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SA power-to-gas pilot to trial long-term renewable storage option

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A project that will test whether South Australia’s excess solar and wind power can be used to produce cheap hydrogen, both as a means to supplement Australia’s gas supply, and as a long-term energy storage option, has been backed by the Australian Renewable Energy Agency.

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ARENA said on Tuesday that it had put $5 million in grant funding towards the development of a pilot “power-to-gas” plant to be installed at the Australian Gas Network’s Adelaide depot, designed by Wollongong based company AquaHydrex.

The technology at the centre of the trial – the result of years of collaborative research at the University of Wollongong and Monash University – will use renewable energy to power ultra-efficient and low cost electrolysis, splitting water molecules into hydrogen and oxygen.

The resulting hydrogen will then be injected into the South Australian gas grid in partnership with AGN, supplementing – and decarbonising – the existing natural gas supply.

“It turns out you can inject hydrogen into the gas main up to at least 10 per cent of the total gas in there, perhaps quite a bit higher without any modification,” ARENA chief Ivor Frischknecht said.

In this way, the Australian-first trial is also hoped to result in a form of long-term energy storage that will complement other forms, like batteries and pumped hydro.

“In the future we’re going to have a lot of excess renewable energy on very windy days, on very sunny days, and we’re looking for useful things to do with that energy,” Frischknecht said.

“You can easily store the hydrogen for days, weeks or even months and then run it through a gas peaking plant or use it to supply other types of services like heating hot water.

“A battery is really only good for seconds to hours of storage at very most, and pumped hydro you might be looking at hours through to days.”

In a seperate statement on Wednesday, energy minister Josh Frydenberg said the project was “a leap forward,” and away from existing methods of producing hydrogen that relied on fossil fuel derived electricity and other expensive materials.

“This new technology will harness renewable energy and utilise ultra-efficient and low cost electrolysis to produce hydrogen, providing a scalable and affordable energy storage option that integrates with our national gas infrastructure,” the a statement said.

“By supporting innovative new solutions like this the Turnbull Government’s investment in this trial will help deliver an affordable and reliable energy system as we transition to a lower emissions future.”

Of course, as Frischknecht himself has noted, this is not the only trial of its type going on in Australia – or the world – at the moment. As we reported earlier this week, Moreland Council and the Victorian State government have announced that $1 million will be spent to develop a commercial-scale hydrogen refueling station for garbage trucks that will be powered exclusively by renewable energy.

And in June, the South Australian government launched stage one of its Hydrogen Roadmap, providing $8.2 million over four years towards construction of a hydrogen production facility, refuelling station and a trial involving six hydrogen-fuelled buses.

“It’s certainly not a new idea,” Frischknecht said in comments on Tuesday. “The challenge is that it’s expensive. But we’re looking to a future where renewable energy at certain times of the day is going to be free or almost free,” he said.  

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  • Roderick Williams

    This is a good step, the trade-off between batteries and gas storage will vary depending on the local climate but reusing existing gas plants may be a capital efficient way to get extended backup for renewables.

    Germany has a national power to gas project, http://www.powertogas.info, aiming at 1GW capacity in 2020/2025 time scale. They plan to use their in country gas facilities to provide storage, I believe they have 100+ days of storage.

    The Passive House planning software already assumes P2G for seasonal storage of renewables.

  • Alastair Leith

    I’ve been big on the potential for power2gas to fill the remaining gaps where PHES, CST+thermal storage and chemical batteries lose economic viability or capacity for some years now and so this development is encouraging to see. Especially for winter weeks on the island SWIS network in WA where winter wind droughts are a regular enough occurrence. These other forms of energy storage or alternatively wind and solar overbuilt to cover low generation capacity factors for a week or two at a time just become incredibly expensive.

    However, injecting H2 into the fossil gas network, rather than just pairing a H2 electrolysis plant next to a new or existing jet derivative gas turbine doesn’t come without potential risks for the climate.

    One issue is that the fossil gas industry is making a big push to greenwash fossil gas with their ambition to inject up to 10% H2 into the grid, they’ve produced an expensive PR collateral around this aspiration and it will be used to attempt to neutralise efforts to close down the redundant gas network via fuel switching to more efficient and cleaner electrical energy alternatives.

    • Mike Westerman

      Gawd that sort of Greenwich puts them right up there with civilised debates on SSM and banks that didn’t realise crooks were banking with them!

  • Tom

    This will be interesting.

    My gut feeling is that hydrogen gas as energy storage will not take off, but I might be wrong.

    One problem with hydrogen is that it is very difficult to store it under pressure without it leaking. It’s such a small molecule that it can get through almost any seals, and through lots of containers that you wouldn’t think anything would get through. You don’t want this happening with an explosive gas.

