Dr Ruth Freeman

Well, you'd be surprised.

There's lots of different colours of hydrogen that we talk about now, not the hydrogen itself, which is a clear gas, but really how it's produced.

So people might have heard of

Blue hydrogen, which is made from natural gas, where you capture the CO2 back.

So that's seen as one form of quite clean hydrogen.

There's also green hydrogen, which is made from splitting water using renewable electricity.

But actually, most of the hydrogen that's used for fertilizer production is grey hydrogen, which is made from natural gas without capturing the carbon back.

But this story is about white hydrogen and white hydrogen, sometimes called gold hydrogen, is naturally produced inside the Earth.

And so it comes from various different geological processes.

The most well studied way that this is formed is from serpentinisation, which is a reaction where water interacts with iron rich rocks deep inside the Earth.

And so we've always known these deposits were there.

But we've always thought they were just too small and too difficult to extract to make white hydrogen a potential fuel source.

Yes.

Yeah, the colour just refers to how it's produced.

But it was back in 2012, there was a hydrogen reserve found in Mali and that natural reserve has been used since about 2012 to power a whole village because it's a natural reservoir where the hydrogen is very clean and it's actually slightly renewing as well as a pool of hydrogen.

So that's been used.

So the number of companies now exploring...

looking for potential clean hydrogen deposits has gone up.

And this is new research from the University of Toronto.

It was published in the Proceedings of the National Academies of Sciences this week.