PERMITS ISSUED TO STORE TEXAS WIND ENERGY IN GIANT UNDERGROUND SALT CAVE, TOO Meanwhile, in Tennessee Colony: As Fairway works on retrofitting some of those giant salt caves south of the Astrodome to store crude oil, a company called APEX says it has the permits all lined up to outfit a cavern in Anderson County’s Bethel Salt Dome to store some of Texas’s excessive wind energy. The plan, if the company gets the rest of the necessary funding, is to buy excess electricity from the grid to run an air compressor, pumping air into a salt chamber as deep as the Empire State Building is tall. That compressed air (with a boost from some natural gas combustion) would then be used to turn a turbine when needed. Energy analyst Paul Denham tells David Fehling that only a few spots in the US along the Gulf Coast have the kind of salt dome geology being put to work by the Bethel project (and by the only other major compressed air plants in the world, currently operating in Germany and Alabama); a few other companies, however, are now working on taking underground caverns out of the equation. [Houston Public Media; previously on Swamplot]
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Soooo… salt domes are already buoyant relative to the surrounding clay.
They cause the slip faults seen all around the Gulf Coast area.
Won’t hollowing one out and filling it with air make it even more of a balloon?
An Empire State Bldg sized sink-hole would swallow up a lot of terrain…
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Geologists and Engineers, discuss:
@movocelot: the weight of air increases as you compress it. Weigh an empty basketball and an inflated basketball. The inflated one is heavier.
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I’m not worried about the weight. Im worried about the massive ground farts when it leaks.
At a few thousand feet in depth salt is not buoyant relative to sedimentary rocks so it is happy where it is. Buoyancy is a bigger factor as you go deeper because salt density remains constant and sedimentary rock density increases with compaction.
I would be inclined to worry more about the cycles of pressurization/depressurization – what kind of stresses is that putting on the structure?
Geologist and Engineer response to Movocelot:
While there are some very shallow saltdomes, most of them are well below shallow surface soils, like clays. For the most part they are located below a cap rock layer formed from sedimentary rock. So not like a bubble waiting to float up through the (extremely high viscosity) surrounding clays. Even emptying a salt dome to create a cavern does not itself have any real buoyancy impact. Start putting preasurized air in the cavern and nothing will happen. Look at a scuba tank, the tank does weigh something, but the air inside should be more than buoyant enough, uncompressed to float a scuba tank. Compressed and it has no buoyancy.
There are a lot of fault types in the gulf coast, caused by a bunch of different things. The faulting caused by salt domes happened a long long time ago and as far as I remember from college, did not cause major regional faults, but rather smaller faults in the cap rock above them.
The larger issue with modern faulting is subsidence, which is significantly linked to groundwater extraction from drinking water aquifers.
And yes, we’ve all seen the TX Brine salt dome failure videos.