> how do we provide energy ...? Renewables might work - if people stopped having kids for a while
It seems like you haven't done the math. I have. You're ridiculously wrong.
US marketed energy consumption per capita is 9.5 kW (see https://en.wikipedia.org/wiki/List_of_countries_by_energy_co...). That's 9.5 square meters of sunlight. If we pessimistically assume that we can only site solar panels on land (29% of Earth's surface) and only 10% of that, and that we're only using the currently common 16%-efficient polysilicon photovoltaic panels (rather than, say, solar thermal collectors or multijunction cells), then we receive enough solar energy for 60 billion people at current US levels of consumption, according to units(1):
You have: circlearea(earthradius) * 1000 W/m^2 * 29% * 10% * 16% / 9.5 kW
You want: billion
* 62.281752
/ 0.016056067
That's about eight times Earth's current human population.
Is it too costly? Currently, photovoltaic modules cost about US$0.50 per watt (see http://www.solarserver.com/service/pvx-spot-market-price-ind...), so, for everyone to consume as much marketed energy as USAns, we're talking about an investment of about US$4800 per person, or about US$160 per person per year, assuming a 30-year lifespan for the panels, even if costs didn't drop further. That's only about 1.6% of the nominal world GDP of about US$10k per year per person (see https://en.wikipedia.org/wiki/List_of_countries_by_GDP_(nomi...).
And that's just solar photovoltaic. EGS (see https://en.wikipedia.org/wiki/Enhanced_geothermal_system) and oceanic lithium (see https://www.withouthotair.com/c24/page_172.shtml) are two other energy resources of similar magnitude to solar photovoltaic, but they're being developed more slowly — photovoltaic is practical today.
Your comment would have been reasonable ten years ago, when solar PV was still expensive. The facts have changed. When the facts change, I change my opinion. When are you going to change yours?