Eventually fossil fuels will decline to the point that renewables will have to replace them, and the electric grid become 100% renewable. One of the factors that will make this difficult is that 50 to 90% will need to come from wind and solar, and both wind and solar are seasonal. And so is geothermal, though the amount of power it does or could provide is so trivial that it doesn’t matter, except perhaps for local areas near geothermal hotspots that also have transmission lines.
What follows comes from: NREL. January 2016. Doubling Geothermal Generation Capacity by 2020: A Strategic Analysis. National Renewable Energy Laboratory. Technical Report NREL/TP-6A20-64925
Many geothermal power plants generate less power in the summer. There are several reasons, but the main one is that there is a smaller brine-ambient air temperature differential. [ Though evaporative cooling can help (though I wonder how much extra power this takes).]
Figure A1. Comparison of Nameplate to Net Summer Capacity, 1990-2013. Figure shows current discrepancy between installed nameplate capacity (design output of installed projects) to net summer capacity (net output of geothermal power available for sale during the summer). As of 2013, EIA survey data from geothermal generators shows that geothermal nameplate capacity was 3,765 MW in comparison to 2,607 MW reported net summer capacity. Sources: Energy Information Association (2015) Nameplate Capacity: Form 860 Generator Data, State Electricity Profiles (July 2015). Summer Capacity: Annual Energy Review (2015).
As you can see in figure 2 below, most geothermal power is found in the west, especially California.
Figure 2. Map of United States geothermal regions.
I do not think we will ever have a renewable grid because all the things that generate electricity are tied to OIL for their manufacture, for their maintenance & for raw materials, electricity is not “renewable”, it’s too tied to oil & NONrenewable resources.
As shown on the map, geothermal is very limited in location, where most of it exists, there are no people so we would need long transmissions lines & their losses to get that energy to where it’s needed, not very doable.
I do not see how it will ever be possible for those so called “renewables” to replace fossil resources when it comes to generating electricity.
Why can’t most people see this?
Electricity is tightly tied to OIL!
Everything that generates electricity is tied to OIL, everything used to manufacture electric generators is tied to, guess what? OIL, COAL & NATURAL GAS!
The end of oil also means the end of electricity & 90% of US.
Another thing most people are overlooking is that for every calorie of food we produce, it took at least 10 calories of OIL to produce it! Without oil, most of us won’t be eating.
Yes, we can produce a lot of food organically however we have so depleted our soils, so contaminated them with petrochemicals, that it will take years of work to make that soil productive, in the meantime, we starve.
Before we used OIL to support our cancerous GROWTH, only about 2 billion people at most, could be fed with organically grown food, it was all organic back then, after oil, it will be even fewer.
I haven’t yet found a way to eat electricity, it’s just too low in calories & too darn shocking!
Aside from that, it’s not “renewable”.