Proposed tidal generation of 5% of UK's electricity...

[DamonHD]

http://www.theregister.co.uk/2007/10/01/green_plans_tidal/

I read through much of the SDC's report on this earlier, and it is very thorough in covering power, environmental, business, strategic, etc, parts of the puzzle.

Report available here (about 6MB):

http://www.sd-commission.org.uk/pages/tidal.html

The tidal barrage would generate ~17TWh/year out of ~380TWh/year total UK electricity consumption.

Rgds

Damon

[feral air]

Does barrage not mean what I think it means?..

"a concentrated artillery bombardment over a wide area.

* figurative a concentrated outpouring, as of questions or blows : she was not prepared for his barrage of questions | a barrage of 60-second television spots."

Maybe it doesn't have the negative connotation over there that it has here. I would've went with "expansive system"..except that's close to expensive...hmm...yeah, that fits.

They think tidal can provide 10% of the power they use but this one project will only provide 4%....they think. They admit to needing to do more research so that's good.

What I didn't see was any estimates of the power required to build it or any kind of rough plan (I didn't download the report - just skimmed the site). If it can provide 4% each year but uses that much over 3 years to build it (+some nongrid energy and lots of human resources) then payback is a while off. And if they have to demolish it too early because it negatively affects the wildlife then...woops...it was a waste or maybe just a break-even project.

I think this is one of those things where they need to let it stew for a good long while. Maybe the "best" solution will come up from behind and smack 'em in the head. Kind of like when you're coding and you hit some insurmountable problem, leave it sit over night and the next morning (or even days later) the solution becomes obvious.

My state has been talking about tidal energy too...I wonder what kind of system they're thinking of when they say tidal though.

[DamonHD]

Hi,

The exact version of the project the report writers favour can probably provide 4.4% of UK electricity needs, out of a total of probably 10% of UK electricity in total from tidal power around the UK's shoreline.  Some of the rest of that that is currently less practical because of UK grid constraints or the need for less proven (tidal stream) extraction technologies.

I think that the construction energy (CO2 cost) compared to a planned lifetime of ~120 years is so low that it's all recouped within 5 or 6 months IIRC.

This project has been brewing for decades, BTW.

Rgds

Damon

[ghurd]

Payback will be faster the next time crude goes up?

G-

[feral air]

There's no way you can recoup that kind of investment in 5 or 6 months. 5 or 6 years I can believe.

120 years is a long time so even if you have exceptionally high maintenance/replacement costs, payback should be pretty easy...even if 20 of those years is paying for the energy used to build and maintain the project you've still got 100 years where the power is basically free.

But, it all hinges on the wild life. If they screw up the habitats and the project tanks because of it then it may never reach payback. That's my main concern.

[DamonHD]

Recouping the energy investment in building the barrage is ~6 months IIRC: it will be extracting an average of ~50GWh energy per day when functional.

But I may have misread of course.  I'll try and re-read the relevant bit.

The financial payback is much longer.

Rgds

Damon

[feral air]

Sorry, yes, I was mixing the two...

The energy-cost should be paid back very quickly but then the actual energy cost is hard to calculate. How far down the chain do you go for each piece of the puzzle? Do you count all the energy used to make each bolt? Are you counting what it costs each person to drive into work at the bolt factory? At the concrete factory? How 'bout what it costs to flush the toilets at those places?

This is kind of the same problem organic farmers have been having here. If you used a tractor to plant the seed can you call what grows up organic if you never spray pesticides or anything else? Some would say that part of that process is not organic, you didn't hand-plant each seed. Even if you did hand-plant some people are bound to say that some of the things you eat (twinkies?) aren't organic so your crops aren't either....where's the line?

I tend to think that something close to the financial payback is the real energy cost - that way you've covered every base. It's hard to take everyone's profit out of the equation but I think financial payback is a lot closer to the real energy cost than any other random guess.

I dunno...should be pretty cool once it's running, anyway.

[feral air]

financial payback = financial cost

sorry

[richhagen]

I wonder how the debates went when they were trying to decide whether to build the Hoover Dam, or the Grand Cooley.  I know there was a bit of controversy and quite a few people were skeptical as to whether the projects were worth the efforts and effects.  I don't know what the life span of those projects will be, but I would bet it is safe to say that they paid for the resources used by now.  Tidal power is something that I don't know too much about, but based on a small operation in either Spain or Portugal that I read about it seems that once the infrastructure is in place, it could last a long time with proper maintenance, and is currently practical to implement.  Given the thirst for energy that appears to be growing, and the fact that for the British, it will keep their capital at home, I would think it is definately worth exploring.  When looking at the impact, it needs to be compared relative to the energy sources that it will be replacing, as basically all sources of energy entail changes to the environment.  Personally, I hope they build it.  Most of the great projects that have had the largest impact on the modern World started out as grand but controversial plans.  To quote the city planner Daniel H. Burnham - "Make no small plans - for they have no majic to stir men's souls."  We need to build the World in which we would like to live in the future.  Rich Hagen

[domwild]

Thanks for that. Just saw it on Australian TV. Great plan. Have to ask my friends where the river Severn is.

The West Australian government, though, much to their shame decided not to build a tidal power station in the Kimberley region of WA with its 30 foot tides and opted for diesel instead.

Regards,

[DamonHD]

West of England, below Wales (near the bottom).  The big gash you can see going in on the left.

Rgds

Damon

[finnsawyer]

A while back there was a spot on the tube about a pair of turbines placed in the river off of New York City to catch tidal power.  One failed as soon as they turned it on.  I haven't heard anything since.  The power was supposed to go to a grocery store, which had lost a lot of frozen food during a power failure and wanted to avoid another occurrence.

As far as the marine life is concerned, it is adapted to the tidal flow.  Taking power from the flow will change it.  So, marine life may be affected.  And won't those turbine blades tend to chop up the salmon?

[DamonHD]

I believe they've thought about the self-chopping fish issue, and it is mentioned in the report, but I don't remember what the solution was, if one was needed at all.  Maybe they just put a fish-finger plant down-stream?  B^>

If the blades turn slowly and you can put reasonable-size mesh on either side of the turbines, at worst you'd end up with a few mildy-contused prawns...  P^>

Rgds

Damon

[ghurd]

I saw a show about the NYC Gorlovs on Discovery Channel. I think they turn slow enough not to chop most fish (?).

The shaft bent first on the one that broke, because they didn't expect so much stress, IIRC.

G-

[Gary D]

 I also watched the tv. program on the New York turbines. They only had 1 hour between tides to place the unit. They have identified at least 100 other sites in the waters around the city to place them.

 The site for the tidal wave generators has quite a wealth of info. In a related article from that site, was another artical. It is strange that getting up to 20% electric generation isn't enough to satisfy the EU. Need to take into account auto's, coal heating, and such they(EU) said...

 The rocking barges may create more marine life in the area helping the birds... Barnicles(sp?) and such, may attract fish witch in turn could feed the birds... Just some dumb thoughts...

 

[wooferhound]

Chopping up the fish

would feed the birds

Offsetting the number

of Birds killed

by Wind Turbines