I don't know who told you this. Can you point to any large city that is running on purely wind & solar right now? As far as I'm aware, there's not even a large regional city that has demonstrated this can work with current battery technology. I would be really happy to be wrong on this, but as of right now, it's not an option and we need to be realistic about that.

"The US Energy Information Administration (EIA) says nuclear power plants had a capacity factor of 92.6% in the US during 2022. This compares to 36.1% for wind energy and just 24.8% for solar photovoltaic technology. To a rough approximation, it takes three times as much wind capacity and four times as much solar to produce the same amount of electricity as a nuclear power plant over a given period. This is complicated by seasonality. Solar, for example, is particularly ineffective during the winter months when energy needs in the northern portion of the country are highest."

[0] https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...