Since I first published an article on this subject I've been taken to task by a young family member for being too negative about the prospects of a Hydrogen Economy, mainly because I failed to mention 'clean green hydrogen' generated from surplus electricity, employing electrolysis.
Back in 1874 Jules Verne had a similar vision but failed to identify the source of the energy, 'doubtless electricity', required to disassociate the hydrogen and oxygen.
Coal; oil and gas; peat; wood; bagasse; wind; waves; solar radiation; uranium; and so on; are sources of energy. But electricity is not.
Electricity (and hydrogen derived from it) is simply a means of transporting and utilising energy - see How does electricity work? on this website.
The Mysterious IslandJules Verne 1874 “But now, my dear Cyrus, all this industrial and commercial movement to which you predict a continual advance, does it not run the danger of being sooner or later completely stopped?” “Stopped! And by what?” “By the want of coal, which may justly be called the most precious of minerals.” AT THIS POINT THEY ARE REASSURED - THERE IS PLENTY OF COAL FOR THE TIMEBEING “That is reassuring for us, but a bad look-out for our great-grandchildren!” observed Pencroft. “They will discover something else,” said Herbert. “It is to be hoped so,” answered Spilett, “for without coal there would be no machinery, and without machinery there would be no railways, no steamers, no manufactories, nothing of that which is indispensable to modern civilization!” “But what will they find?” asked Pencroft. “Can you guess, captain?” “Nearly, my friend.” “And what will they burn instead of coal?” “Water,” replied Harding. “Water!” cried Pencroft, “water as fuel for steamers and engines! water to heat water!” “Yes, but water decomposed into its primitive elements,” replied Cyrus Harding, “and decomposed doubtless, by electricity, which will then have become a powerful and manageable force, for all great discoveries, by some inexplicable laws, appear to agree and become complete at the same time. Yes, my friends, I believe that water will one day be employed as fuel, that hydrogen and oxygen which constitute it, used singly or together, will furnish an inexhaustible source of heat and light, of an intensity of which coal is not capable. Some day the coalrooms of steamers and the tenders of locomotives will, instead of coal, be stored with these two condensed gases, which will burn in the furnaces with enormous calorific power. There is, therefore, nothing to fear. As long as the earth is inhabited it will supply the wants of its inhabitants, and there will be no want of either light or heat as long as the productions of the vegetable, mineral or animal kingdoms do not fail us. I believe, then, that when the deposits of coal are exhausted we shall heat and warm ourselves with water. Water will be the coal of the future.” |
Then in 1923, scientist and polymath, J B S Haldane, rectified this rather serious shortcoming: an inexhaustible source of heat and light; by proposing a network of electricity-generating windmills to produce hydrogen for distribution in Britain.
To a schoolchild it seems very attractive:
Hydrogen can be produced in any high school science lab (or kitchen) in a tub of water with two electrodes, topped by inverted test tubes (or jam jars), and a battery charger. We all did it as kids.
And when you burn it (or explode it, by mixing it with the oxygen - don't) you get energy and your water back.
Although for blowing up our balloons aluminium and caustic soda in a bottle worked better, as it produces its own pressure ( 2 Al + 6H₂O → 2 Al(OH)3 + 3 H₂ - put a ball of steel-wool in the neck to filter any droplets).
And of course, as NASA will attest, hydrogen is also a pretty good rocket fuel, perfect in some conditions, but not for high powered boosters.
Yet as we demonstrated, with a burning tail on our hydrogen balloons cast aloft, and Nazi Germany famously demonstrated with a Zeppelin, it's quite inflammatory: "Oh the humanity!"
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As young adults we were all enthusiasts. Hydrogen offered a means of transporting energy, perhaps in a pipeline.
Yet it's been a century and a half since Jules Verne and the long prophesised Hydrogen Economy still remains a mirage - always in the distance - shimmering just beyond the desert horizon.
It turns out there were one or two dunes yet to climb.
The principle problem seemed to be storage. You need to keep it cryogenically, at below -253°C, or compress it to 70MPa. Yet it's a very common feed-stock in the chemical industry (and at NASA) and they manage it. And then there were the light metal hydrides, that resemble hydrogen batteries - you put it in and take it out when you need it. But it turned out that they were not so light.
So it's been a hard sell. As a transport fuel hydrogen is not nearly as: easy and safe to transport and store; energy efficient; or energy dense as carbon containing fuels like petrol; dieseline; or a hydrocarbon gas (eg LNG, LPG or Methane).
These hydrocarbons produce both H₂O (water) and CO₂ (carbon dioxide) when (fully) burned; whereas 'clean green hydrogen' just burns to water.
