On the sunniest windiest days when wind and solar is massively overproducing we can synthesize natural gas or hydrogen. That can be used to fill in the gaps for

On the sunniest windiest days when wind and solar is massively overproducing we can synthesize natural gas or hydrogen. That can be used to fill in the gaps for the last 1-3% of energy. The rountrip efficiency of this is shit (~40% compared to 90% for pumped storage or batteries) but the important thing is it's cheap to store a lot of it for a long time and straightforward to use a lot of it all at once during those rare dark, windless spells. For natgas we even already have the infrastructure. What's really startling is the cost of producing a kwh from stored syngas/hydrogen generated from solar and wind is similar to the cost of getting a kwh from a nuclear power plant. So, worst case storage + solar + wind ~= average case nuclear power.