As hydrogen is one of the most clean fuels and energy storage mediums of all, producing it is a challenge for both already established companies in the area and for the “newbies”. Such a newbie is H2 Power Systems, based in the UK, that has designed an on-site and on-demand hydrogen producing system based not on electrolysis, but on thermolysis, which is the splitting of water at very high temperatures.
Water can be split up in some degree at temperatures beginning with 1800°C. By adding certain catalysts, the quantity of hydrogen/oxygen obtained can be increased – at least theoretically.
The graph below, taken from their explanatory PDF here, shows the relation between temperature and the quantity of gases resulted from thermolysis (click to enlarge it).
H2 Power Systems’ idea is to use solar power through a solar concentrator they call H2P, having a light concentration factor of 5500, heat the steam at 2200°C, and extract the two gases.
“For pure water, sizeable dissociation occurs above 1800°C. The number of dissociated molecules increases with temperature. However, if the temperature is lowered, the components recombine very quickly. At 2500K and 0.68 MPa, it takes 5.97 KWh to split one kilogram of water and
to separate the hydrogen and oxygen produced in the thermal water splitting.
The main challenge is to separate the hydrogen when it is there. H2P uses selective membrane filters for effective gas separation. Such membranes are available for temperatures up to 1000°C and research groups in Israel and Japan have recently studied their use for thermal water splitting. However, we produce our own high temperature membrane filters.”
Electricity is then produced by using a fuel cell, which, as these researchers say, will last longer if used with the pure oxygen and the pure hydrogen their system outputs, as there is no carbon involved in the production process.
H2 Power Systems is just at its beginning, and these plans are to be turned into a prototype in about six months. Until then, it’s all on paper and partially achieved (everything but the solar furnace). Also, the figures in the graphic above are approximate and theoretical, but they should be able match the future reality. We’ll follow them as they develop along.