What is green hydrogen?

Some more useful material from Global Mining Research:

When you think of hydrogen, one of the things that we have at the back of our mind is the Hindenburg disaster, however the world has come a long way since 1937 (the Hindenburg was in fact supposed to use helium but there was a US export restriction). There are clear advantages for hydrogen with its high energy density, but also drawbacks including being highly flammable and then there are the storage challenges. Conventional production of hydrogen is from hydrocarbons (e.g. methane) but this produces CO2 / CO as a by-product and therefore is polluting. By comparison green hydrogen looks to produce hydrogen from processes such as the electrolysis of water using renewable power sources with benign by-products.

Why is green hydrogen relevant to the resources sector? This comes back to some of the old and newer rules of mining investment. Firstly, that energy is around a third of the cost of any mining operation. Secondly, mining companies today are measured on their environmental and social footprint (just ask RIO). The potential applications of hydrogen in the mining industry is wide from the potential for haul trucks (e.g. AAL) and trains to run on hydrogen to site power generation. It could be argued this is the natural evolution, as increasingly mines adopt renewable power solutions (e.g. solar).

As highlighted in the chart below one of the principal selling points for hydrogen is its very high energy density. That is 1kg of hydrogen contains multiples of the energy potential when compared to other fuels, or lithium ion batteries. Hydrogen can be used in fuel cells or internal combustion engines (ICE). Further, when burned in air the by-product is water (2H2 + O2 → 2H2O + energy).

In addition to benign by-products, a big driver of the resurgence of hydrogen as a potential power solution is the use of renewable “free” or low-cost power. This acts to drive down the production cost of hydrogen when compared to the current steam methane reforming process.

Using renewable electricity to create hydrogen from the electrolysis of water is not a new technology and has been around since the 1800’s. Essentially, apply a direct current through electrodes placed in water and – voilà – hydrogen gas forms at the cathode and oxygen gas at the anode.

The rough maths is 1 kilogram of hydrogen requires 9 litres of water and ~55kWh of electricity. The real cost of production is hard to estimate, but it’s probably <US$3/kg of hydrogen if you used a traditional ~US5¢/kwh and assume “free” seawater. Capital costs are also modest with an electrolysis plant costing less than its renewable power source (EIA quotes a ~US$300/kw capital cost).

Once you have produced green hydrogen that’s only half the issue, as you then have to store it. At room temperature it is a low density gas which means a low energy per unit volume. Or 1kg of hydrogen takes up 11m3, which is why storage of hydrogen as a liquid is ultimately preferred but requires cryogenic temperatures (due to hydrogen’s low boiling temperature). Therefore, work is also focussing on materials-based storage solutions for hydrogen. This comes with its own challenges such as the energy density of the materials and release of hydrogen on demand.

So, the rise of low-cost electricity from renewables raises the opportunity to look at hydrogen as a potential source of transportable green power. However, whilst attractive there are some hurdles to overcome.

Here part of the opportunity with green hydrogen is its ability to play a key role in the production of green ammonia. This is a whole new topic, but it is fascinating as a teaser to see that three major companies (including Fortescue Metals) are vying for the opportunity to develop green ammonia plants at Bell Bay in Tasmania, most known for its aluminium smelter.

As aluminium is in part considered to be the export of “stranded” power, can hydrogen overtake that role in coming decades?

David Llewellyn-Smith


  1. Australia’s “green” hydrogen initiatives, announced last year use VIC coal.
    It’s the old coal gassification process to carbon monoxide (CO)
    CO + H2O -> CO2 + H2
    nothing green about it, except for the dull modern press.

  2. Hydrogen is a very tricky fuel for power. I can see it making its way into industrial applications, but for car, trucks, etc. it’s just way too dangerous and has a terribly low power density regardless of which way you come up with to store it (all current and proposed techs, anyway).

    • +1
      I can’t ever see hydrogen, green or otherwise, making it’s way into household stoves and vehicles. Can’t compete with solar + battery. Steel plants and export commodity, different story.

    • rob barrattMEMBER

      Too Right
      I did a Physics & Chemistry degree and I’ve seen that stuff going off. You wouldn’t want to be there……. It is of course odourless so a nice gas leak might well not be noticed until you apply the match!

  3. If all you have is seawater, then it has to be desalinated prior to electrolysis, which is again, an energy intensive step. The round trip of energy required to make H2 and then turn it back into electricity yields 25%, that is to say, if you start with 100 units of energy, make H2 and put it through a fuel cell, you get 25 units back.
    Hydrogen is difficult to store. It is a small molecule that leaks out of pipes. It is also a strong reducing agent that makes steel brittle over time, so materials handling issues are significant.
    One of the best innovations is the use of metal hydrides to effectively adsorb H2, much like the way methane is adsorbed into coal.
    Croud called Lavo seem to have cracked the technology. https://lavo.com.au/

    • Are you sure the seawater needs to be desalinated prior to electrolysis?

      As a water engineer, I can see a multitude of reasons why only pre-screening would be required; the electricity will probably deal with everything else.

