reasonable conclusion in regard to system thermal performance could be draw compared with existing studies. An advanced biogas reforming process with high steam-to-carbon molar ratio by introducing a parabolic trough solar collector is designed. At the same time, coupled with the carbon capture scheme proposed by previous study, it has great potential to realize hydrogen production with negative carbon emissions. Combined with the carbon deposition analysis, system integrated thermal performances are compared within the margin of safety. High steam-to-carbon molar ratio in the new system obviously improves the hydrogen production rate, with a maximum increase of hydrogen yield reaching 24.21 kg/h. In addition, the heat supply capacity is also significantly enhanced, which can meet the heat load of the digester when the ambient temperature is 4.03 degrees C (the reference system is only 20.19 degrees C). In terms of the integrated thermal performance, the hydrogen production efficiency of the new system is 33.60 percentage points higher than that of the reference system. This study provides a new idea for green hydrogen production from the perspectives of low temperature condition and negative carbon emissions.