This was attractive to a shop-floor politician or the commerce educated CFO of a corporation. And many scientists and some engineers just want to experiment or to make a working prototype. They don't care about the overall economics or energy balance.
Consequently there have been many many trials. There are hydrogen powered trains and busses. Ford and GM produced hydrogen fuelled cars - for a while. Toyota is at it again.
What went wrong?
The short answer is - physics. As school children we didn't notice that we got back just a tiny fraction of our battery charger's energy.
Using electricity to make hydrogen and then hydrogen to make electricity (to drive wheels) adds two, very energy consuming, steps to just using the electricity directly. Using hydrogen in an internal combustion engine to drive the wheels is even less efficient.
Modern batteries on the other hand, lose a lot less conversion energy, back and forth, and allow for regenerative braking, recovering up to 20% of that committed to getting the vehicle moving. Ask Elon Musk at Tesla.
Dr Ulf Bossel has done this energy comparison for us (very comprehensively) in: Does a Hydrogen Economy Make Sense? (attached below).
In the former case (using hydrogen) over three quarters of the electricity is lost to the intermediate processes mostly as heat. Using batteries the reverse is the case. Around a quarter of the energy is lost to conversion and battery losses, leaving three quarters of the energy available for use in an electric car or to power a building or factory (for example to cover peak loads).
Thus due to energy losses storing surplus electricity as hydrogen is seriously uncompetitive with battery storage - as several Australian and international commercial energy providers have already decided.
That's not to say that there is no prospect for hydrogen. For example, biologically generated hydrogen, using sunlight and bacteria or algae, shows some promise and some industrial processes currently employing carbon for reduction, like iron making, can be decarburised, at a significant additional cost, by using hydrogen in place of carbon monoxide.
Iron is the main component of steel (typically over to 90%) and steel is the most fundamental material enabling the modern world. This world supports around seven billion more human lives than were supported before the industrial revolution.
World production of steel is presently around 2 billion tonnes per year, around half of it in China. Each tonne of steel produced emits around 1.9 tonnes of carbon dioxide (about 8% of total energy related greenhouse emissions).
Direct reduction iron processes that replace conventional blast furnace technology and eliminate coke ovens, are already commercially competitive in some situations and have a smaller 'carbon footprint'. But these still rely on carbon monoxide, together with hydrogen, to strip oxygen from iron ore. Pure hydrogen would work on its own but would be commercially untenable at present.
But my real gripe is not with so called 'green hydrogen', produced as Haldane suggested, by electrolysis, using over-produced energy from wind turbines (Haldane's windmills) or other remote green sources like: solar panels or waves, from whence hydrogen might be piped to distant markets to avoid extreme grid losses.
My concern is with hydrogen produced by 'steam reforming', employing hydrocarbons or coal. This is how over 90% hydrogen used today is produced. And it's how it's proposed that Australia produces hydrogen for export. Used as a transport fuel this 'dark hydrogen" releases more than double the carbon dioxide to deliver the same power to the wheels, than does a conventional petroleum fuelled vehicle; or even an electric vehicle that is charged from the grid using 'dirty' coal fired power. It's the opposite of 'green'.
A recent article in NewScientist: 'A hydrogen fuel revolution is coming – here's why we might not want it' provided some colourful categories to the present sources of hydrogen.
You need to subscribe to read the entire article at NewScientist but these lines caught my attention:
| Only 4 per cent of hydrogen is made ... using electrolysis to split it out of water. Much of the electricity to supply even that measly share of the hydrogen market comes not from green sources, but from fossil fuel power plants. Far from being green, the hydrogen produced globally today has a carbon footprint on a par with the UK and Indonesia combined ... about 830 million tonnes of CO2 annually.
That brings us to the strange point where transparent hydrogen gets colourful, at least linguistically. “Grey” hydrogen is so-called because it is made from fossil fuels using steam reformation. It costs about $1 a kilogram. “Blue” hydrogen typically “buries” the emissions associated with producing it using carbon capture and storage (CCS) technology – an approach which exists, albeit only on a pilot scale so far – for about $2 per kilogram at the cheapest*. Finally, there is “green” hydrogen, produced by electrolysers running off renewable electricity. For the most part, this costs upwards of $4 a kilogram. When it comes to decarbonisation, “there’s no point in grey hydrogen”, says Rob Gibson at National Grid ESO, which runs the UK’s electricity transmission network. But a move towards large-scale green hydrogen production would be very costly, says Evangelos Gazis at Aurora Energy Research in Oxford, UK. This is where blue hydrogen comes in. “If we want to reach scale, probably [blue] will be inevitable,” says Gazis. Others, such as Ralf Dickel at the Oxford Institute for Energy Studies, make the case that blue hydrogen is needed in the short term because using renewable electricity to displace coal and gas power plants achieves deeper CO2 curbs than using it to make green hydrogen... Others see blue hydrogen very differently. Because it still involves extracting gas, oil and coal, Friends of the Earth Europe has branded it “fossil hydrogen”, a lifeline for struggling fossil fuel firms. |
as CCS, on any scale sufficient to make a difference to global warming, is totally impractical,
in addition to being potentially very dangerous and environmentally harmful.
