Solar for hydrogen production

Picture this. An open pit or underground mine in Australia, Africa or the Middle East ten years from now. All day every day water is pumped out to keep it dry because it is below the groundwater table. Ten years ago (that’s now!), this waste water was a cost and a nuisance to the mine operators because it was hard to dispose of.

The future mine’s energy needs (40 MWe of electricity for activities such as rock comminution and ventilation, plus fuel to run light vehicles, medium sized machinery and large 200t dump trucks) are supplied by hydrogen, and the hydrogen comes from the waste water that used to be a problematic waste stream. The salty groundwater becomes a feedstock that supplies all the energy needs in the mine, using only sunlight and a non-consumed catalyst. What’s more, the hydrogen is produced using a technology that needs no power or heat and doesn’t even need pure water.

This mine becomes the exemplar that sees (over the following 10 years) sea water and photocatalysis hydrogen facilities across the globe helping transform the global energy mix.

Large scale production of hydrogen from a source that is not fossil fuel-based requires the feedstock to be water. To get hydrogen from water requires the water to be ‘cracked’ or ‘split’ into hydrogen and oxygen. This can be done in a number of ways, including heating it to a very high temperature (thermolysis), sending an electric current through it (electrolysis), or reacting it with a light absorbing material (a photocatalyst) to achieve photochemical splitting (or photocatalysis). Independent assessments of the methods to split water conclude that photocatalysis is the most promising technology to do this at a cost that is competitive to the current dominant industry practice of steam methane reforming, with a vastly reduced carbon footprint.