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The missing link: why Australia needs energy storage

In visiting Australia regularly for the last two decades I have never quite understood why greater value is not placed on the nation’s latent solar and nuclear energy assets. Perhaps it is because Australia…

Australia’s hydro energy storage systems are getting long in the tooth: maybe it’s time to look at liquid air. Michael Mazengarb

In visiting Australia regularly for the last two decades I have never quite understood why greater value is not placed on the nation’s latent solar and nuclear energy assets. Perhaps it is because Australia thinks there is a vital missing link: the ability to store energy.

With renewable sources such as wind, wave and solar, energy is often created in the wrong place at the wrong time, making it difficult to utilise. Australians aspire to use renewable resources but are thwarted by the practicalities of renewables’ use in future energy generation and supply systems.

In Australia, climate change legislation is driving decarbonisation. This will shift the energy provision and create new markets. The public mind however is on cost, accessibility and security of supply.

In the UK, the electricity generation mix and the opportunities are very different. In November the UK Chancellor announced that energy storage technology was critical to the future UK economy and will be worth £10B a year by 2050.

This value comes from understanding where the different energy storage technologies fit into the grid at generation, transmission and distribution. It’s not simply a matter of providing storage capacity. Governments have to determine how to configure a robust energy system to suit the changing energy mix and minimise the cost of transmission investment as the demand for electrical power grows.

Which way is the best way?

Different applications demand appropriate storage characteristics and a range of technologies are needed to suit the specific needs. Technologically speaking, energy can be stored in mechanical, electrical or chemical devices and in the form of heat. All are probably needed, but - apart from hydro-storage dams - Australia has few examples at a significant scale.

So what might energy storage mean for Australia?

It certainly should not mean simply filling the country with batteries for storing renewable energy.

There have been some extensive battery park trials for regional storage in China and in the US (Figures 1 and 2) and in other energy constrained countries (such as Chile), but this does not appear to be a widespread option suited for Australia.

Figure 1: Chinese energy storage.

Figure 2: US energy storage.

Conventional batteries of different types have their place, but society really needs an alternative. This is not only driven by realisation of the cost, resource wastefulness, environmental impact and scarcity associated with rare earths components, but also by a growing public misgiving about safety.

Battery-related safety incidents have been growing rapidly over the last few years, in vehicular and air transportation, computers, large scale battery parks and wind/solar on site storage locations.

A range of energy storage methods are currently available; most of these have been reviewed recently. Figure 3 shows a summary based upon the scale of power rating and the call down time, expressed here as a discharge time at rated power.

Figure 3: System power ratings

Liquid air a great alternative

As Figure 3 shows, there are alternatives to batteries. For example, in the UK there is a growing interest in the notion of cryogenic liquids. These are reported to be a cheaper and better way to use solar energy to drive compressors to compress air to liquid air (as cryogenic fluids).

Liquid air is potentially an energy vector in itself; vapourising the liquid using low grade waste heat makes for a very efficient system that then drives a generator.

The round-trip efficiency of these systems rivals batteries. These have now been demonstrated at a small scale with 350kW/2.5MWh scale for on-grid electrical storage and further developments to scale out to beyond 10MW are underway. Some 100MW+ systems with GWhs of storage are deliverable using existing supply chains and components. Some comparisons of estimated costs for comparative storage systems have been mooted (see Table 1).

Table 1: Costs of storage systems.

Such systems offer a means for low cost off-grid generation. This can smooth power requirements and provide security of supply by creating a national reserve.

Liquid air can also be used directly as a fuel. The first “cars that run on air” are currently being evaluated and are attracting significant attention. Australia, like the UK, has existing infrastructure to support early adoption. The technology is from a mature supply chain and components with proven long life whose costs are known.

Liquid air storage is at low or atmospheric pressure, resulting in low cost, above ground, safe bulk tanks. There is no fuel combustion risk. There are no geological or geographical constraints to location of stores or distribution pathways.

The energy density of liquid air compares favourably to other low-carbon competitors. There is great synergy with other industrial processes, including use of waste heat and provision of cold. And liquid air can be used as an energy vector to transport this stored energy around by road (as is currently done) or ship (as with LNG).

A major review of this opportunity is underway and may have profound application for Australia if it turns out that liquid air can be used as a fuel. Meanwhile the UK Energy and Climate Change Minister John Hayes believes that liquid air may offer some radical solution with real economic stimulus to the economy.

Putting a value on energy storage is difficult. The value lies in different places for different applications. Take solar: the business model has a feedstock (sun) that is free, which means arguments based purely on technical process efficiency and cross-comparisons to other processes are not germane. Rather, it’s the benefit that needs to be quantified.

Australia too will need to grasp these emerging concepts as new opportunities emerge to better utilise renewable energy and mitigate escalating infrastructure costs associated with energy supply and security. I am increasingly confident that the decarbonisation drivers may open up significant new economic opportunities ahead.

