Dc Stewart

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since Jun 20, 2019
Retired gubmint scientist, devoting my Golden Years to coaxing 10 acres of forest into a haven for permaculture and Druidic lurking.
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Recent posts by Dc Stewart

Someone posting a picture of their spouse in 5... 4... 3... 2...  :)
1 day ago
Paul's bio should include background music from Deadpool 2, specifically the apocalyptic choral accompaniment to the final ultra-fight:

Fighting dirty!
Fighting dirty!
You can't stop him!
He's the Juggernaut!
You can't stop this motherf*cker!
Holy shit balls!
Oh, holy shit balls!
Oh, holy shit balls!
Are there dogs in the area? Metal edging is notorious for paw injury, especially if it goes between the toes.
2 weeks ago
Removing a lengthy stretch of asphalt can be a herculean task. On our previous property we replaced a worn out driveway. The asphalt was a standard 4-inch pour; the attached picture gives an idea of the scale of the removal process. The crew's dump truck made many trips that day.
3 weeks ago
Keep in mind that, in one of the many gif-movie internet spoofs of Lord of The Rings, when Boromir utters the famous line "one does not simply walk into Mordor", Frodo replies with the obvious and reasonable:

"Yes you do! You TOTALLY do!"
3 weeks ago
A problem with underground nests is that you don't know exactly what you're up against  (i.e., the size of the opposing army and the layout of their fortress) until the war is over. A nighttime assault gives you a temporary element of surprise, but within 10-20 seconds they're awake and boiling out -- half of them from that exit you didn't know about -- with a score to settle.
4 weeks ago
On a hot day like today I could definitely go for getting caught in the rain. Conversely, I AM into yoga and, except for the occasional mimosa, am not into champagne. I'd be okay with the whole "making love at midnight in the dunes" thing if it weren't for the sand trying to join the fun.
4 weeks ago

I understand is that even a Carrington event is not a global phenomenon

Hi Eric,

Technically, a magnetic storm is a worldwide event inasmuch as the entire magnetosphere is involved. However, you're correct that the effects of the storm can be very localized.

In general, the storm does damage by inducing sheets of current in the earth's crust. A regional effect is that the current density tends to increase at higher latitudes due to the higher magnetic activity in the auroral zones. Unfortunately, much of the industrialized world reaches into the high latitudes.

The induced currents are able to enter the power grid at the points where the grid is connected to the earth. In regions where the crust has low resistivity, the currents *may* stay put within the crust and not enter the grid. However, in regions of high crust resistivity, the grid offers an easier path to the currents thanks to the grounding points. So, another regional effect is introduced: a portion of the grid sitting above conductive bedrock may see a negligible amount of invading current while a neighboring portion sitting above resistive bedrock sees a huge amount. The picture below, from a USGS publication, illustrates the process.

This is where the power industry's interest in "risk maps" comes in. Over the past decade or two, the Space Weather and Geomag communities began combining data on regional crustal resistivity with historical and simulated data of magnetic storms to produce national maps showing how much induced current might be expected at different points of the grid for a given level of storm. The power industry then uses the maps to assess the vulnerability levels within the grid and come up with mitigation plans.

If a major collapse of the grid occurred, a limiting factor of the recovery would be simple human short-sightedness. Around 2005 I was told by an industry rep that full recovery might take decades because 1) the existing stock of replacement transformers is a tiny fraction of the many thousands that would be lost to meltdown and 2) worldwide there are only a handful of manufacturers of said transformers. I hope that The Powers That Be have addressed this issue since then.

1 month ago

I should probably shut up about the EMP as it is an extremely remote likelihood.

Hi Eric,
The possibility of a large-scale magnetic storm isn't too remote. In 2012, the Earth got lucky and was outside the path of a massive CME. The Space Weather and Geomagnetism communities later determined that, had it hit the Earth, it would likely have been a Carrington-level event. The power industry is increasingly aware of the danger and is steadily supporting development of mitigation strategies and geoelectric "risk maps" similar to risk maps for earthquake damage.

NOAA has an interesting slide show that summarizes the vulnerability of power grids and includes some photos of what storms like the 1989 "superstorm" and the 2003 "Halloween storm" can do to the huge transformers that the grid depends on. The conclusions rather casually mention that the 1989 storm packed about one-tenth of the punch of the Carrington event:

Geomagnetic Storms and the US Power Grid

1 month ago
We've somehow ended up at the overkill end of the electricity spectrum. Our property came with a 20kva diesel generator that had some mechanical issues and was so old that nursing it and finding parts would be a full-time job. It crapped out on the first winter power outage.

The smallest replacement we could find on short notice was a used (120 hours) 40kva tricked out with a load bank and acoustic weatherproof enclosure.  The installer had to stop in mid-installation to go get a bigger tractor -- the one he brought was big enough to move the old generator but waaay too tippy with the big kahunga on the forks. So far it's performed flawlessly for its weekly 20-minute exercise cycle and through power outages ranging from 4 to 16 hours. We estimate that, if we were frugal about power use, it could run non-stop for up to 10 days on its internal fuel tank, and non-stop for another three weeks on fuel transferred from the external tank that holds our heating oil.

Having 40kva available borders on the obscene, but it's nice to know that during a power failure we could bake a turkey while running space heaters and a blow dryer with maybe some laundry and arc-welding on the side. It's also reassuring when the lights go out to count "4... 3... 2... 1..." and hear that big 'ol John Deere engine spring into action.

1 month ago