Manhattan Contrarian by Francis Menton July 29, 2021
Yesterday’s post made the point that states or countries seeking to march toward 100% “renewable” electricity don’t seem to be able to get past about the 50% mark, no matter how many wind turbines and solar panels they build. The reason is that, in practical operation, due to what is called “intermittency,” no output is available from the solar and wind sources at many times of high demand; therefore, during those times, other sources must supply the juice. This practical problem is presented most starkly in California, where the “renewable” strategy is based almost entirely on solar panels, with only a very small wind component. Daily graphs published by the California Independent System Operator (CAISO) show a clear and obvious pattern, where the solar generation drops right to zero every evening just as the peak demand period kicks in from about 6 to 9 PM.
Commenter Sean thinks he has the answer: “Given the predictable daily power generation cycle of solar in sunny places like California and the predictable daily demand which peaks in the evening perhaps solar generators should be required to have electricity storage equivalent to the daily generation of their PV system.”
I thought it might be instructive to play out Sean’s idea to see just how much solar generation capacity and storage it would take to make a system out of just those two elements that would be sufficient to fulfill California’s current electricity requirements. Note: this is an exercise in arithmetic. It is not complicated arithmetic. There is nothing here that goes beyond what you learned in elementary school. On the other hand, few seem to be willing to undertake the effort to do these calculations, or to recognize the consequences.
We start with the current usage that must be supplied. Currently, the usage ranges between a low of around 30 GW and a high of around 40 GW over the course of a day. For purposes of this exercise, let’s assume an average usage of 35 GW. Multiply by 24, and we find as a rough estimate that the system must supply 840 GWH of electricity per day.
How much capacity of solar panels will we need to provide the 840 GWH? We’ll start with the very sunniest day of the year, June 21. California currently has about 14 GW of solar capacity. Go to those CAISO charts, and we find that on June 21, 2021, which apparently was a very sunny day, those 14 GW of solar panels produced at the rate of about 12 GW maximum from about 8 AM to 6 PM, about half that rate from 7-8 AM and 6-7 PM, and basically nothing the rest of the time. Optimistically, they produced about 140 GWH for the day (10 hrs x 12 GW plus 2 hrs x 6 GW plus a little more for the dawn and dusk hours). That means that to produce your 840 GWH of electricity on a sunny June 21, you will need 6 times the capacity of solar panels that you currently have, or 84 GW. When 7 PM comes, you’ll need enough energy in storage to get you through to the next morning at around 8 AM, when generation will again exceed usage. This is about 13-14 hrs at an average of 35 GW, or around 475 GWH of storage.
More:
https://www.manhattancontrarian.com/blog/2021-7-29-a-little-arithmetic-the-costs-of-non-fossil-fuel-back-up-for-solar-power
