‘Energy independent’ Uruguay runs on 100% renewables for four straight months
(theprogressplaybook.com)
You're right; 2/3 of worldwide energy is actually waste heat.
https://www.businessinsider.com/most-energy-still-comes-from-oil-2015-10
Here's the chart from 2007: Waste heat / losses are in the top right, although it doesn't show the transport sector losses which are higher than for coal generation.

What this means is that when we fully electrify all sectors, by using renewable energy such as wind and solar, our total energy generation capacity will only need to be about 1/3 to 1/4 of what we currently produce today to fulfill our current energy needs. That's huge.