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40% of US electricity is now emissions-free
(arstechnica.com)
This is a most excellent place for technology news and articles.
Total demand is not constant, but you can represent total demand as a sum of a given constant demand plus variable demand. Say for instance the average demand varies from 200-350 kWh a year. You could run nuclear power plants to generate 200 kWh worth of electricity, and use solar/wind for the remaining 0-150 kWh demand. It would be fairly efficient to have nuclear provide a base load of some kind while solar and wind vary to meet the full demand.