Comments: In addition to the previous posting:
1. Leakage currents at the overhead transmission lines and insulation quality at the underground transmission lines.
2. HVDC transmission lines need to have a certain minimum length to pay off.
3. Overhead transmission is very vulnerable to the weather conditions, e.g. strong wind, ice, heavy rains, lightnings, direct heat of sun, etc.
4. Overhead transmission is consuming very precious real estate; especially in more populated areas.
5. Transmission line overall efficiency when it comes to energy transmission over long distances.
6. Potential danger to human beings and animals due to stronger electromagnetic radiation, and dropped live conductors lying on the ground.
7. Etc.