INGENIEUR
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Future Energy
By Pang Soo Mooi
Power Transmission : Rise of the “ SuperGrid ” - The Economist
Transmitting power over thousands of kilometres requires a different sort of technology from the AC now used to transmit it tens or hundreds of kilometres through local grids . 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 “ supergrid ”.
When electricity flows down a line as AC , energy travels as a wave . When it flows as direct current , there is no oscillation . Both works well , but the deciding factor in AC ’ s favour in the 19 th century was the transformer . This allows AC voltages to be increased after generation , for more efficient transmission over longish distances , and then decreased again at the other end of the line , to supply customers ’ homes and businesses . At the time , direct current had no such breakthrough .
Over transcontinental distances the balance of advantages shifts . As voltages go up , to push current farther , AC employs ( and thus wastes ) an ever-increasing amount of energy in the task of squeezing its alternations through the line . Direct current does not have this problem . Long distance DC electrical lines are also cheaper to build . In particular , the footprint of their pylons is smaller , because each DC cable can carry far more power than an equivalent AC cable .
Valuable though they are , transcontinental links like those in China , Brazil and India are not the only use for UHVDC . Electricity is not described as a “ current ” for nothing . It does behave quite a lot like a fluid – including fanning out through multiple channels if given the chance .
Medical Batteries : Dark Arts – The Economist
Since their invention two centuries ago , batteries have been made from many things . The first were of copper and zinc . Today , lithium is preferred for a lot of applications . Lead , nickel , silver and a host of other materials have also been used . Until recently though , no one had tried melanin , the pigment that darkens skin and protects it against ultraviolet light . But , as he reported at a meeting of the American Chemical Society in Philadelphia , Christopher Betinger of Carnegie Mellon University , in Pittsburgh , has now done just that . His purpose is to create a battery safe for use in the human body .
Melanin is not , at first sight , an obvious battery ingredient . It is complicated molecule composed of carbon , oxygen , nitrogen and hydrogen . To synthesise it on an industrial scale would surely require biotechnology rather than conventional chemistry . But it does have the ability to capture and release positively charged ions , known as cations . Batteries depend on the movement of ions , so this property is a good start . On top of that , being a normal ingredient of bodies , melanin is not toxic . This is in contrast to many conventional battery ingredients . If melanin were to leak out of an implanted medical device , it would simply be mopped up by enzymes .
Better Batteries : Tiny balls of fire - The Economist
A nanotechnological accident may lengthen battery lives .
Most scientific discoveries are the result of a deliberate experiment . A few , though , occur by chance . One such piece of serendipity has just happened to Wang Changan of Tsinhjua University in Beijing and Li Ju of the Massachusetts Institute
28 VOL 75 JULY-SEPTEMBER 2018