INGENIEUR
INGENIEUR
Do You Know?
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