back to article Digital Realty wants to turn Irish datacenters into grid-stabilizing power jugglers

Datacenter biz Digital Realty is to let facilities in Ireland feed energy back to the electricity grid when needed, helping to smooth out variability in supply, cut CO2 emissions and provide an additional revenue stream. The global datacenter operator is working with energy management company Enel X on a project to allow its …

  1. Doctor Syntax Silver badge

    It certainly increases DC risk. If there's a power failure just after the UPS has been supporting the grid for a while there'll be little or nothing left for the DC. OTOH if the UPS is big enough to support that scenario then surely it's bigger than the DC requires as a UPS so why would they be installing extra capacity themselves to support the grid?

    The same consideration applies at a smaller scale to selling back power from an EV.

    1. John Robson Silver badge

      Because that extra capacity can be used to generate profit.

      Additionally with modern workloads, they can probably be offloaded to a different data centre.

      1. Doctor Syntax Silver badge

        Why not lower costs instead by speccing a smaller UPS? Alternatively by more capacity solely to sell energy back to the grid without risking the DC?

      2. cyberdemon Silver badge

        Not your average UPS

        When they say "UPS" I don't think they mean the sort that you could wedge into the bottom of a 19" rack..

        e.g. The Microsoft datacentre in Dublin, had 150MW of Diesel generators -in addition to- 170MW of open-cycle gas turbine. They probably had the standard rackmount battery UPSes too, but they only need to run long enough to spin up the gennies.

        I think the idea is that the limiting factor is the grid substation, and so having both gas turbines and Diesel means that if the grid supply gets really expensive, then they can make a few quid extra by running both Diesel and OCGT so they can continue to run their operations while simultaneously exporting power to the grid. The substation is always at max capacity, either importing or exporting power.

      3. Snowy Silver badge

        The colocation outfit has nine bit barns clustered around Dublin

        A colocation data center refers to a data center that enables you to rent out space for your own hardware. For example, instead of using your own on-prem space for your servers, cables, networking devices, and other computing equipment, you can rent out space in a data center.

        There is no other data centre to offload to unless your running some other hardware in them too.

      4. IGotOut Silver badge

        I'll put it in context.

        Our "Small" data centre had 5000+ servers when I left.

        It had 2 battery UPS rooms, each about the size of 3 bed house in the UK. These were then backed up by two generators. Think the size of a European spec articulated lorry.

        So it's perfection feasible to pull of say 50% of the stored power without to much risk.

        Why so big? When there was a major outage, we were running on the UPS for almost 36 hours. If either part failed, you had redundancy.

        1. UnknownUnknown

          So if you export half of that you have only 18 hours.

          Ask yourself … “Do I feel lucky?" Well, do ya, punk?”

    2. Dave 126 Silver badge

      @Dr Syntax

      I had the same thought. However, an older Reg article linked in this one offers a couple of clues.

      1, It appears lots of data centres upgraded from vented lead batteries to lithium ion, which resulted in some extra capacity and different use profiles regarding charge cycles.

      2, changes in electricity costs and the granularity with which it is billed. Daily peak prices can be ten times the lowest prices, so some data centres were already experimenting with running from UPS when electricity was at its most expensive.

      1. FILE_ID.DIZ

        The few datacenters that I'm familiar with (eg: have stuff in cages) use rotary UPS instead of batteries of any chemistry.

        Batteries have maintenance demands and can leak or off-gas hydrogen which burns basically clear if you don't have sensors to detect hydrogen buildup.

        The few data points that I have doesn't make a trend, but there seems to be plenty of datacenters which either fall over due to poor UPS maintenance and/or battery hold time wasn't as expected or the/a UPS might have been the cause or the chemical accelerant for a fire, like OVH in France.

        Edit: That's not to say that rotary UPSs also don't have maintenance. But at least you're not pitching tons of batteries every few years if you're not doing some type of wet battery that have life-spans that can reach 20 years, iirc.

  2. hedgie Bronze badge

    This isn't a unique idea. I have read about start-ups taking old EV batteries that may no longer be good for driving and "upcycling" them into arrays for energy storage, particularly for such variable sources such as wind and solar. I do not know how effective or practical such storage is, but it is at least an interesting idea.

    1. cyberdemon Silver badge

      Second-life batteries

      There was much hype about "second-life batteries" a few years ago, then there were a lot of fires, so much so that the National Energy Administration of China banned the practice.

      "There is no second-life for EV batteries" because if you continue to use them after some cells in the pack are dead, then it can be very dangerous.

      Cells/"supercells"/modules connected in series all take the same current. So if one supercell is "dead" (usually defined as having less than 50% design capacity) then the whole pack is "dead".

      (a "supercell" is a bunch of cells connected in parallel, usually by fusible links. They form essentially one big cell, the capacity of which goes down as the cells degrade and/or the links fuse if a cell "fails short")

      1. hedgie Bronze badge

        Re: Second-life batteries

        Good to know. Also rather sad to hear.

      2. John Robson Silver badge

        Re: Second-life batteries

        More realistically there is a second life, but the first life is so much longer than previously expected that the second life is somewhat restricted.

        The linked article suggests that there has been one fire at a second life station... one.

  3. MOH

    Data centers already account for over 20% of Ireland's electricity usage.

    Claiming they can help reduce CO2 by providing power from their UPS back to the grid is just greenwashing. It's power that wouldn't be consumed in the first place if they didn't exist.

    It's like offering to use your private jet to carry one Ryanair passenger with you to reduce their carbon cost

  4. Snowy Silver badge

    Rather small

    It is initially integrating 6 MW of its UPS capacity into the program.

    I assume that should be 6 MWh (MW is power rather than capacity).

    Given that at 5577 megawatts (MW).

    Not doing much in of itself but it could be a start.

    1. Red Ted

      Re: Rather small

      I did wonder about this too. 6MW is a fiddlingly small amount of power on a national power grid scale.

      On average the UK (note, not Ireland) uses about 33GW (33,000MW) of power (all the time).

      The power storage (Pump-Storage Hydro Electric) in North Wales is rated at 1.2GW (for about 6 hours, I think) and SSE are planning a new 1.5GW (for up to 10hrs) in Scotland.

      1. cyberdemon Silver badge

        Re: Rather small

        I note that Elexon (data viewable on have recently updated their data reporting to display the "negative" side of pumped hydro. It uses about 1GW all night to produce 2GW over a few hours in the evening.

        Previously it showed as zero while "charging", but was presumably included in the demand figure.

        It would be nice if they could also pull out batteries and Diesel from the "Other" category

        1. Snowy Silver badge

          Re: Rather small

          If we all moved to EVs and did other energy demanding jobs over night would there be enough energy to pump the water up during the night?

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