submarine cables (such as the interconnector between France and England).
It is already used to transmit electricity over 1000-km distances
in South Africa, China, America, Canada, Brazil, and Congo. A typical
500 kV line can transmit a power of 2 GW. A pair of HVDC lines in Brazil
transmits 6.3 GW.
HVDC is preferred over traditional high-voltage AC lines because less
physical hardware is needed, less land area is needed, and the power losses
of HVDC are smaller. The power losses on a 3500 km-long HVDC line, in-
cluding conversion from AC to DC and back, would be about 15%. A
further advantage of HVDC systems is that they help stabilize the electricity
networks to which they are connected.
In the DESERTEC plans, the prime areas to exploit are coastal areas,
because concentrating solar power stations that are near to the sea can
deliver desalinated water as a by-product – valuable for human use, and
Table 25.6 shows DESERTEC’s estimates of the potential power that