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Swansea Lagoon option for Sandymount??

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  • 09-05-2013 11:27am
    #1
    ted1
    Registered Users Posts: 23,424 ✭✭✭✭


    Just reading up on the Swansea tidal lagoon project and its quite intresting.

    http://www.tidallagoonswanseabay.com/

    they say it'll cost 14p kWh which isn't great but could it work for sandymount, so would the height of the wall cause an issue, with regards NIMBYS?

    also would the amount of silting that happens in the bay pose to much of a problem, or would the wall cause the currents into the liffey esturay to be to strong?


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    #2
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,966 Mod ✭✭✭✭Capt'n Midnight


    Captain Bligh (yes that one) designed the Bull wall to cope with silting in Dublin. The resulting Bull Island gives an idea of the scale of silting here.

    Swansea has a tidal range of between 4.5 and 8.4 meters. Dublin's is 1.9 to 3.4

    The idea of a lagoon sounds crazy to me compared with building a few miles away. They are getting 250Mw from 9.5Km of wall in an area with an 8.4m tidal range.

    So a quick look to confirm that and indeed
    A few miles away you have a 14m tidal range and a wall just twice as long will give you 6,500Mw That's peak demand on this Island.

    Also during neap tides it could be used for short term pumped storage / load balancing in a sorta use when it's available sorta way


    http://www.constructionenquirer.com/2013/05/09/engineering-giants-sign-up-to-25bn-severn-barrage-plan/
    Five major engineering and consultancy firms have been signed up to develop plans to build a £25bn renewable energy barrage across the Severn estuary.


    BTW that Swansea blurb - minimum energy loss through distribution is a red herring. The losses are I squared R so when running at 1/2rd of maximum power you have 1/4 the losses.

    Using an 800KV line losses can be as little as 3% over 1,000 Km at full power
    http://www.energy.siemens.com/br/en/power-transmission/hvdc/hvdc-ultra/


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    #3
    ted1
    Registered Users Posts: 23,424 ✭✭✭✭ted1


    looks like an intresting project, how soon before these displace wind as the RES of choice, your guranteed the tide comes in and out 2 a day, so it makes for more predicatble generation.

    where would be suitable in Ireland for such a scheme?


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    #4
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,966 Mod ✭✭✭✭Capt'n Midnight


    ted1 wrote: »
    looks like an intresting project, how soon before these displace wind as the RES of choice, your guranteed the tide comes in and out 2 a day, so it makes for more predicatble generation.

    where would be suitable in Ireland for such a scheme?
    They won't displace wind because wind is far cheaper. Also the power is predictable, including the prediction that you will get lower power during the lunar cycle.

    If it wasn't for the capital costs you could link one to pumped storage and have power on demand. But far cheaper to use a smart grid.


    The killer is the size of the turbines. If you have a tidal range of as little as 1.9m in Dublin then you can't use massive turbines. Also both wind and water turbines work best when faster so there is a minimum head needed to be economic. A water wheel might work on a low head but not as efficient and there is the slight problem of varying levels on both sides.


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