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Old 2022-06-30, 02:19   #133
kriesel
 
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At 300m minimum elevation difference, and unobtainable perfect efficiency, that's around 1.2 million cubic meters per GW-hour stored in pumped hydro.
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Old 2022-06-30, 03:02   #134
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Quote:
Originally Posted by kriesel View Post
<snip>
Lake Mead / Hoover Dam output versus year shows a considerable decline in the past 20 years: https://upload.wikimedia.org/wikiped...e_2000.svg.png
Over long periods, reservoir filling with sediment from upstream erosion or debris is an issue, as are any declines in the water level.
Lake Powell is really low. https://strangesounds.org/2022/03/la...-the-west.html
This May 26 story makes for sobering reading. Lake Mead water level running well below predictions, could drop another 12 feet by fall
Quote:
(CNN) - Federal officials have a sobering forecast for the Colorado River Basin: Lake Mead, the nation's largest reservoir which serves millions of people in the Southwest, will likely drop another 12 feet by this fall.

It's far below what the outlooks were predicting as of last year.
The latest forecast from the US Bureau of Reclamation shows the reservoir plummeting from its current elevation of around 1049 feet above sea level to around 1037 feet by this September.
BTW, "dead pool" for Lake Mead is 895 feet.

I was living in Colorado during most of the recent drought.

Look up the Hayman Fire, the Waldo Canyon Fire, the East Troublesome Fire.

This is a long-term, slow-motion disaster.
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Old 2022-06-30, 03:15   #135
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Quote:
Originally Posted by Dr Sardonicus View Post
This May 26 story makes for sobering reading.
The engineering and planning for Hoover Dam and the ensuing lake were based upon false assumptions about the long term availability of water. The decades leading up to it were anomalously wet.
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Old 2022-06-30, 05:19   #136
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there are farming uses other than sheep grazing under solar. Those include cash crops and cattle grazing.
Not according to the Washington based solar developer that contacted me regarding leasing farmland who clearly stated sheep and beekeeping possible but no goats or cattle or cash cropping. Even the landowner is fenced out and can only enter the array ~once a year with advance scheduling and utility supervision. These guys don't mess around with mere roof size arrays, they're doing tens or hundreds of acres per array and tens of MW output rating; farm-size installations; installations involving multiple farms. Many installations, in multiple states.
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California is looking at putting solar over aqueducts. This would shade the water, causing less evaporation, lessening the need to draw more water from the source. It would also provide more power than would be required to lift the water at the pumping stations. The idea of using solar alongside of railroad tracks (in the land that is used strictly to provide a buffer) can provide power and infrastructure to power the trains.
Shading a reservoir or aqueduct sounds like good efficient combined use and water conserving.
A train derailment could be hell on a rail corridor panel array. There's a lot of real estate aside divided highways too, but semis running off the road into the median could do a number on panels located there, or SUVs off into the ditch also. A series connected array segment may be wired for hundreds of volts. So if there's a rollover crash, there's a ready ignition source for the leaking fuel. Could get interesting quick. Hence NEC rapid shutdown provisions. https://www.solarpowerworldonline.co...-solar-arrays/ Pretty tough to maintain utility-grade security separating panels and wiring from vehicles and people in such layouts though. The trend around here is to reduce things vehicles can collide with in the rights of way, not add them. A lot of money is spent removing trees from the rights of way.

I had to look up dead pool. Level at which no flow downstream can be made to occur. It's below the hydroelectric generation minimum level. https://theconversation.com/what-is-...xplains-182495

Last fiddled with by kriesel on 2022-06-30 at 05:57
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Old 2022-06-30, 05:57   #137
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Quote:
Originally Posted by kriesel View Post
Not according to the Washington based solar developer that contacted me regarding leasing farmland who clearly stated sheep and beekeeping possible but no goats or cattle or cash cropping. Even the landowner is fenced out and can only enter the array ~once a year with advance scheduling and utility supervision. These guys don't mess around with mere roof size arrays, they're doing tens or hundreds of acres per array and tens of MW output rating; farm-size installations.
https://www.goodnewsnetwork.org/agri...-boulder-farm/
https://nwdistrict.ifas.ufl.edu/phag...-solar-panels/
https://www.energy.gov/eere/solar/fa...de-going-solar
https://www.futurity.org/agrivoltaic...anels-2152772/
https://www.farms.com/news/friday-fe...ls-177323.aspx
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Old 2022-06-30, 06:09   #138
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Though not apparent at first, your links support my point:
"Cattle grazing is generally not compatible with PV facilities due to the risk of damage to modules" https://www.energy.gov/eere/solar/fa...de-going-solar
"I canโ€™t drive my tractor through or around solar modules" That means the current farm operator would be unable to continue to farm the same crops near or under the array. Economics require large diesel tractors and combines for hay, corn, soybeans, wheat, the common midwest US farm field crops.
Midwestern farmers own or rent several hundred acres each on average, requiring large mechanized agriculture. Equipment barely fits into sheds with 14 feet high doors, incompatible with the low clearance of 6-8' given in https://www.goodnewsnetwork.org/agri...-boulder-farm/
Not small scale gardening in the shade of panels, or employing armies of migrant workers to handle hundreds of acres with intensive amounts of hand labor per acre. That model may be well suited to other parts of the US, such as California.
Some crops need full sun for full yield; usual midwest dairy farm crops corn, beans, alfalfa, oats. My little garden was much more productive last year after some trees at medium distance were removed. This year after more removal, the rosebush which earlier appeared to be dying recovered nicely and produced a lot of blooms for its small size.
I've been gradually reducing the number of trees on my lot at the urging of my lawn service. The grass was dying out and moss and other shade species taking over, and bare spots opening up due to lack of light as the densely planted trees that came with the place became quite large. The Google satellite view used to be mostly tree canopy, garden and a bit of grass and garage roof.
I also note that the installed utility scale arrays in my area are fenced sole-purpose. And solar leases I've found available for reading online applying as far away as Florida were also sole-purpose. And that crops-in-the-shade is described as a research activity in some of your links.
It will be interesting to see how this plays out.
Somewhat dated, but the punch line in "Sustainable Energy Without the Hot Air" written by a British physicist is that to meet nation-sized energy appetites it requires nation-sized sustainable energy deployments. https://fire.pppl.gov/sustainability_mackay_red.pdf worth a read to grasp rough scale. He uses mostly the UK.
From a conference at which Archer McDaniels presented on ethanol fuel production, and from ancient personal farm history, it used to be that about 20% of a farm's productive acreage was for production of horse hay, fuel for farm draft animals, and ethanol production to fuel mechanized farm operations would be very similar. Ethanol from growing corn or biodiesel is liquid solar energy. I do not expect to see electric tractors in appreciable use in the next decade. Farm equipment is already shockingly expensive, without adding 12-hour-battery costs also.