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25 Comments sorted by

  1. George Michaelson

    Person

    if only we had a large, established national power infrastructure spanning more than one state, based on reversible hydro pumping technology...

    gosh. word-search in this article doesn't mention 'snowy' once. so.. in saying '...apart from hydro storage...' aren't you kind-of inviting me to ask "what about the hydro storage we have" ? the snowy has some, and queensland has some too. I am not sure if Poatina is reversible but I'm not sure if Tasmania was on your radar as a net energy source either…

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    1. David Jones

      Engineer

      In reply to George Michaelson

      I have read numerous comparisons between grid scale storage systems and they all make incorrect assumptions about pumped hydro, based on existing schemes. Pumped hydro schemes have been around for more than 100 years and every single one of them is designed to provide about a day of storage at their rated generation because that is what makes sense when using them as a load levelling tool in conjuncion with baseload generators. However they do not have to be sized that way and one day of storage is not appropriate for renewables backup. If pumped hydro was based around very large dams and longer storage/discharge times it could provide storage at a cost of $10 to $100 per kWh not the $420 /kWh shown in the table. The Lake Eucumbene/Lake Blowering pair could provide more than 1000 GWh of storage at $10 per kWh.

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    2. Paul Cm

      logged in via email @gmail.com

      In reply to George Michaelson

      George, the following quote from the article may help explain the omissions you raise:

      "Different applications demand appropriate storage characteristics and a range of technologies are needed to suit the specific needs. ... All are probably needed, but – apart from hydro-storage dams – Australia has few examples at a significant scale."

      The way I read this article, isn't really about 'picking a winner' per se, it is a) recognising that all storage techs have useful capabilities, b) all storage techs may well be needed, and c) the lack of emphasis on some promising techs.

      Cheers, Paul

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    3. George Michaelson

      Person

      In reply to Jonathan Maddox

      It was, and they did! I got a reply just before the GBP 14m investment announcement of a commercial scale plant was announced.

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    4. George Michaelson

      Person

      In reply to Paul Cm

      No disagree Paul. My motivations were in the operations-research sense "which investment choices we can make *now* have lower costs *now* for higher benefits *now*" -which of course has to be set against "which investment choices *now* maximise return *later*" -I sensed an article which discussed technologies which feel like they have payback "later" and it irked me we had no cost:benefit view on the existing hydro and pumped storage investment we have "now"

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  2. Karsten Mohr

    Cat Herder

    Richard seems to have missed what is going on, on King Island. They now have 3 MW / 1.6 MWh storage (hybrid lead-acid battery with Ultracapacitor) in combination with wind and diesel generator to power the grid of the island. Ok the battery will only power the island for 45 minutes.

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  3. Paul Cm

    logged in via email @gmail.com

    Very good article, thanks for sharing Richard.

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  4. Eric Anderson

    Eternal Student

    Calculations for long-term storage with pumped hydro obviously need to take evaporation into consideration. I've also read some promising research about using liquid sodium as a heat sink. But all of these present significant engineering challenges.

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  5. ernest malley

    farmer

    The great advantage of pumed hydro as energy storage (NOTE that we are talking about <I>energy</I> storage and yet the default assumption always seems to revert to electricity storage, a very different matter) is that once established it is almost maintenance free (apart from the turbine/pump combos), thanks to that inexhaustible resource gravity.
    The Snowy Scheme self generates about 2/3 of the electricity it consumes to get water to the MIA.
    No pollution, disposal, resource depletion/scarcity as with battery farms or unknown technologies as with liquid salt, frozen air, Uncle Tom Cobley 'nall .

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    1. George Michaelson

      Person

      In reply to ernest malley

      having visited Poetina in Tasmania, and seen a generator being stripped down (the spanners to tighten the bolts were as big as me, and looked like giant mecanno set tools) the "apart from" is pretty big. The engineers said that pea-sized material which passed their filters hit the turbine blades with sufficient force to be a significant risk of damage.

      nothing is free. pumped storage is working against gravity and consumes energy. you have to have sufficient base load or unused load, to justify "wasting" it for a less-than-zero sum game to get *some* water back high, to be a battery to drop low again later. The efficiency is not high (I believe)

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    2. Jonathan Maddox
      Jonathan Maddox is a Friend of The Conversation.

      Software Engineer

      In reply to George Michaelson

      Certainly, storage comes at a cost. I've seen efficiency numbers from the high sixties up to 85% for round-trip efficiency in pumped hydroelectric storage. Batteries do better when new, but the capital cost is higher and for some battery chemistries both the efficiency and capacity both decrease as they age.

