Power is consumed in the creation of corona, arcing or sparking.

The creation of corona results in ionisation of the atmosphere (to form o-zone and nitric acid) and emissions in the UV and blue channels. The ionisation of the atmosphere also results in molecular vibration which causes a "crackling" or "humming" sound.

Arcs and sparks need strong enough electric fields to overcome the resistance of the atmosphere between the terminal points.
Both arcs and sparks cause heating of the terminal points and the resisting materials between (usually the atmosphere), ionisation of the atmosphere along the path through which the discharge occurs results in UV emissions.

The power loss is determined by multiplying the voltage in the conductor by the integrated current density over the surface of the conductor.

Power lost = revenue lost.

$ ₤ € ¥ !!

The UV emissions and ionised atmosphere cause additional damages:

UV sensitive materials (i.e. polymers) are damaged.
Both O-zone and nitric acid is formed from ambient atmosphere, both are corosive, causing damage to ceramics and metals.
The "crackling"/ "humming" noise caused by the generation of corona or arcing can be distrubing to people in the vicinity.
Both corona and arcing causes radio interference "noise".