Thanks for the study. Super interesting. So they used Grand Canary Island as a proof of concept for the study. The two proposed storage mechanisms were li-ion batteries and hydro. They propose 5.82GWh, which is the equivalent of 108,000 of the cheaper 54KWh Tesla batteries. Hydro works well there because of their 2,000m elevation over a short distance. Their daily energy production is around 17.5GWh, and their proposed storage solution appears sufficient given the variability in predicted wind.

It looks like a good use case for this location, but I'm not convinced this can be scaled to entire continents. Let's take Europe (because I'm familiar with the data in Europe). Much of the continent is very flat. Denmark, Southern Sweden, Netherlands, and Northern Germany, for example, cannot take advantage of hydro storage, and this comprised the largest storage component of the proposed solution. In fact, given the elevation requirements, hydro would comprise a much lower proportion of storage than batteries, if scaled across Europe.

This leads to the second problem. Even if we assumed all of Europe had as high an elevation gradient as the Grand Canaries, the power requirements are on a complete different scale. Using the same ratios, with 37% of storage coming from batteries, and 89% of daily storage required to smooth variance, Europe would require 106.8 million Tesla batteries. For reference, Tesla has only ever produced around three million batteries in its entire existence. In reality, Europe would require far more batteries than this, as hydro storage is not possible in many locations, and economical line transmission distances cap out at around 500km.

We need new battery technologies or other means of economical storage to make such a grid work in Europe. I suspect the numbers are similar in the U.S. Biomass and geothermal help close the gap, but not nearly enough.

For posterity, I'm not proposing that at present, renewables can't comprise an even larger share of the existing mix. I'm arguing that renewables cannot comprise the entire mix at present.