Much of the variability in solar and wind is predictable, both long term (solar generation at night or during a given season is highly preditable) or near-term (weather forecasts give very good 72-hour estimates of both load and supply). Germany's experience, documented by the Fraunhoffer Institute, are an excellent example of this. There are occasions where per-MWh prices have spiked or fallen drastically, but those are both rare (2-3X annually, for a few hours), and are almost always instances where the forecasts were in error.
The means of dealing with this are to have:
1. Dispatchable load (rather than today's dispatchable supply): high-intensity uses which can be cycled rapidly or on schedule.
2. Storage. Pumped hydro and compressed air energy storage (CAES) are the two most likely options. Synfuels -- hydrogen or synthetic gas or liquid hydrocarbons created from surplus electrical supply, are the most likely options in my book.
3. Standby capacity. Biomass, dispatchable renewable supply (hydro, geothermal), and other fuel-driven capacity (preferably carbon-neutral) seem to be the best bets. I'm pretty bearish on battery solutions in general -- they may work for standby, but the volumes and costs required for long-term supply are enormous. Fuel cell tech might be slightly better.
Rare earths aren't significantly used in solar, and only slightly in wind.
Note that not shifting from fossil fuels isn't an option. Whether due to CO₂ emissions or fuel shortages, that'll have to happen sooner or later.
Nuclear's a possible bridge but faces major long-term obstacles. Most notably that it fails of itself to answer the liquid fuels demand (though, as with renewables, synfuels driven by nuclear generation are possible).
The means of dealing with this are to have:
1. Dispatchable load (rather than today's dispatchable supply): high-intensity uses which can be cycled rapidly or on schedule.
2. Storage. Pumped hydro and compressed air energy storage (CAES) are the two most likely options. Synfuels -- hydrogen or synthetic gas or liquid hydrocarbons created from surplus electrical supply, are the most likely options in my book.
3. Standby capacity. Biomass, dispatchable renewable supply (hydro, geothermal), and other fuel-driven capacity (preferably carbon-neutral) seem to be the best bets. I'm pretty bearish on battery solutions in general -- they may work for standby, but the volumes and costs required for long-term supply are enormous. Fuel cell tech might be slightly better.
Rare earths aren't significantly used in solar, and only slightly in wind.
Note that not shifting from fossil fuels isn't an option. Whether due to CO₂ emissions or fuel shortages, that'll have to happen sooner or later.
Nuclear's a possible bridge but faces major long-term obstacles. Most notably that it fails of itself to answer the liquid fuels demand (though, as with renewables, synfuels driven by nuclear generation are possible).