Power transmission of the future¿microwaves or superconductors?

As the world need for electric power grows, so the need arises for new techniques of transmitting large amounts of power over great distances. In addition to extra-high-voltage a.c. and high-voltage d.c. transmission systems, two radically new techniques are the use of superconducting cables and the use of large circular waveguides. Although there are technological problems, it seems that waveguides could offer an economical alternative to other systems.