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UK unveils plans for huge lagoon power plants stretching miles into the sea
- jacquesm 12y agoThat's very little head. Does anybody have the engineering data on these projects? Have they built a smaller installation to prove the concept? Head height is a major factor in hydro power installations.
- gus_massa 12y agoAlmost simultaneous discussion: https://news.ycombinator.com/item?id=9130893 https://news.ycombinator.com/item?id=9130893 (9 points, 3 hours ago, 2 comments) The link is: http://www.bbc.com/news/science-environment-31682529 http://www.bbc.com/news/science-environment-31682529 And chisb put a additional link to: http://www.tidallagoonswanseabay.com/proposal-overview-and-vision.aspx http://www.tidallagoonswanseabay.com/proposal-overview-and-v... They have a little more information.
- Brakenshire 12y agoThere are some technical details about flow rates and head height in section 4.8 (p. 85/88) of this document: http://tidallagoon.opendebate.co.uk/files/TidalLagoon/DCO_Application/6.2_4.PDF http://tidallagoon.opendebate.co.uk/files/TidalLagoon/DCO_Ap... One other thing I noticed upon briefly skimming is they're considering installing turbines which can also be used as pumps. I suppose in principle, at the cycle of the tide when the head is low and the plant isn't producing power, you could use the same facility as pumped storage. There's also a rather florid promotional video here, if anyone's interested: https://www.youtube.com/watch?v=mXEmHDQtXnw https://www.youtube.com/watch?v=mXEmHDQtXnw
- scoot 12y ago> Have they built a smaller installation to prove the concept? Tidal lagoon / barrage power generation is already a thing, so the concept is well proven. > Does anybody have the engineering data on these projects? This paper covers the maths: http://www.inference.phy.cam.ac.uk/sustainable/book/tex/Lagoons.pdf http://www.inference.phy.cam.ac.uk/sustainable/book/tex/Lago... (while also exploring ways to increase head above tidal range).
- shawabawa3 12y agoHere's the operating sequence: http://i.imgur.com/y9IJ5Ip.png http://i.imgur.com/y9IJ5Ip.png Looks like for most of the power generation phase the head will be about 5m. According to their paper generation is effective down to about 1.5m
- lucaspiller 12y agoThe plant in Somerset will be on the Severn Estuary, which has a tidal range of 15m: http://en.wikipedia.org/wiki/Severn_Estuary http://en.wikipedia.org/wiki/Severn_Estuary
- angusb 12y agoHere's a very readable quantitative discussion about tidal power generation in the UK: http://www.withouthotair.com/c14/page_81.shtml http://www.withouthotair.com/c14/page_81.shtml
- pablobaz 12y agoHere's a proof of concept built around 620AD. Obviously a bit different but this type of technology has been around a long time. http://www.archaeology.co.uk/articles/features/harnessing-the-tides-excavating-the-earliest-mills-in-ireland.htm http://www.archaeology.co.uk/articles/features/harnessing-th...
- pjc50 12y agoUK unveils plans to build tidal power plants. We've been planning things in the Severn Estuary my entire life and so far not lit a single lightbulb from it. As all the comments on the BBC story say: get on with it, build the thing, and tell us when it's done. (There are a few tidal-power-through-undersea-turbines schemes in operation off Scotland, I believe)
- arethuza 12y agoThere is a scheme just starting to be built in the Pentland Firth between Caithness and Orkney: http://www.meygen.com/ http://www.meygen.com/ I believe the first commercial tidal scheme of this type (effectively underwater windmills rather than a barrage) was in Northern Ireland: http://www.marineturbines.com/3/news/article/7/seagen__the_world_s_first_commercial_scale_tidal_energy_turbine_deployed_in_northern_ireland http://www.marineturbines.com/3/news/article/7/seagen__the_w...
- achamayou 12y agoThere's been one in Brittany since the mid-sixties: http://en.wikipedia.org/wiki/Rance_Tidal_Power_Station http://en.wikipedia.org/wiki/Rance_Tidal_Power_Station It works alright, but unless you have a very luckily shaped coastline, it doesn't scale all that well. It's also subject to silting in the long run, which isn't great for the yield, or the local eco-system.
- arethuza 12y agoThat's a barrage - like the scheme discussed in the original article. The NI and Pendland Firth schemes don't rely on a barrage but on the very strong tidal streams naturally found in those areas.
