H2-rich biogas production from fixed bed wheat straw pyrolysis and the potential of produced biochar as H2 storage material

• High H 2 rich (86.07 vol%) biogas was produced from waste wheat straw pyrolysis. • High temperatures and pressure lowered carbon conversion; CO 2 yield reduced to 0.16 vol%. • Biochar produced can store up to 15.29 mol/kg H 2 at cryogenic temperature. H 2 is a clean energy source, and is targeted as one of the ways to transition from fossil fuels. However, there are drawbacks in production and storage of hydrogen. To cover the supply, we need H 2 from many resources and because of its low density we need materials that can store bulky quantities of H 2 . Here we investigated the potential of a renewable source (waste wheat straw) to produce and store H 2 through pyrolysis and adsorption. The impact of pressure and temperature (500–900 °C, and 1.01–30 bar range) on the selectivity of H 2 rich gas production was systematically investigated; and temperature displayed more influence towards H 2 formation. Increasing temperature and pressure increased H 2 production (which peaked to 86.07 vol% at 800 °C and 30 bar). The surface area and pore volume of the by-produced biochar increased with temperature; thus, the biochar was tested in terms of its H 2 storage capacity (at atmospheric and cryogenic temperatures, i.e. 30 °C and −196.0 °C and under vacuum to 70 bar pressure). The maximum H 2 adsorption capacity at ambient temperature was 2.50 mol/kg at 66.33 bar (for 900 °C biochar) which significantly increased to 15.29 mol/kg at cryogenic temperature at 46.21 bar. This study therefore provides fundamental data and novel methods with which H 2 can be produced and stored, thus aiding in the full-scale implementation of a hydrogen economy.