That's why back in April 2018 I was surprised to see a handful of senior politicians: including the Liberal PM and a handful of Labor Victorians (it's bi-partisan), gathering in Morwell in Victoria to announce that jobs in the Latrobe Valley have been saved by a Japanese consortium that will build a pilot plant to convert brown coal to hydrogen. Read Here...
Fans of the Reverend Dodgson's (Lewis Carroll's) work will recall some 'weird shit' in Wonderland like: Alice growing and shrinking; a disembodied cat; and babies turning into pigs. She's seen here with Frank L Baum's Dorothy, and her little dog Toto. I was feeling a sudden affinity for Dorothy who involuntarily found herself in OZ, whence she unsuccessfully attempted to escape from the weird inhabitants in a hot air balloon. But where were my ruby slippers?
Yet these bizarre adventures are put into the shade by Alice's in: Through the Looking-Glass. So I had to pinch myself to check that our screen had not somehow turned itself into Alice's looking-glass and sucked me through to the other side.
Hydrogen from coal (carbon) - really? Surely they mean hydrogen from water. You know:
H₂O + C → H₂ + CO
Fortunately, even in OZ, water and carbon do not spontaneously combine like this, otherwise there would be no coalmines; and no carbon cycle; and no life on Earth. The reaction is endothermic. In other words it consumes/requires energy (a lot of it) to proceed. This is the useful energy released when the hydrogen is re-oxidised to water when: burnt; in an engine; or in a fuel cell.
Back in the Rev's day, right through to my young adulthood, hydrogen was made in a great many places called 'gasworks' that produced 'producer gas'. All the reaction needed was a lot more carbon (coal) and oxygen (from the air) to generate the additional heat required: 2C + O₂ → 2CO + heat (energy). As Shaw's Eliza Doolittle opined: "Lots of coals makin' lots of 'eat, wouldn't it be lover-ly"
The principal product of the process: CO, carbon monoxide, is poisonous. That's why we have catalytic converters in our car exhausts to convert the CO to CO₂ (carbon dioxide) by sucking in some of that good old O₂ from the air.
In Alice, Dorothy and Eliza's day this was not thought to be a problem. Pipes were laid in the street and the mixture of hydrogen and the carbon monoxide was distributed to peoples' homes to light their gas mantles (for light); to provide room and water heating; and to use in their gas oven - principally to cook their meals. It also provided a convenient suicide means when it all got too much - just put one's head in the oven.
The poisonous CO component was soon removed in the home by burning it, consuming oxygen, to convert the 'town gas' into relatively harmless CO₂ (carbon dioxide) and H₂O (water).
Even though it's yet another century, like Alice and Dorothy I feel like I'm seeing some 'weird shit' - this time on TV and on the Web.
Didn't we decide way back in the fifties that if we burnt the coal near the mine and produced electricity instead, it would be more useful and a lot less messy? And if our power station was more efficient than a gasworks we would not have to consume as much carbon to get equivalent utility. For example, might electric lamps be more efficient than gas mantles? Might microwave or even electric ovens be more efficient than gas ovens? Not to mention that it's a bit hard to power a valve radio or IBM 360 with gas.
But times change and we're about to close the very large coal burning Loy Yang Power Station power-station, constructed as recently as 1985, because it produces too much carbon dioxide for each MWh of electricity produced.
I haven't seen Kawasaki Heavy Industries proposed design but I'm guessing it's based on well-established coal gasifier technology where burning coal is treated with steam and controlled amounts of air or pure oxygen, under high pressure, to produce a mixture of carbon monoxide/dioxide and hydrogen - a sort of upgrade on the old gasworks we learnt about in high school chemistry.