      Given that in some electric power markets, the spot price of power can go *negative* in times of low demand and/or high intermittent production, there is plenty of opportunity to profit from excess energy by storing it, either for times of peak demand when prices are high, or for other purposes altogether.

      http://dotyenergy.com/Economics/Econ_Stabilizing_RenewableGrid.htm

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  6. John Newlands

    tree changer

    The woes of the Boeing Dreamliner and Tesla electric car show we may have pushed cold battery technology to the limits. I hope the claimed efficiency of the cryogenic system doesn't depend on food freezing factories conveniently locating next door. We need to see a plant with 1 Gwh or 3.6 GJ of energy storage, equivalent to a sixth of a tonne of coal . To power a city on a windless night will require Gwh's of stored energy.

    In Germany and elsewhere they are trialling synthetic methane 'wind fuel' so wind in effect provides its own gas backup during lulls. I've read somewhere the cost of storage should add only 25% to generation costs. If that can't be achieved at Gwh scale then power will have to be generated in realtime when the sun doesn't shine and the wind doesn't blow. For low carbon that will have to be nuclear, something people have trouble accepting which is why emissions remain so high.

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    1. Alex Cannara

      logged in via Facebook

      In reply to John Newlands

      Don't know what Tesla's "woes" are, but I'll drive the 2 miles down to its HQ here and ask.
      ;]
      They're ramping up to 400 cars/mo on the new Model S, which is looking good, especially as Tesla also works with Solar City to deploy solar-powered charging stations around Calif. & the US.

      Boeing's woes are self inflicted -- the battery was not certified in time to fly, so they flew it anyway -- almost killiong a whole planeload of folks at Boston. The 787 uses production subcontracting to an extent…

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  7. Alex Cannara

    logged in via Facebook

    Storage is indeed our key need -- efficient, low environmental-impact, storage. Figure 2 is an example of what not to do (but with enough subsidy, we do lots of dumb things here).

    We already have plenty of energy storage for thousands of years, and solar is properly listed here as a wonderful source, now that solar PV efficiency is climbing beyond 200W/Sq meter.

    What's the other storage? Make a fist. Look at that fist and realize that the same volume of Uranium will run 1/3 of Australia…

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  8. Mark Lawson

    senior journalist at Australian Financial Review

    I have no doubt that it can be made to work, but none of the material makes any reference to costs. How expensive is this approach? Although it sounds simple in theory you will note from one of the links in the article that they have to get rid of both water vapor and CO2 in the air before liquifying it, so you are basically dealing with liquid nitrogen (with some oxygen). So not only do you have to have build a wind farm, but the associated plant to do all of this on a large enough scale to make a difference, and it would have to be a significant scale. And you might have to build separate plants close to the farms, which are supposed to spread over a large area.

    At least with pumped hydro the dams were there to begin with, mostly.

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    1. Felix MacNeill

      Environmental Manager

      In reply to Mark Lawson

      Fair question, Mark, but have you ever thouight to ask what the cost of not transforming our energy-generation system would be?

      You're very keen to detail the cost of new technologies, but remarkably willing to ignore the current and future costs of the existing system.

      any figures for the cost of developing effective renewable systems only make sense when weighed against the cost of business as usual - otherwise they're just numbers floating in the air: not meaning much and easy to take pot-shots at.

      By the way, how are sales of your little denialist tome from Connor Court going?

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    2. Mark Lawson

      senior journalist at Australian Financial Review

      In reply to Felix MacNeill

      Felix - it is always a pleasure to hear from you. The little denialist tome, as you put it - how entertaining - has a chapter on the costs and benefits of reducing emissions. You should read it. About the only person who could make any of it add up was Nicholas Stern by making extreme assumptions about future damage and then using a low discount rate for the time value of money. Oh yes, and Prof Garnaut managed to make it add up, although I'm fogged as to how he did it.He doesn 't seem to add up damages in the future then discount back. One grumpy greenie told me its at a certain point in the report. I don't suppose you can make yourself useful by pointing out the section by any chance??

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    3. Jonathan Maddox
      Jonathan Maddox is a Friend of The Conversation.

      Software Engineer

      In reply to Mark Lawson

      The volumes involved are not huge, and separation of component gases in air is frequently done cryogenically anyway (fractional distillation). The cryogenic air technology is not substantially different from that used in LNG facilities. By-the-by, there is significant recoverable energy from delivered liquid methane, so the energy used to condense and liquefy it in the first place need not generally go to waste.

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    4. Felix MacNeill

      Environmental Manager

      In reply to Mark Lawson

      Patronising as ever, Mark.

      I think I've wasted enough time on your persistent nonsense for one day.

      I don't suppose you were able to get John Howard to launch your book?

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    5. Mark Lawson

      senior journalist at Australian Financial Review

      In reply to Jonathan Maddox

      Jonathan - all good points, although I'd be happier accepting the part about the volumes involved not being large if there had been some proper evaluation in the article. When wind goes down it can do some for long periods.. or are we talking about helping with transition, so that other sources can kick in? Also, although it may be relatively simple from an engineering point of view, most of the cost in any of these systems, wind or conventional, is in depreciation of the plant. So here we're talking about a lot more plant. Needs more details.

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  9. Comment removed by moderator.