You know very well which source he's talking about.
And he said say near infinite, precisely to defend against obnoxious commenters.
Are you talking about nuclear?
Some estimate we're currently only at Kardashev 0.8, harnessing about 80% of what energy from the Sun hits the Earth, while others argue that this percentage is much lower.
Ideas are easy, implementation is hard.
Edit for clarity.
80% seems super high, unless by 'harnessing' you also mean things like 'the sun energy warms up the ocean allowing fish to live which we then consume for some% of the energy that sun sent'.
I'd be pretty surprised if efficiently used energy / energy hitting the earth from the sun was >20%.
The numbers I'm seeing are 174 petawatts hits Earth and the world uses 18 terawatts of energy.