There's no particular mystery to making and separating hydrogen this way. The room I'm in is a kind of town-gas separator. It once had a gas mantle lamp plumbed into the wall. If a careless person left the unlit gas on, the carbon monoxide sank to the floor and the hydrogen potentially filled the upper part of the room where it became an explosion hazard. As a result of several such disasters those cunning government officials at the turn of the 19th century required that ventilators 'shall be installed near the ceiling' in Australian gas-lit homes to avoid such repercussions. Today our lamps are all LED but the ventilators, prettily decorated in Art Nouveau style, still look down on me as I write.
Sure, the old processes were inefficient and seriously polluting, in addition to being financially challenged by newer technologies. But the basic chemistry remains unchanged, as does the physics. So how will a gas plant, in which the carbon dioxide is a huge by-product in the reduction of relatively modest amounts of hydrogen†, produce less carbon dioxide from a similar amount of coal?
In this 21st century version, instead of piping the gas out to Alice and Eliza, or producing electricity locally, the hydrogen is to be separated and compressed for shipment to Japan.
Yet efficiency, cost and impact on the environment remain significant hurdles.
And if it's so good why not just gasify the coal like this then turn the hydrogen into electricity in big fuel-cells locally, like Elon Musk's big battery in South Australia, thus avoiding all that compression and shipment to Japan for use in fuel cells in Japanese cars?
Wait a minute, that's not a new idea. Isn't that sort of what happens in modern combined-cycle thermal power stations? And aren't there an awful lot of failed combined-cycle thermal power stations? See Here...
In particular, isn't the high capital and maintenance cost of these often uncompetitive with modern super-critical designs? The latter are quite a bit cheaper to build and run; achieve similar overall efficiency and produce a similar amount of CO₂ for each MWh of electricity generated - quite a bit less than older designs like Loy Yang.
Like Alice in Through the Looking-Glass we seem to be back at square one yet again. We would get more, lower cost, electricity per tonne of CO₂ if we just build a modern super-critical thermal electricity generation plant. Oh, I remember electricity from coal - that's no good - that's where we began. So how's this thing any better?
If you've been paying attention you know the mantra - clean coal. Here comes CCS, carbon capture and storage, again. Just dump the nicely separated CO₂ into the depleted Bass Straight oil fields - "come to my arms, my beamish boy!"
Yet there are one or two problems with this. Tweedledum and Tweedledee have been spruiking carbon capture and storage for years and, as ever, the problem is not the technical practicality of doing this. The problems are of scale including: capital cost; energy cost; the massive volumes of CO₂ produced when coal is burnt; as well as serious environmental and safety concerns.
Yet for me the main disjunction is that this pilot 'coal to hydrogen' plant is being spruiked by our pollies as the start of a trillion dollar industry employing thousands. Surely, in this event, the new industry will release far more carbon to the atmosphere than Loy Yang ever did.
Technical Footnote
† Assuming full carbon oxidisation: 2H₂O + 2C + O₂ → 2H₂ + 2CO₂
And to provide the energy required for the reaction (> 131 kJ/mol) let's burn some more carbon: 2C + 2O₂ → 2CO₂
Combined: 2H₂O + 4C + 3O₂ → 2H₂ + 4CO₂ = (8O; 4C; 4H)/4 = 2O; 1C; 1H
Thus two Oxygen atoms and one Carbon atom are required to liberate each Hydrogen atom.
The atomic weight of common Carbon is 12; that of Oxygen 16; and that of Hydrogen 1.
Thus to produce one tonne of hydrogen for export will create at least 44 tonnes of CO₂ (12+16x2) to be disposed of - and probably a lot more - to make up for thermal inefficiency.
This is before additional fuel and/or electricity is consumed for compression of the gasses; required for transport and for injection of the by-product CO₂ into an oilwell.
Given that the by-product carbon dioxide is by far the heaviest and most voluminous material to be dealt with, logistically the best location for the plant could be on an oil platform in Bass Straight.
At about half the weight of the CO₂ produced and much easier to store, transporting the coal to the plant is the least problematic of the materials handling issues. Maybe the best solution would be to export the coal to Japan?
I've received some criticism about this - so you don't have to believe me - attached (below) is a much more comprehensive analysis, by a more impressively qualified expert: "Does a Hydrogen Economy Make Sense? by Ulf Bossel
| Ulf Bossel has a Ph.D. in physics University of California, Berkeley, he was first president of the German Solar Energy Society; he joined Asea Brown Boveri (ABB) new technology group in Switzerland developing fuel cells; he was convener of the European Fuel Cell Forum in Lucerne, Switzerland; later a freelance fuel cell consultant, with clients in Europe, Japan, and the United States. |
For a supportive review (in Phys.org): Click here... To download the whole paper: Click here...