modules and inverters which have been in con stant decline now for years solar parks in sunny regions are becoming increasingly attractive Such a solar park is currently developing in the des ert state of Dubai where the production costs for one kilowatt hour from solar energy are supposed to drop to a mere 1 5 cents which is a fraction of what electricity from conventional power plants costs Consequently there d be plenty of good rea sons for creating global power transmission lines so that electric snowmobiles in the icy conditions of the Russian port city of Murmansk could be op erated with CO2 saving solar power from the des ert city of Manamah in the future High loss power transmission If it weren t for Q I L R Delta U the formula that causes electric utilities and operators of transmis sion grids headaches worldwide The formula ex presses how electric current on its way through copper and aluminum suff ers a voltage loss on every meter or yard it travels while dissipating energy usually in the form of heat to the en vironment To reduce these so called transmission losses the cross sections of the lines must be en larged or the current stepped up Today the so called transport level of the synchro nous grid of Continental Europe formerly known as the UCTE grid operates with 380 kV alternating cur rent Russia and Canada even transmit electric cur rent at levels of up to 750 kV with one to six percent of the transmitted energy being lost per one hun dred kilometers 62 miles The loss for instance increases when the line bundles heat up to 80 de grees centigrade 176 Fahrenheit under load or emit their typical crackling noise via so called co rona discharges on hot summer days The electri cal energy lost by buried cable transmission on the way to the consumer amounts to yet another fourth AC vs DC That s why direct current has been seeing a revival for some time now by means of so called high volt age direct current HVDC transmission lines for in stance in the case of connections to off shore wind farms or point to point connections across long distances That s where 3 phase AC technology reaches technical limits because its lines act like By Dr Lorenz Steinke The hope that increasing use of renewable ener gies and the related geographic proximity between their sources and consumers would diminish the importance of power grids was short lived Today we know that this has not happened Although photovoltaics solar wind and above all hydro power are by now contributing about one fourth to worldwide electricity production they re not lead ing to grid independence Regional self suffi cien cy remains a utopian idea even in the 21st century The opposite is true Only a connection with many other producers results in the requisite supply se curity delivered by the small scale roof top power plant or the wind turbine on a village fi eld Proximity to the consumer is not always an ad vantage either For instance photovoltaic cells in tropical regions harvest more than twice as much energy from sunlight as comparable systems in more moderate climatic zones north of the 40th parallel where the hunger for electricity in cities like New York Berlin Moscow and London is great er than elsewhere In interaction with prices for This is how the global mega power grid of the Chinese GEIDCO project is planned to span the globe 13 Global

Vorschau Schaeffler tomorrow 02-2020 EN Seite 13
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