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02 June 2021

Somewhere over the Rainbow

This article was written by Bill Prast. All views and opinions expressed are strictly his own.

In the rainbow of carbon-neutral scenarios being embraced enthusiastically by the general public, a rising claimant for attention as the fuel of the future is that most abundant element of them all, hydrogen.  The good news is there is a lot of it.  Almost three-quarters of the mass of the universe apparently is hydrogen.

Helium is a distant second at one-quarter of everything but helium is inert, alas, and there isn’t much here on earth anyway.  The rest of the periodic table (thank you, Dmitri Mendeleev) is the remaining two percent including the naughty elements like carbon, sulphur, and uranium.  Not to mention all those metals and non-metallics which we like to have on hand.

Since hydrogen is extremely flammable, it would seem to be an ideal fuel.  The Hindenburg zeppelin disaster of eighty years ago was just an accident, right?  Let’s ignore fire safety matters for a moment.

How do we get our hands on lots of hydrogen?  Being the simplest molecule, it likes to form bonds and does so with ease.  Take a sip of your hydrogen-laced glass of water or cup of tea while you read.

Dismantling the compounds containing hydrogen is not too complicated.  Costly, maybe, and it’s not the easiest gas to isolate, compress, transport, or store.  Much trickier than liquefied natural gas.  But to get hydrogen, there are a few colourful ways to proceed.

The classic way it’s done – known as Grey hydrogen – begins with natural gas.  Extract the hydrogen by thermal reforming and then dispose of the unwanted carbon dioxide by venting into the atmosphere.  That’s how we get 95% of our hydrogen now.

To avoid discharging carbon dioxide, we move on to the currently popular alternative of Blue hydrogen.  You start with natural gas but you go the carbon capture route, somehow.  It’s in vogue.

There are other, equally colourful choices.  How about Green hydrogen?  Begin with water, split it by electrolysis, keep the hydrogen and vent the harmless oxygen.  There is no carbon involved.  To do this, you need lots of energy, which could be from a renewable source.  It is very energy-intensive but the energy source is a matter of choice.

How about Pink hydrogen?  It’s a variant of Green hydrogen, using nuclear power as the exclusive energy source.  And let’s not forget Yellow hydrogen which is also Green hydrogen, employing solar as the power source.

Personally I think the commercial sequence will be to shift from Grey, where we are now, to Blue for a while and ultimately to Green, using a variety of renewable energy sources (maybe Yellow but not likely to be Pink).

But the timetable, the technology to achieve commercial scale and the basic economics of a hydrogen business venture are beyond me.  Can we foresee solar panels to permit the electrolysis of water into its elemental components, oxygen and hydrogen?  Maybe.

Without wishing to appear to harp on the Hindenburg fire of two generations ago, today’s energy policy desk jockeys have to understand this is a dangerous gas that requires advanced engineering to control its safe use as a transportation fuel.  The same has been true since the nineteenth century for petrol and diesel, of course.

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