I think he was also counting on a boost from the solar wind.
the energy imparted to the earth via the solar wind is measured in Giga watts on https://www.swpc.noaa.gov/
and it seems to be the main factor behind lightning's charge.
Viziv along with Baylor are looking to utilize Tesla's global transmission of power. By calling it a Zenneck wave they think they've escaped the negative connotations of a 'crackpot'
http://vizivtechnologies.com/