    I’m sure it can be overcome, but at additional cost.

    The second problem is that, although it has about 3 times the energy density per kg that methane has, a hydrogen molecule is only 1/8th the mass of a methane molecule, meaning that hydrogen only has a third the energy density per litre. Effectively, at a given pressure, only half as much energy can be stored in the same cylinder.

    Doing sums as I write – 1 cubic metre of hydrogen has about 12MJ of energy. A combined cycle gas turbine needs about 6000MJ to produce 1MWh. So that’s 500 cubic metres of hydrogen per MWh.

    To store enough hydrogen for SA for one day you’d need around 40GWh, so 20 million cubic metres of hydrogen, or 100m X 100m X 2000m.

    Of course, this is at atmospheric pressure and temperature, and of course it would be compressed, but even if it was compressed to 100 atmospheres this would involve a cylinder with diameter 100m and height of 25m (approx). A cylinder this size would need really strong walls to store this much pressure – I’m not sure what the limits of engineering are.

    You can’t liquify hydrogen (well, you can, but it’s really difficult).

    Still, maybe there will be an economical way to store it, and if there is then we’re up for some interesting times ahead.

    • Mike Westerman

      Metal hydrides using Li and Mg were favorites at one stage for hydrogen cars but I’m not sure what the current status is. Also using acetone similarly to acetylene cylinders helps overcome pressure/leakage problems if weight isn’t an issue

    • Just_Chris

      It’s fantastic to see the debate opening up in this space and it is really refreshing to see someone with an open mind commenting. Just a few observations and opinions on your comment.

      Hydrogen is a small molecule but it is well understood and there are low cost solutions to it’s storage and transport. Town gas was used extensively in many countries including Australia. Town gas is essentially a mixture of CO and H2 and was readily pumped through pipe networks all over Sydney and London. The 10% number is pretty much, as I understand it, attainable today with existing infrastructure. If you look at the Leeds gate project from the UK they carry out detailed assessments looking at capacity of pipe networks and storage facilities they found that in required increase in pipe line capacity in Leeds was fairly minor essentially the gas network is completely over sized in most places. You are absolutely correct in saying you will store less energy in hydrogen but the question is do we require 120 days of storage, which is what the current gas network holds – or rather should hold. I assume since we had a period last year where gas turbines couldn’t turn on because of low pipeline pressure the storage in the network was pretty empty – why have gas in a pipe or water in a dam when you can have money in the bank. WRT storage if you are after an example of a really big gas cylinder check out the gas pipeline between Victoria and Tasmania – an 800km long cylinder that operates at up to 148 bar.

      You are absolutely correct about the differences between H2 and CH4 in terms of combustion and volumetric energy density. I believe the 10% limit is largely related to the devices attached to the network like gas boilers and gas turbines. The gas network delivers about the same amount of energy as the electricity network – considering we have 0% renewable energy content in that network right now I think we can safely say it will be many years before we have to worry about exceeding the 10% number. If we do get to that point we will have the ability to turn off more than 10% of the electricity demand in Australia instantly and leave it off for hours with no fear of pot lines freezing.

      As for thermal storage, I am also a massive fan, especially in the domestic property. Every home in Australia has a 5-10 kWh thermal battery sitting around not being used to balance the grid. It can even be charged at over 100% efficiency when a heat pump is used, they can be charged to over 100% if needed and operate well in a partial state of charge. Smart use of these batteries could allow for far higher penetration of distributed domestic solar PV way beyond where we are now.

    • Steve

      From memory, another of our universities has been working on efficient ways to bind hydrogen to carbon – synthetic natural gas if you like. Methane can be stored more easily with about ten percent reduction in round trip energy (again from memory). Reasonable trade off given the amount of Natural gas infrastructure out there. The other approach is to bind with nitrogen (ammonia).

      • Mike Westerman

        There was an Israeli developed system along these lines using
        CH4 + 2O2 CO2 and 2H2O with concentrating solar being used to reduce the CO2 mix in a closed loop. CSIRO also did work on this.

      • Alastair Leith

        ammonia does not have the fugitive emissions issue and is just as useful as a combustable fuel source I believe.

    • Alastair Leith

      Hydrogen produced from electrolysis can be converted to more stable gases with larger molecules, or even liquid fuels at room temperature for higher energy density, better for transportation and storage (but really, why transport at all if not necessary, produce it where you plan to burn it).

  • Caffined

    Good to develop alternative storage possiblities…
    But a bit premature to think there may be a surplus of solar and wind power in SA !