Hydrogen is one of the cleanest carbon-free fuels around. It can power cars, submarines, houses etc. There’s considerable buzz around hydrogen’s capability to deliver clean energy, either by burning it or using hydrogen fuel cells. But the dominant method for producing the hydrogen we use today is not clean requiring polluting fossil fuels to make it and creating greenhouse gases.
At Glasgow University, Prof Lee Cronin thinks he and his team have come up with a game changer. Currently the most advanced process is to use proton exchange membrane electrolysers (PEMEs). But even the highest performing PEMEs need catalysts made of precious metal, high pressures and plenty of electricity.
Prof Cronin and his colleagues at the university’s Solar Fuels Group say their new method allows more hydrogen to be produced than ever before, with lower power loads and at normal atmospheric pressure and instead of remaining a gas – which requires high pressures and low temperatures to store – the new process stores the hydrogen in a carbon-free liquid.
It’s done by using a “liquid sponge” – a metal oxide that starts yellow, then turns blue as it’s loaded with hydrogen, or more correctly the potential to create hydrogen, as it holds its constituent protons and electrons. Prof Cronin holds up a beaker of blue liquid: “What you do is just turn on the electricity and you split water and you produce this liquid. When you want to produce the hydrogen, you don’t have to add any more electricity. You just pour this over a catalyst and out comes the hydrogen. And it comes out 30 times faster than the equivalent commercial device.”
So far, so startling. But while the process itself represents a breakthrough, the possibilities which flow from it are even more intriguing.
For example, Scotland is rich in potential sources of renewable energy: solar, wind and wave. But sometimes when energy is needed most, the wind isn’t blowing or it’s dark. If only we could store this intermittently bountiful energy in huge quantities. The most common way of doing this at present is pumped storage: when energy is plentiful, use it to pump water uphill to a reservoir, then when extra energy is needed let it flow back downhill again, generating hydroelectricity on the way.
But there are only so many glens you can flood and the engineering costs are high. Prof Cronin’s method offers a different future. Electricity from renewable sources would be used to split water, harvest the hydrogen and store it in a liquid for use when it’s needed.