Update on Bay Of Fundy Tidal Power

waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
Underwater turbine was trashed by extreme tidal currents in just 3 weeks.
www.thechronicleherald.ca/Front/1252613.html

Comments

  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: Update on Bay Of Fundy Tidal Power

    I wonder what type of engineer UNDERestimates the power by 30 times??? I hope it was in the data or someone should be out of a job...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • BB.BB. Super Moderators, Administrators Posts: 29,482 admin
    Re: Update on Bay Of Fundy Tidal Power

    Not to make excuses--but it is not as "big of mistake" as it would appear.

    Power goes with the cube of the velocity:
    • cube root (30) = 3.1x change in velocity
    And when dealing with "real life" flows, turbulence, non-uniform fields (i.e., sea beds)--A Factor of 2x is almost "the same" in the modeling/measuring/predicting of flows.

    A factor of 10x difference is a "night vs day" difference in Engineering Terms.

    So, being off by 3.1 in velocity should probably not be a "fire-able" offense in a completely new field.

    10x safety factors is standard for construction (difference between expected loads vs expected failure loads)...

    Could you imagine if the Engineer told the bosses/folks paying for the project to make it 30x stronger and to make the generator 30x larger "just in case"...:roll:

    Drawing power from nature (wind, water, etc.) requires serious over design... People talk about designing for 100 year storms, but they may happen anytime:
    In their worst form, they were known as "100-year storms": catastrophes that occurred once a century and caused devastating floods.

    And yet, in just the past four years, three times the Merrimack Valley and Southern New Hampshire have been hard-hit by storms that once came with interludes of decades between them.


    So, do we design for 500 year events? How about 600 year events:
    Inscriptions on up to 600 years old stone marker located near the coastal city of Kesennuma warn descendants:

    "Always be prepared for unexpected tsunamis. Choose life over your possessions and valuables."
    "If an earthquake comes, beware of tsunamis."
    "High dwellings are the peace and harmony of our descendants, remember the calamity of the great tsunamis. Do not build any homes below this point."

    We know that it probably would have reduced the losses of life and ongoing Nuclear Power Plant radioactive releases in Japan if people took the geological reports of Tsunamis seriously over the last decades...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: Update on Bay Of Fundy Tidal Power

    hi bill, yes I was aware of the 10X engineering rule and have seen it used frequently. In forestry applications for road building we always looked for the 100 year event, yet as you point out we are getting events that are well in excess of those...

    I guess I am just set back by the fact that the turbine failed is such a short time after being installed in a water-body ( Bay of Fundy) that is renowned for having one of, if not the greatest high - to- low tide variations in the world, everyday... ? Glad it wasn't my $$$.

    info from BC Hydro on the project.
    http://www.bchydro.com/news/articles/conservation/novascotia_power_turbine.html
    and another
    http://www.nspower.ca/en/home/environment/renewableenergy/tidal/projectoverview.aspx

    Eric
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • FrxddyFrxddy Solar Expert Posts: 113 ✭✭✭✭
    Re: Update on Bay Of Fundy Tidal Power

    It surprises me too. They built a small one & ran it for a while to do testing. One might think that water movement was a well understood phenomenon. Seems not to be the case! But, all in all, a good idea and a good test. I live just a half day's drive from that area. It is amazing how the tides there come & go with great speed. One particular beach has a stairway going down to the beach. Big warning signs and two clocks with signage: This is the time now: This is the time you must be OFF the beach.

    If you are at the waters edge when the tide starts coming in, you CAN NOT outrun it. If you take off at a full run when the tide touches your foot you will not make it 300 feet. You will be swimming.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Update on Bay Of Fundy Tidal Power
    Underwater turbine was trashed by extreme tidal currents in just 3 weeks.
    www.thechronicleherald.ca/Front/1252613.html
    This is the second tidal turbine to be destroyed there, isn't it?
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Update on Bay Of Fundy Tidal Power
    ggunn wrote: »
    This is the second tidal turbine to be destroyed there, isn't it?

    No, just an update on the same incident. Big wheels turn slowly :p
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