Experimental investigation of hydrogen production integrated methanol steam reforming with middle-temperature solar thermal energy

Developing a hydrogen production method that utilizes solar thermal energy in an effective manner is a great challenge. In this paper we propose a new approach to solar hydrogen production with the integration of methanol steam reforming and middle-temperature solar thermal energy. An experiment on hydrogen production is conducted using a 5-kW solar reactor at 150-300 °C under atmosphere pressure. The 5-kW solar receiver/reactor is fabricated and positioned along the focal line of one-tracking parabolic trough concentrator. As a result, the chemical conversion of methanol can reach levels higher than 90%, and the volumetric concentration of hydrogen in the gas products can account for 66-74% above the solar flux of 580 W/m2. The obtained maximum hydrogen yield per mole of methanol is 2.65-2.90 mol, approaching the theoretical maximum value, and the experimentally obtained thermochemical efficiency of solar thermal energy converted into chemical energy is in the range of 30-50%, which is competitive with other high-temperature solar thermochemical processes. A kinetic model of solar-driven methanol steam reforming related to solar flux is also derived based on the experimental data. The promising results demonstrate that this solar-driven hydrogen production method can be feasible in practical applications.