Here The Economist explains how the supergrid could transform the energy landscape. With ultra-high-voltage direct-current electricity, grids can be connected to power generation facilities over long distances. This has broad implications for renewable power generation as well as fossil fuel powered generation.
THE winds of the Oklahoma panhandle have a bad reputation. In the 1930s they whipped its over-tilled topsoil up into the billowing black blizzards of the Dust Bowl. The winds drove people, Steinbeck’s dispossessed, away from their livelihoods and west, to California.
Today, the panhandle’s steady winds are a force for creation, not destruction. Wind turbines can generate electricity from them at rock-bottom prices. Unfortunately, the local electrical grid does not serve enough people to match this potential supply. The towns and cities which could use it are far away.
So Oklahoma’s wind electricity is to be exported. Later this year, lawsuits permitting, work will begin on a special cable, 1,100km (700 miles) long, between the panhandle and the western tip of Tennessee. There, it will connect with the Tennessee Valley Authority and its 9m electricity customers. The Plains and Eastern Line, as it is to be known, will carry 4,000MW. That is almost enough electricity to power Greater London. It will do so using direct current (DC), rather than the alternating current (AC) that electricity grids usually employ. And it will run at a higher voltage than such grids use—600,000 volts, rather than 400,000.This long-distance ultra-high-voltage direct-current (UHVDC) connector will be the first of its kind in America. But the problem it helps with is pressing everywhere. Fossil fuels can be carried to power stations far from mines and wells, if necessary, but where wind, solar and hydroelectric power are generated is not negotiable. And even though fossil fuels can be moved, doing so is not desirable. Coal, in particular, is costly to transport. It is better to burn it at the pithead and transport the electricity thus generated instead.
Transmitting power over thousands of kilometres, though, requires a different sort of technology from the AC now used to transmit it tens or hundreds of kilometres through local grids. And in China, Europe and Brazil, as well as in Oklahoma, a new kind of electrical infrastructure is being built to do this. Some refer to the results as DC “supergrids”.
Read more here.