      • The Stanford dudes are trying it https://news.stanford.edu/2019/03/18/new-way-generate-hydrogen-fuel-seawater/
        The problem appears to be corrosion of the anode. Promising technology, but like all of these projects it will drag in zillions of dollars to get to increasingly bigger pilots that still aren’t commercial in scale. However, it’s a start.

        The problem (and cost) of infrastructure for hydrogen trains remains the elephant in the room, of course. Ammonia won’t be the answer for effective round-trip energy efficiency.

      • I was repeating what I read about a project proposed for the Pilbara that involved desal up front.
        The project proposal seemed to be designed primarily to gain a massive grant for what appeared to be a carpetbaggers wet dram

      • Chlor-Alkali plants which produce chiefly chlorine and sodium hydroxide (lye) with a bit of hydrogen also work by electrolysing saltwater. They don’t use seawater though because it contains other salts (magnesium, calcium, potassium) that first have to be separated out, leaving just the sodium chloride.
        All this “green hydrogen” stuff is just bunk. Even at the most optimistic cost projections of $1/kg, when you run through the physics/maths it’s only going to be viable against gas prices of >$20/GJ

        • I agree with you, but this is Australia – there are numerous examples of logic-defying investment opportunities. When Mike Cannon Brookes, Twiggy Forest and our beloved Government are all looking at the same thing with unnerving enthusiasm, you know the game is already rigged and we’re already too late.

          The biggest disappointment about all this is the multi-year distraction from something that might actually be worthwhile (which is not a cue for other “fine on paper, not in practice” ideas like small-scale nuclear).

  4. Households and Cars will go battery (with or without solar charging) long before they adopt Hydrogen + Fuel Cell.

    Heavy Industry is a different matter, but it is rather naïve to assume that our Australian solar advantage will somehow out weigh our Industrial disadvantage over the next 50 years…(especially if the last 50 years provide any indication of our future direction)

    Mining and other remote power applications. Yes why not use Electrolysis to generate Hydrogen and store the Hydrogen locally (Methane and Ammonia are two of the better ways..but that’s just my opinion) Metal Hydrides are interesting technology but not one that I really understand (marketting info for Lavo lacks required data to understand round trip energy consumption, typically for Metal Hydride Hydrogen absorption happens at high pressure and Hydrogen release happens at high Temperature) Exactly what temp / pressure has a huge impact on the system efficiency…
    Another item missing from the Lavo blurb is poisoning of the Hydride lattice with other atoms / molecules.

        • Hahahaha. You forgot driverless cars.

          The entire thing is hogwash – our glorious government hellbent on burning FFs and using any and every strawman BS to justify it.

          Footnote: So-called ‘ renewable’ solar is also wishful thinking, requiring FFs to make, transport, install, replace and recycle; they also can’t be scaled up in time to replace the energy density, function and convenience off FFs)


          Moreover, as the energetic cost of obtaining FFs and other essential resources like lithium, cobalt etc is relentlessly rising while exploration and new discoveries decline year on year, there simply won’t be either sufficient FFs or resources to transition to so-called renewables.

          “This has always meant that the end of fossil-fuel-powered economic growth wasn’t going to be a matter of “running out of” oil, gas or coal, but of encountering rising costs (ECoEs) which erode the economic value of each unit of energy accessed. Cost and volume parameters are interconnected, of course, so that rising costs must inevitably, in due course, result in decreasing volumes.”

          Denial is a potent and almost universal human characteristic.

    • The thing to remember about mining is that it is almost always associated with a massive hole in the ground.
      This happens to be exactly what you need to implement your own Mini Pumped Hydro scheme.
      Even a very simple Pumped Hydro has no problem generating 50 to 60% round trip efficiency, and I’m told over 80% is achievable for a well designed system.
      There are very few Hydrogen storage systems that even try to achieve round trip efficiencies of greater than 40%., so small scale pumped hydro has this beat hands down. you just need around 100m elevation difference and say 1ML of water storage capacity top and bottom and you’ve got the makings of a serious high efficiency high capacity electricity storage system, that will run for the next 25 years with minimal maintenance and upkeep costs.

      • Yep the total Energy In vs Energy Out equation for Electric cars is far worse than simply continuing with ICE power but fortunately the Fuel is burned elsewhere so our city dwelling eco warriors can rejoice because they now have clean air.
        It’s all totally F’ed up from an physics/ energy perspective but at the same time it’s a slam dunk from a social perspective and there’s a lot of money to be made, so wtf do I care about the energy equations…
        just give the customer what they think they want and count the money

  5. Sub $3/kg green H2? Where do I sign??? The Au National H2 Strategy and Bloomberg numbers I have seen are more like $8-11/kg LCOH. And the seawater will have to be treated/desalinated.

  6. 99% of hydrogen is not green, uses methane. The remainder requires electrolysis, and is (at best) 70% efficient with the power output matching energy input.

    But spin it as new and green, it is the woke thing to do…

    • Just like ‘renewables’ are neither green nor renewable – use FFs every step of the way, which is why carbon emissions rise each and every year.


Leave a reply

You must be logged in to post a comment. Log in now