by Matt Johnson
One of the problems that has grappled electrical engineers over the last few decades is the long-distance transmission of power. As the shift towards renewable energy continues, we are finding more and more electricity being generated farther and farther away from consumers. With an unavoidable power loss directly related to transmission distances, engineers have found themselves in a tough situation. The Economist (2017) dives into one technology, ultra-high-voltage direct-current connectors, as a particularly promising solution. Electric power grids were standardized on alternating current (AC) in the late 1880s and 1890s, and have stayed that way ever since. Alternating current travels like a wave: the energy shimmies back and forth through a conducting medium. As the distances of transmission increase, it takes more and more energy to push this wave through. Inherently, the more energy you put in, the more that is lost. Direct current on the other hand is a steady flow of energy, there is no oscillation. Therefore, over transcontinental distances, direct current power lines are much more efficient. The power lines are cheaper to build, because a smaller wire can carry more power: reducing weight and cost. Whereas the transformers for AC are relatively cheap, the comparable thyristors for voltage conversion in DC are pricy; but these prices are justified by increased transmission efficiency, especially over long distances.
The US has found itself a laggard in the adoption of this new technology. China already has a handful built, and more under construction. Their biggest project is a power connector 3,400 Kilometers long. This line carries a behemoth of power equivalent to the average usage of Spain. European utilities also have plans for trans-European connectors: especially useful considering the hydroelectric opportunities present. As the transition towards green energy continues, UHVDC connectors will hopefully lead in the economic transmission of clean, cheap power.
Rise of the supergrid: Electricity now flows across continents, courtesy of direct current. (2017, January). The Economist. Retrieved from: http://www.economist.com