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Not sure which idea is the most ridiculous, and the most expensive.Quote:
Originally Posted by Bushmiller
Just had a look at a marine chart - Approaches to Newcastle. Twenty kilometres offshore the water depth is around 120 metres (~400 ft for fossils) and the bottom is "mud and sand". It would be quite an engineering challenge to erect a tower there, especially if it had to be cost effective.
as far as I know, the "fossil" preferred measure for sub[sea]surface depth was FATHOMS, so for this fossil, the marine chart for the Newcastle approaches would have represented the depth as 65 FATHOMS, which was then converted to 120 metres when the chart was metricated.Quote:
Originally Posted by GraemeCook
(The "mud and sand" observation of the bottom might date to when the depth was determined using a lead line with a hollow filled with tallow.)
but back, sort of, to the general thrust of this overall thread, if AMEO is bemoaning the dirth of new renewable investment, perhaps it represents "the market's" assessment that there's no money to be [currently] made by investing in new off-shore wind generation. Especially while coal remains the primary source of of reliable electricity generation.
a quick gander at this chart The distance visible to the horizon from different heights (totally-cuckoo.com) suggests that almost all of a wind turbine located 20 km offshore would be visible to a person standing on Merewether Beach.Quote:
Originally Posted by Bushmiller
(to save you opening the link, I've copied and pasted part of the table below.)
assuming that an off-shore wind turbine was sized at around 15 MW (one this size was slated for construction in 2022), the blade length would be in the order of 120 metres, so allowing say 15 metres clearance for the expected worst case swell, then another 25 metres to clear the worst case wave height -- and all these clearance estimates might be far too optimistic -- the actual generator would be sitting on top of a 160 metre tall (above sea level) mast.
all of the mast, bar the swell and wave height clearances, would be above the horizon for someone standing on Merewether Beach. with the whole structure potentially visible to a person standing on Nobbys Head.
(whether a person can see that far on a clear day is another matter)
Height (ft) Height (m) Distance (miles) Distance (km) 10 3.05 4.18 6.76 30 9.14 7.25 11.75 40 12.19 8.37 13.52 50 15.24 9.35 15.13 65 19.81 10.25 16.58 70 21.34 11.07 17.86 80 24.38 11.83 18.99 90 27.43 12.25 19.79 100 30.48 12.23 19.63 150 45.72 16.22 26.07 200 60.96 18.72 30.09 300 91.44 22.91 36.85 400 121.92 26.46 42.65 500 152.40 29.58 47.64 1000 304.80 32.41 52.14
IanQuote:
Originally Posted by ian
I think Spring and Autumn are bad times of the year for investors contemplating entry to the market. Demand is low and as I mentioned in an earlier post, rooftop solar is going close to supplying a good portion of that demand. In fact, it has been to the point where negative wholesale prices are evident from about 0730hrs in QLD and this is despite the staggered morning peak, courtesy of daylight saving.
What this means is that from 0730hrs through to around 1600hrs, give or take a few minutes solar farms and wind farms have to shut down. There is no money there for them. Unless an investor chooses to put some storage in place, which for the moment will be batteries, I don't really see where there is any viability for a new player.
Admittedly this will change as summer temperatures increase and the air conditioners start cranking up in anger, but that is not happening right now. As we see -$40 hit the AEMO dashboard you just know that is it for the solar and wind farms. Wind farms are in a slightly better position in that they can capture some of the nighttime money providing the wind blows. It is my impression, but I have no evidence to back up this statement, that wind is stronger during the day because of thermal circulation.
Regards
Paul
IanQuote:
Originally Posted by ian
I picked that figure of 20Km as an arbitrary figure. I am not sure of how far out the turbines in any proposal would be situated, although I imagine it would have to be of that order to minimise interference with shipping lanes.
It is for the moment a very vague proposal.
Offshore wind farm proposed for Hunter coast, Chris Bowen calls for community feedback - ABC News
I did find some information that said the overall height of an offshore wind turbine was 200m. This was I think for the latest and largest machines, which would equate at least to your 15MW example.
Regards
Paul
PaulQuote:
Originally Posted by Bushmiller
although your 20km might be arbitrary, the continental shelf drop-off is approximately 50 km off-shore so that would place an upper limit in how far off-shore the turbines could be located.
At 50km, the earth's curvature wouldn't "hide" the turbine blades, but would the sky be clear enough for anyone be able to see them?
However, the water depth would be a construction challenge -- constructing the required piers is one of the reasons there's not a four-lane bridge connection to Tasmania.
Me thinks it's more likely that the Minister is having a go at distracting the great unwashed.
Make an announcement, spend a few million $ on a study, and when it comes to the crunch the study will recommend that the "proposed wind turbines" be located relatively close to shore -- somewhere outside a State's 3 Nm limit (known as coastal waters and legally part of each state) but inside the Federal Govt's 12 Nm limit. If the turbines were to be located beyond 12 Nm from shore they would be in a legal grey area.
At 4 Nm, the turbines could be visually intrusive. But at least the operators wouldn't need to pay the landowner a "usage fee"
NB,
3 Nm is about 5.6 km
12 Nm is about 22.2 km
interesting that the early stage cost estimates for these two projects are in the same order of magnitude as for Snowy 2.0Quote:
Originally Posted by Bushmiller
or should that be Snowy 20 (billion $)
Remember that you need a large subsea power cable to connect to these offshore windfarms - every additional km off the coast adds a substantial cost. Where the cable comes ashore, that's when the real arguments start. To get the generated power to where it needs to be, overhead transmission is the only cost-effective option. Massive landowner opposition to that already in the case of SOTS (Star Of The South) project. Those who say "oh, just put it undergound" have no idea of the massive costs involved in doing so.
Ahhhh, that explains ALL the issues with the project - all down to a silly typo :DQuote:
Originally Posted by ian
Mr. BQuote:
Originally Posted by Mr Brush
There is a degree of precedent in that there is a pretty big cable over to Tassie already. So cable undersea to the shore and a short(ish) above ground connection to a substation and from there into the grid. All doable, until the objectors come out of the woodwork. I have a relation who thinks solar panels are an eyesore.
:shrug:
Regards
Paul
But would they do it again?Quote:
Originally Posted by Bushmiller
Another example is in New Zealand.Quote:
Originally Posted by Bushmiller
Do a little sailing around that glorious country, and you will find that there are quite a few high voltage cables running offshore, presumably as a cheaper or more stable option than building transmission towers in the Shaky Isles.
Just one teensy problem with the short(ish) above ground connection, and landholders are already up in arms about overhead transmission lines. Its a VERY long way to do this underground !Quote:
Originally Posted by Bushmiller
Attachment 531962
FFQuote:
Originally Posted by FenceFurniture
They have done it twice already. Once, then again when it broke. As to another brand newie...probably not to Tassie.
Regards
Paul
Mr.BQuote:
Originally Posted by Mr Brush
I think we may have our wires slightly crossed here :rolleyes:. I was referring to the project proposed off Newcastle. I think you are referencing a Victorian site.
However, the problems are fundamentally similar. The power does not have to return to the old power stations. It can tap into the grid wherever there is a suitable substation and transformer. Typically, the voltage is stepped up for long transmission lines to reduce losses. Conversely, if there is no suitable HV line existing (Say 330KV), we have a problem: A very expensive problem. In fact it has been just that issue that was problematical in the early days of renewables as the new companies expected transmission lines to be made available and were most put out when they realised they had to contribute to those facilities.
At Newcastle there would be suitable lines existing, but how easily they are accessible is another matter.
Regards
Paul