[foofie]

> But I can't help but think of one "technology" that could make a scheme like this MUCH more effective.

I think this is one of those things that drive home the point that there are fundamental differences between physics and engineering.

The article states that the thermal silos are heated with excess energy from the power grid. This alone tells you right from the start that efficiency is not the primary requirement.

Sand is inert, doesn't decompose or degrade, is readily available, is easy to work with, and has no moving parts. You can make it work in a silo, or digging a well to fill it with sand. In fact, geothermal heat pumps are already used extensively in residential buildings to regulate temperature. You just have to drill a hole in the ground that's deep enough, run a water pipe through it to heat/cool the water, and run that water through your building to heat/cool the environment. The nifty trick of Polar Night Energy is that they introduce the extra step of actively heating the thermal source with cheap energy supplied by the electrical power grid.

This sort of argument is like complaining that a Formula 1 car is far more efficient than a Volkswagen Golf. Yes it is,but that's a mute point.

[standardUser]

I can't endorse this perspective enough. The amount of energy storage we need is staggering and ever-growing. We've someone convinced ourselves that the 'baseline' is consuming with abandon millennia worth of stored energy and anything even slightly less responsive than that is too inconvenient. Given those parameters, we need any and all energy storage options and efficiency is not a priority. Tesla powerwalls were never going to power the world, but giant caverns full of sand might.

[btbuildem]

Excess energy from the power grid -- in times when renewables produce excess energy.

Otherwise, the heat to be stored comes as a byproduct of local industry. Something that would otherwise be vented out and not used.