Are we really headed for a hydrogen economy?

There are many technologies in the mix to remove our reliance on fossil fuels, and for a number of years I’ve been thinking of hydrogen as a front runner. I am following in footsteps the others of course. John Bockris coined the term “hydrogen economy” during a talk he gave in 1970 at General Motors Technical Center, but the idea had been kicking around for even longer than that. In a spectacularly visionary way, J. B. S. Haldane proposed hydrogen-generating windmills in 1923 for when the coal ran out, so this is an idea that has a long time coming.

But with the dramatic cost reduction of solar panels, and the emergence of batteries large and small, I’ve recently started to wonder whether the hydrogen economy has missed its time. To be sure, laboratory breakthroughs to generate hydrogen are coming thick and fast, but like the speculative battery tech I wrote about last year, none of them has been commercialised, or even scaled up in a significant proof of concept.

The lure of hydrogen is that it is essentially a fuel, so you can treat it like petrol. Or LPG, I guess, it’s a gas after all. Fuels have the benefit of being transportable, and for vehicle transport especially, allow you to quickly ‘top up the tank’. That’s the Achille’s heel of batteries but is a source of intense research because the company that brings a robust, truly rapid recharge ability to market is going to make mega-billions.

Hydrogen is also a clean fuel. Burn it and the result is water vapour. You can’t get any greener than that! And it is abundant. Hydrogen is the most abundant element in the universe, though here on Earth it is mostly locked away with an oxygen atom in the form of water. On those two attributes alone, hydrogen looks good.

Unfortunately, as a fuel, hydrogen is not particularly convenient.

Chemical strongman

While there is plenty of hydrogen in water, the bond those two hydrogen atoms share with the oxygen atom is hard to break. In fact, it takes about a third more energy to break the hydrogen bond in water than it took to form in the first place. And in a particularly ironic twist, most of the hydrogen we generate involves fossils fuels and generates CO2.

Hydrogen might burn clean and green, but how we currently create the stuff is pretty much anything but. Hence all that lab work to find better generation methods.

One of those methods is electrolysis. This is a classic chemical-class experiment, but scaling it up from a beaker at school to the industrial methods we need to power our economies is anything but straightforward. On the plus side, doing this with photovoltaic cells is a green way to generate the stuff.

On the face of it, breaking that bond is a great idea. Hydrogen packs a punch, energy-wise. It has almost three times the joules per gram than gasoline. So there is definite method in the madness, if we can make it work.

“Oh, the Humanity”

Everyone of a certain age is aware of the Hindenburg disaster, when a German airship – kept aloft by hydrogen lift cells – caught fire and was destroyed trying to dock in New Jersey in 1937.

The Hindenburg tragically highlighted one of the disadvantages of hydrogen: it is hugely flammable.

This flammability is due to hydrogen being particularly reactive, which is also an issue for general use. And being the lightest element, it is particularly flighty. Which makes it difficult to contain. Unlike oil, you cannot just pipe hydrogen around the way we do now.

Like natural gas, hydrogen must be compressed to be useful as a fuel. Unlike natural gas, which is heavy enough that we can add mercaptan to give it a detectable odour, we can’t tag hydrogen with a smelly chemical. If it is leaking, you won’t smell it. And it takes a particularly sturdy tank to store compressed hydrogen, which means thicker, which means heavier.

Compression takes energy, and when you compress a gas, it gets hot. So you need to cool the hydrogen as you compress it, which adds to the complexity of the process.

Finally, when hydrogen burns, it radiates little infrared – heat – but lots of ultraviolet. You can easily stand near a hydrogen flame and not notice, even as it’s both causing third-degree burns and giving you sunburn.

Visions of our cars as mini-Hindenburg’s is a real concern.

Fuel cell, not fuel

There is one way we can leverage the hydrogen economy and that is via fuel cells. A fuel cell converts the chemical energy from a fuel – such as hydrogen – into electricity through an electrochemical reaction with oxygen or another oxidizing agent.

It seems similar to a battery, but most batteries are self-contained. They do not need any external chemicals for them to work. Fuel cells take oxygen, usually from air, to sustain the chemical reaction.

Elon Musk is not a fan of fuel cells. He has called them “mind-bogglingly stupid” but they do offer a viable way to unlock the energy from hydrogen to drive an electric motor. The only problem is…all the other problems with hydrogen.

Imagine you are driving your fuel cell car. You are almost out of hydrogen, so you pull up to a hydrogen station and pump your car full of hydrogen in a similar way to using LPG. After five minutes, you pay and are on your way, free to drive for another 500-odd kilometres.

It is a compelling idea, and one that some vehicle manufactures are working on. And have been working for decades. Just as GM brought out their EV1 before the technology was ready for the mainstream, Honda and Toyota have been working out the kinks of hydrogen cars for years.

As examples of the concept, Toyota’s recently released Mirai and Honda’s Clarity highlight that a hydrogen fuel car looks just like any other car. By all accounts they drive like an EV, though neither has the insane off-the-line speed of a Tesla Model S. They do not have the luggage space of the Model S, either. That is one aspect of a hydrogen fuel cell vehicle that mimics our traditional gas guzzlers: the tank and ‘engine’ (in the form of the fuel cell) take up more space than batteries under the floor.

And the winner is...

Given its many disadvantages, you’re probably wondering why am I even writing about hydrogen. It is because two recent research results sparked a renewed interest.

The first is the “solar paint” created at RMIT here in Melbourne that can generate hydrogen. Synthetic molybdenum-sulphide, mixed with titanium oxide particles, allows this paint to split water vapour into hydrogen and oxygen using sunlight as the energy source. As lead researcher Dr Torben Daeneke notes, "Our new development has a big range of advantages. There's no need for clean or filtered water to feed the system. Any place that has water vapor in the air, even remote areas far from water, can produce fuel."

It is an awesome achievement, though I have not seen any details on how you capture and store the released hydrogen atoms.

The other innovation also uses sunlight, but the method is different. Researchers centred at Osaka University developed a photocatalyst for producing hydrogen from water using graphitic carbon nitride and black phosphorous. Lead author Tetsuro Majima notes that the photocatalyst produces a good amount of hydrogen, but also, "…what we didn't expect to find was that even when using low-energy light, in the near infrared, the photocatalyst continued to produce hydrogen."

I can see how this method might at least capture the hydrogen, as it is similar to the traditional electrolysis.

The hydrogen end-game

So, based on these and other innovations, am I expecting the hydrogen economy to take off?

In a word, no!

Hydrogen packs a punch, no doubt, but it is just way too hard to handle for most use cases. Compared to PV with battery storage, even innovations like those above do not sufficiently democratise electricity generation. Sure, I could use solar paint on my roof to generate hydrogen, but the risk of being on the evening news because my house exploded is very real.

It wouldn’t take too many domestic disasters of that kind to kill off the hydrogen economy. But even without that, hydrogen just seems too fussy. And fussy is hard to sell.