A fossil fuel free economy powered entirely by wind and solar power would look nothing like the consumer economy many affluent people now enjoy, for the very simple reason the sun isn't always shining and the wind isn't always blowing, even over large areas covered by technologically feasible electric grids.
There would be days or weeks when there wasn't enough power available to do ordinary things like running an air conditioner or a washing machine.
Even with a massive expansion of expensive batteries and pumped storage hydroelectric, both of which have severe environmental impacts, there could never be enough storage to fill all the gaps between supply and demand, even with "smart" grids and electric appliances.
Typically natural gas is burned as "backup" power in most renewable energy schemes. Even in a fully built out renewable grid, one where adding more wind turbines and solar panels only creates a useless surplus of electricity, natural gas provides 40% to 50% of the total energy. That's not really backup power, nor is it enough of a reduction to "save the world."
There's more than enough natural gas in the ground to destroy the earth's natural environment as we know it. If everybody is using hybrid wind-solar-gas energy systems then the world's natural environment will be destroyed.
This is one of those cases where "better than nothing" is just as good as nothing. The end result is still the same. This world civilization still dies sooner, rather than later.
I've always compared the problem to smoking. To quit smoking, you quit smoking. If you have a pack a day habit and you cut down by vaping on your breaks at work you still haven't quit smoking. To quit fossil fuels you have to quit fossil fuels.
Unfortunately, as the human population approaches 8 billion people, I don't think we can feed or comfortably house everyone at a decent standard of living without concentrated energy sources.
I used to be an aggressive anti-nuclear activist. I've changed my mind.
Seeing wind turbines scarring hill tops and ocean vistas, or solar energy panels on previously undeveloped land (especially ecologically fragile deserts) does not give me the warm fuzzies. These things are utterly vile and useless. I'd rather live near a modern nuclear plant.
"Renewable energy" schemes in places like California, Germany, and Denmark are a failure. These places have increased their long term dependence on natural gas. It's so bad in Germany they are still mining coal and are making themselves more dependent on Russian natural gas which will probably have grave political and environmental consequences in the near future, if it hasn't already.
France embraced nuclear power and was able to close its last coal mine twenty years ago.
I live in California. 41% of my electricity is coming from natural gas as I write this. That's not reflecting any shortage of solar or wind power, but an unusually long streak of hot weather and the impact of drought on hydroelectric generation. It's already 90F in California's Central Valley, expected to be over 100F. The air conditioners are running and they are powered by gas.
On better days 85% of my electricity is "fossil fuel free," and that 15% reflects gas plants that are kept running to pick up the load in case of any unexpected drop-outs.
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