ENERGY distribution has come a long way since the early 20th century, when cities pumped pressurised fluids to homes and businesses to power pneumatic machines. Today, energy flows around entire countries in the form of electricity. The grids which carry it, made from thousands of kilometres of copper cable, are fundamental to modern life. But there is a new shift afoot. As countries try to add more renewable energy to the mix, a transmission system known as the supergrid is taking shape. What is a supergrid?
Renewable energy sources—solar, wind and hydroelectricity—are different from fossil fuels. Gas, coal and oil can be piped or trucked to convenient locations for burning. Typically, power plants are close enough to population centres that the resultant electricity is easy to distribute, but far enough away that most people don’t have to see or smell them. Renewables come with no such flexibility. Wind turbines must be built where there is wind, solar panels where there is sun. The largest pools of renewable energy tend to be the farthest from human population centres; long, high-capacity electricity cables are needed to transmit their power. Traditional electric grids use alternating current (AC). These require huge amounts of power to push energy across long distances. Even when demand for renewable electricity is relatively close by, it can overwhelm the AC grid as it travels between source and destination. An entirely separate network of high-capacity cables can take the pressure off the AC grid.