- achamayou 12y agoYes I know, I was responding to the OP mostly, since you'd already provided a reference to underwater turbine schemes.
- dandare 12y agoFYI tidal power plants are slowing down Earth's rotation. http://physics.stackexchange.com/questions/6400/are-tidal-power-plants-slowing-down-earths-rotation http://physics.stackexchange.com/questions/6400/are-tidal-po...
- deleted 12y ago[deleted]
- bjelkeman-again 12y agoThe movement of the oceans, and flexing in the earth crust, also slows down earth's rotation. But we are talking milliseconds per century. [1] So, tidal power plants are going to have a very small effect overall. http://en.wikipedia.org/wiki/Tidal_acceleration http://en.wikipedia.org/wiki/Tidal_acceleration
- PuffinBlue 12y agoThis article reads like it was written by an 11 year old. Or someone who does not speak English natively. Either that or, knowing how these things have been rolling aroud the planning and NIMBY protest camps for years, perhaps the author gave it precisely the right amount of effort and attention to detail it deserved.
- hanoz 12y agoWhat I don't understand about the idea is this. This stretch of water has one of the highest tidal ranges in the world, but this presumably is a matter of resonance, i.e the Bristol Channel and Severn Estuary just happen to be shaped in such a way that their natural resonant frequency is a close match with the driving force's twelve and a half hour odd period. But surely this means that the extra energy in the water, over and above places with lesser tides, is not something that can be tapped again and again each tide at any significant scale, it's a one time only bonus in its potential and kinetic energy which is gone after you extract its power through dampening. The ultimate non renewable energy, gone in half a day! Anyway, I'll be giving serious consideration to dragging my family out early to see a five star Severn Bore the weekend after next, it could be the last one ever.
- jbattle 12y agoThat would be true if it were a freely oscillating system, but since the tide is 'powered' by the moon I'd think the tidal cycle should keep going until the moon stops orbiting. (though I'm not 100% sure I understand how tides work)
- happyscrappy 12y agoHe is arguing, probably correctly, that the damping caused by energy extraction will cancel out the natural resonance and therefore not be repeatable.
- hanoz 12y agoI don't see that. Surely if you have two swings hanging from a swaying tree and one of them is swinging wildly because it's the right length to resonate with the moving branch above, you can't say hey this x kg tyre is rising and falling y cm every s seconds, lets harness that. It only has the same renewable energy as the other swing, plus a one time build up of energy that its taken to get it up that extra height.
- DanBC 12y agoBut the moon is providing an input. So, for your swing example, there is someone on one side giving it a push every pass.
- quokwok 12y ago"Tidal Lagoon Swansea Bay is thought to be seeking a guaranteed subsidised price of about £168 for every megawatt-hour (MWh) of electricity it generates over a 35-year period – almost four times the current market price of power." http://www.telegraph.co.uk/finance/newsbysector/energy/11426748/Swansea-Bay-tidal-lagoon-appalling-value-for-money-says-Citizens-Advice.html http://www.telegraph.co.uk/finance/newsbysector/energy/11426...
- Alphasite_ 12y agoI'd assume that 35 years of inflation needs to be factored in as well, at 2% that would half subsidy by that point. Also, there is an inherent cost to green power, if it was cheap power companies would flock to build them of their own accord, but of course they dont, so the government has to subside them.
- quokwok 12y agoIf something has negative externalities, the solution is to tax the externality. E.g. a carbon tax will raise the price of fossil-fuel energy, which will make some green energy projects worth building. That's it -- job done. Subsidising "good" projects is instead of taxing bad projects is the wrong way to do it, because the government has to evaluate every project proposal to figure out which projects should be subsidised. Whereas a carbon tax does it for you; all the government needs to figure out is the cost of carbon, and the market takes care of the rest.
- scottkduncan 12y agoTimestamp this and come back in three years because we are basically sitting on the tipping point of some clean energy sources (not the one in this article!) becoming cost competitive. Solar and wind are at grid parity in an increasing number of places (Deutsche Bank says 47 of 50 states by 2016) and innovations in financing will be able to pick up the slack if/when subsidies expire.
- 7952 12y agoPresumably the barrages will last >100 year and be able to generate power the entire time. In the long run it could be much cheaper.
- porker 12y agoHow are they going to stop the lagoon from silting up and becoming shallower, short of dredging it regularly?
- monk_e_boy 12y agoMultiple pools. When the silted one is empty at low tide, use the water from the other pools to wash the silt out.