[hacst]

In my mind the even bigger questions is whether it being "cheaper" will stay true once we actually try to scale the use of the technology. As in can we use this to actually produce most of our energy needs and still have the cost benefit?

I'm not an expert on energy production but a study I recently read on this topic for the German "Energiewende" over here did not sound so great [1]. In Germany the renewables we can scale are mostly Wind + PV. However according to the study their seasonal patterns combined with the demand curve seem to make it pretty much impossible to actually expand them meaningfully. Over the year you'll get peak production far outstripping demand (we've already seen negative prices in our markets with current installed capacity) and in the troughs you will need huge production from other energy sources (mostly old coal plants at this point). As these are seasonal patterns this means you would need to store TWh over many months to average that out and make new installed renewable capacity actually useful. The study did some back on the envelope calculations for various options for that but none seemed to come close to achieving that.

If that is true, system wide such nice looking renewable price calculations are preconditioned on a backup structure of conventional plants being on standby to fill in the throughs. As this is highly uneconomical for them the cost for that will still have to be paid by the system. At the same time due to the extreme variability prices will drop to zero during peak times (well...unless you have feed-in tarifs) making cheap production prices still be a loss.

I imagine the calculations might look much more favorable in other locales where demand is better correlated with renewable production but I would be surprised if Germany is the total exception here.

[1] http://www.hanswernersinn.de/dcs/2017%20Buffering%20Volatili...