large electric capacitors The line losses of direct current are up to ten times smaller but the trans former and circuitry technology at the end points is clearly more complex HVDC lines through the Skagerrak for instance have been reliably con necting the North European synchronous NORDEL grid with the synchronous grid of Continental Eu rope since 1977 In spite of such connections the European synchro nous grids are far from being a highly efficient su pergrid although respective initial concepts were developed even before the turn of the millennium In such a supergrid huge amounts of electricity could be hauled across longer distances or im ported for instance from North African countries with plenty of wind and sunshine An agile and efficient distribution of large power packages from renewable energies across nation al borders or continents would also alleviate fears of capacity bottlenecks due to so called dark doldrums because there s always a place in the world where the sun shines or the wind blows That s why supergrids would marginalize the re quirement for huge storage capacities and conven tional base load power plants according to energy expert Dr Ing Gregor Czisch In view of so many positive aspects the ques tion arises why a supergrid isn t crisscrossing our planet yet While regional supergrids could bring cleaner more efficient and more cost effective electric power systems their development is com plicated by a number of factors explains Jessica Lewis senior research analyst with Navigant Re search These include limited political will lack of harmonized standards complex authorization and permitting procedures for cross border transmis sion projects and a conventional view of energy security as a national imperative with individual countries reluctant to leave their supply security in the hands of others Initial supergrid threads have been connected Even so the number of individual high perfor mance power transmission lines for renewable en ergy keeps growing Offshore wind farms in the German North Sea deliver their electric power to the mainland via HVDC lines The largest HVDC un derground cable project in the world is to be im plemented along the German SuedLink corridor In the United States such a connection exists for wind power across a more than 1 000 kilometer 620 mile distance from Oklahoma to Tennessee In Brazil 600 kV flow through a 2 400 kilometer 1 500 mile long HVDC line and in the so called Champa Project in India it s 800 kV across 1 365 kilometers 850 miles The construction of HVDC lines beyond the magic 1 megavolt limit is pioneered by China which has been transmitting direct current with 1 1 mega volts from Changji to Guquan across 3 000 kilome ters 1 860 miles since 2019 with a loss rate of less than five percent across the entire distance For comparison only 380 kilometers pass through the German 3 phase AC grid Via the energy agen cy GEIDCO initiated by Beijing the country is plan ning to drive the construction of a world spanning energy grid by 2070 even across oceans Estimat ed costs a mammoth amount of 38 trillion U S dollars The enormous costs are no doubt another reason why the global supergrid is currently very large meshed The Chinese megaproject as a supergrid level is intended to interlink the continental transmission grids The cumbersome shipping of energy across the oceans on board of gas and petroleum tank ers could then become history and instead Saudi Arabian desert sun might heat the fishing lodges on the Aleutian Islands via electric power cables The author From his desk at home he can almost see Europe s two largest transmission towers in Hetlingen North Germany connecting North and Central Europe as part of a 380 kV 3 phase AC overhead power line intersection Electrical energy plays a central role in Dr Lorenz Steinke s life and even though his first solar pocket calculator from childhood days didn t always work reliably he s already looking forward to low cost photovoltaic power from Dubai 14

Vorschau Schaeffler tomorrow 02-2020 EN Seite 14
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