No amount of power used will every get a radio signal beyond the horizon
HF signals bounce off the ionosphere/troposphere all around the world and back again. How do you think the Titanic's SOS was heard over the horizon?
I can often talk to Ham operators in Australia on 50mhz (near TV Ch1) during the summer months using just 10 watts or less..
Propogation is possible via ionosphic bounces and sometimes troposhpheric ducting.
And in fact TV signals from CH1 (46 - 51mhz) did (and still do in the North Island) cause considerable interference in the bottom end of the 6m Ham band. The signals are/were received in Australia and other countries during the same summer periods.
Depending on the time of day and the atmospheric conditions it is easily possible to talk around the world on frequencies up to about 30mhz. Higher than that it becomes increasingly difficult but NZ Hams have (rarely) talked to Australian Hams on 1296mhz.