The engineering behind the US Strategic Petroleum Reserve

I get somewhat annoyed when people blanket attack Whitehall (the UK Civil Service) universally i.e. the bureaucracy, yes they have problems but you don't run a country with 70 million people without some bureaucracy and ripping apart a system that has worked for centuries means throwing out a lot of good with the "bad".

Salt does not burn, unlike oil. It would be sufficient to store dry salt, and prepare the brine during the pumping. Still a lot of hassle, of course.

But in reality, storing all of that brine would be a massive undertaking on its own. The largest salt cavern is 37M barrels which equates to a circular pond that's 600m across and 20m deep. That's huge. And of course you don't want the brine seeping into the ground water so it needs a good liner. But I suppose you really don't need a pond that big, how often are we completely draining the cavern anyway? We're at half capacity right now and that's the lowest it's been in 50 years. Normally it's been much much higher. So you really don't need all that brine, just enough for the normal ebb and flow of the reserves, maybe like 10%. In the event the reserves get drained, divert some freshwater to compensate.

The explicit purpose of the SPR is to function as a lever to smooth temporary supply shocks. The US increasing oil output by a few percent in either direction wouldn't have made any difference to global disruption of oil markets from a major exporter to Europe starting a war and then getting sanctioned.

As the article points out fire is a real concern here, which is one of many reasons making salt caverns so appealing. But it’s also a major driver for distance between each above ground tank, you want to isolate risks so a single failure doesn’t propagate across the facility.

Storing it in underground salt caverns is more secure, not necessarily cheaper.

We're decades away from the point we could have even possibly built 100 miles squared of solar farm much less the batteries to store it and replacing all the uses of fossil fuel that aren't just electrical generators. Even if we snapped our fingers and magically replaced every extant car, plane, truck and train with an electric equivalent and had all the infrastructure there's still industrial uses of petroleum that would drive a desire for strategic reserves of the stuff.

  Fuel companies state that untreated fuel will remain usable for only one year, after which fuel contamination ("the diesel bug") begins to appear

Also, the SPR is a complex system made up of several locations where salt massifs have been drilled and hollowed out in the shape of highly specified storage caves.

There are requirements for pumping throughput for example, and some of the concerns regarding operational life and the dozens of partial drawdowns these caves have been subjected to, relate to them loosing the ability to quickly discharge oil.

In a word: it's complicated. I encourage looking up technical documentation online, super easy to find using 'filetype:pdf'. There are a lot of details involved in building, running, and assurances required from the SPR storage system.