Caution: overselling may damage your battery

In my energy numeracy primer I have suggested we think of power stations as factories for electricity. To illustrate, we can compare them to a popcorn factory: corn gets delivered, workers run the machines, popcorn comes out and is sold for a price which is affordable yet still high enough to cover the cost of corn, wages, operation/maintenance, debt, regulatory compliance, and so on. A thermal power station takes in fuel – coal, gas, uranium, etc – and makes voltage and current from high quality heat by spinning magnets really fast. For solar and wind power the fuel is of course free (nature delivers it) but it’s best to put these power stations/factories out where it’s sunniest and windiest.

The analogy is just as valid for energy storage, except the fuel is the same as the product. Electricity is transformed into gravitational or chemical potential energy, then changed back again. At the scale of a regional electricity grid – an industrial scale – the economics of a factory still roughly apply.

Here is a “microgrid scale” battery.


It is part of the massive US$179 million Pacific Northwest Smart Grid Demonstration Project. Racks of lithium ion cells are housed within an 8,000 square foot (approximately 740 m²) warehouse, and can supply 5 megawatts of power for one half of an hour. The facility cost US$23 million to install. The results were recently compiled, with impressive success of the networked supply control systems.

So, when proponents of avoiding the consideration of nuclear energy invoke the promise of sufficient storage to replace conventional fossil fuel “backup” for renewable wind and solar, is this what they specifically have in mind?

Well, the sort of nuclear energy technology we have in mind, when built, can generate considerably more than 5 MW for half an hour. The 622 MW PRISM power block will supply 311 megawatt hours (622 x 0.5) in that time. The battery facility, 5 x 0.5 = 2.5 MWh. To match this 1/48 of a day nuclear output, the battery must be expanded by 124 times. Hopefully, the economies of scale might help to reduce the price tag below $4 billion (Australian dollars at current exchange rates), although the useful lifetime of these lithium ion cells will be very short on grid timescales. It would also be pretty big (124 x 740 m²).


It would pretty much fill the entire grounds of the new Royal Adelaide Hospital.

But how expensive is that? Australia’s most recent proposed grid-scale storage project, the $282 million Genex Kidston pumped hydro facility west of Cairns will produce 330 MW for 5 hours on a full reservoir, i.e. 165 MWh in a half hour. A tenth of this capacity would equal $28.2 million – so it is clear why pumped hydro storage is universally recognised to be the cheapest form of storage! And just to be clear, Kidston is not even intended for storing intermittent renewable energy (despite some heavily insinuating it may be so).


The most up-to-date estimate for the first PRISM power block puts it around $8.3 billion. With a physical footprint comparable to a conventional nuclear plant and a sixty year design life (with years between outages, not 5 hours, or half an hour), there is little need to further labour the point. Storage technologies are cool, and have a part to play in our energy system, but invoking them to dismiss modern nuclear energy has to be the oversell of the decade. If we’re not replacing fossil fuels in our energy mix at the scale of PRISM, we’re not really decarbonising.


Further reading:

Do the Math: A Nation-Sized Battery

Do the Math: Pump Up the Storage

The Future of Energy: Will ‘Cheap as Dirt’ Batteries Transform the Grid?

Moore’s Law and battery technology: No dice & Why Moore’s Law Doesn’t Apply to Clean Energy Technologies

The Catch-22 of Energy Storage

Watt Clarity: Approaching 62 hours becalmed on the mainland – what would this mean for battery storage?

Utility Drive: What’s behind the 900% growth in energy storage in Q2 2015?

Oil Price: California Public Utilities Vote No On Energy Storage

Georgia Power’s 1 MW battery is underpinned by diverse conventional generators



10 thoughts on “Caution: overselling may damage your battery

  1. It may take several decades before the “we can do it with solar, wind and storage” brigade realise that it was not as simple as they thought. Meanwhile, they will waste many millions of dollars on technology which can’t deliver the quality of service we get from the existing coal and gas plants. Some of that brigade will continue to canvas against nuclear power for the rest of their lives even when they realise that their fantasy just isn’t working.

    Hopefully the big users of electricity in factories and large shopping centres will see the world differently. Particularly when power dropouts become more prevalent. They will resort to more diesel generators. So much for reducing GHG emissions. Solar and wind with storage solutions may eventually increase GHG emissions not reduce them.

  2. Battery enthusiast John Hewson is to be on a committee that will supposedly make SA carbon free in a few years. It’s a shame AEMO doesn’t think that’s likely with batteries
    The paper covers stationary batteries, EVs and switching gas appliances for electric. I hope we get a transcript of what AEMO says to the RC.

    Unusual that the Kidston pumped storage proposal is in NQ same as the Ergon Energy home battery trial. Do the maths but Kidston will store 1,665 Mwh while the Sunverge batteries each store 12 kwh or 0.012 Mwh. I note an off-gridder writing in Online Opinion says we need 5 days of battery storage. That’s a lot of batteries for SA to eliminate dispatchable power.

    • I don’t think I can get behind the idea of charging grid batteries during the day, then using that to charge my EV overnight (especially without wind like last night). Aren’t we meant to be getting *more* efficient??

      5 days? Multiply my example by 240. I suppose we could spread the batteries out over the city, but again – efficiency.

  3. It’s also possible that neither Kidston pumped hydro nor Townsville home leased batteries will prove economic. They getting grants and soft loans from ARENA and CEFC to reduce their capital costs. At one time it was suggested that bulk storage should cost no more than $50 per Mwh which seems currently unattainable. If batteries go the way of hydrogen, CCS, dry geothermal, wave power etc you have to wonder what straw they will clutch at next.

    • And if new pumped hydro arbitrage can’t turn a profit in the NEM, I dare not imagine the government support required by large scale batteries at 100 times the cost which would be made to operate even less economically.

  4. Grid-scale battery would essentially just look like a big hydro project.

    Right now though, we’re not using it effectively.

    Hydro, pumped or otherwise, is stored energy more then generated. The bulk of the capital costs in building hydro production are in making the reservoir. The site C dam up here in British Columbia puts just shy of 1 billion in costs for power generation compared to 1.8 in making the dam. To make this behave more like a battery simply install twice the generation capacity with the expectation that there will be a lot more downtime. Behaving as a battery a hydro project could behave as the gas-power backup for solar/wind projects, producing power when the wind isn’t blowing and the sun isn’t shining. It’ll also spool up faster then a gas plant can heat itself up.

    The trouble is of course, hydro is largely a tapped resource, and much of it is used for base-load purposes but I think that if nuclear could be invited to take on the base-load role hydro acting as battery could actually make wind/solar work on a large scale. This lets each power source take advantage of it’s unique properties. Hydro being the most flexible would take on the hardest task of filling in the gaps left by the intermittent solar/wind power and nuclear, which doesn’t much like getting switched on/off anyways, would provide base load.

  5. Pingback: Base load electricity | thstlewpg

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