Biogas Steam Reforming in Wastewater Treatment Plants: Opportunities and Challenges

Abstract

Hydrogen as an energy vector is going to play an important role in the global energy mix. On the other hand, wastewater management has become a worldwide concern, as urban settlements have been considerably increasing for decades. Consequently, biodigestion to produce biogas (rich in methane) in water treatment plants could be an interesting starting point to obtain a valuable gas that can be converted into hydrogen through steam reforming. The aim of this work was to review the main aspects concerning steam reforming of biogas from wastewater treatment plants. For this purpose, the whole chain, from water treatment to hydrogen production and purification, was considered, paying attention to the main challenges and new technologies for its optimization. Thus, a wide range of possibilities is offered, from direct energy use of syngas to high purification of hydrogen (mainly through pressure swing adsorption or membrane reactors), presenting advantages and disadvantages. In any case, the role of catalysts seems to be essential, and aspects such as hydrogen sulfide and coke deposition control should be addressed. In conclusion, biogas steam reforming applied to wastewater treatment plants is a reality, with serious possibilities for its global implementation at the industrial level, according to techno-economic assessment.