Last fiddled with by kriesel on 2022-06-30 at 06:53
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Old 2022-06-30, 12:11   #139
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Quote:
Originally Posted by Uncwilly View Post
<snip>
Droughts are local.
<snip>
Depends of what you mean by "local."

You might want to look up the Drought Monitor map, updated every Thursday. Most of the western US is in drought, with about 20% in either "extreme" or "exceptional" drought.

Regarding Lake Mead,

The inlet for the hydroelectric turbines is at 950 feet.

The lowest outlet is at 895 feet.

When the level dropped below 1050 feet, the Southern Nevada Water Authority's first pumping station became inoperable. Their new low lake level pumping station was completed in 2020 and went into operation in April 2022. Some of its intakes are below the "dead pool" level of 895 feet.

Regarding wind turbines,

There are issues with "collocating" wind turbines on farms. In addition to the disruptions to farm operations during construction, there are the concrete foundations for the towers, and the towers themselves. What happens to them when the lease is up?

The tower's presence - from an aesthetic standpoint, also because of the shadow it casts - mitigates against having one at all close to a dwelling.

Another issue is "infrasound." This is sound at frequencies below the threshold of human hearing. It isn't counted in "dBA" measurements. The "A" stands for "audible." Infrasound isn't audible. You can't hear it, but you can feel it. And it can be very unpleasant. It can cause panic and make it difficult or impossible to sleep. The kind of rumbling caused by trains or heavy trucks rolling by, or by big pipe organs playing the low notes, are familiar man-made sources. Earthquakes, even very minor ones, can also generate infrasound.

Wind turbine companies will try to get nearby landowners to sign "Good Neighbor agreements." My advice would be to seek the assistance of legal counsel before signing, or just don't sign.
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Old 2022-06-30, 13:24   #140
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An example of regulations affecting wind energy installations is available at https://docs.legis.wisconsin.gov/cod...128.pdf#page=3. Siting restrictions can be fairly restrictive as to location in rural areas even for real estate parcels consisting of hundreds of acres.

Re infrasound: https://en.wikipedia.org/wiki/Infrasound
https://docs.wind-watch.org/Mansfiel...-vibration.pdf
It's also a concern in transportation design (vehicles of various sorts, and road surface texture). Having one's internal organs oscillated at a fraction of a Hertz to a few Hertz is distinctly unpleasant. A stationary structure close to resonance excited by nearby wind rotor wake could produce a similar effect.
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Old 2022-06-30, 14:42   #141
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I want to build a turbine for my lair that operates at the brown note.

Wind and solar are fantastic as energy sources, but terrible at reliability. We still end up with the storage problem. Where can all that abundant free unreliable energy be stored?

If I can't get the brown note working then I want nuclear. Millions of tiny (thorium?) reactors distributed all over, not one huge terrorism target.
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Old 2022-06-30, 14:56   #142
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Wind and solar are fantastic as energy sources, but terrible at reliability. We still end up with the storage problem. Where can all that abundant free unreliable energy be stored?
In a gravitational field.

Raise and lower an appropriate tonnage of rock.
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Old 2022-06-30, 15:00   #143
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Wind and solar are fantastic as energy sources, but terrible at reliability. We still end up with the storage problem. Where can all that abundant free unreliable energy be stored?
In molten salt.

Desalination of seawater is known for producing large quantities of salt. In La Palma the salt is the product and the water is released to the atmosphere. Elsewhere, the water is pumped ashore and the salt released to the sea, to the detriment of the local wildlife.

Why not use both components where water is a useful commodity, storing any excess energy in a cheap phase-change material?
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