[RiseofAsia]

Ann la .. China already invented ultra high capacity transformer for super long length transmissions 2k km sub sub the water 

Losses are not only on the transformer lah.
On land it is 8 to 15% power loss during transmission.
Let assume losses on land and sea are the same.

Different power is lost at different stages

1-2% of energy is lost during the step-up transformer from when the electricity is generated to when it is transmitted.

2-4% of energy is lost in the transmission lines

1-2% of energy is lost during the step-down of the transform from the transmission line to distribution.

4-6% of energy is lost during the distribution

The average loss of power between the power plant and consumers ranges between 8-15%.

Mostly losses are at the distribution area. In the Sea, more expensive to lay and maintain the cable.