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Overcoming Resistance with Super-powered Materials

Look! What’s that up there in the sky?! It’s a bird! No, it’s a plane! No, It’s Superman?!

Ok – not really. But some time soon there might be high temperature superconducting material up in the sky. Teams of scientists in the US and Europe are studying the incorporation of superconducting wire into wind turbines (in place of copper) which could increase the generation power from 2-3 megawatts to super-powered 10 megawatt generators.

Why does replacing copper with super material make such a difference? Resistance is at the heart of it all. The electrical resistance of the copper wire (or whatever conductive material you have selected) limits the amount of current that can flow through the coils. Electrical resistance opposes, disrupts, or slows down the flow of electric current therefore requiring more energy to move electrons (electricity) from point A to B. More energy required often also means higher costs. A true superconducting material has absolutely zero electrical resistance – meaning electrons flow freely and essentially – infinitely within specific current densities.

So, if superconductors are so great why aren’t they ubiquitous? One word. Temperature.

Remembering way (way) back to high school science class one may recall that the phenomenon of no, or extremely low, resistance occurs in some materials close to absolute zero. Let’s think of temperature as the villain in our super powered story – because absolute zero is REALLY cold (-273.15°C to be exact) – prohibitively so for commercial applications of superconductors.

But wait, just like how Clark Kent becomes Superman in a telephone booth, ordinary cuprate material can become superpowered when modified with yttrium (a hard to pronounce rare earth metal) to make YBCO which is probably the most common high temperature type II superconductor. Add the secret ingredient, freezing cold temperatures, and what was an electrical insulator at room temperature becomes superconducting!

Now, high temperature is all relative when your reference point is absolute zero. YBCO (yttrium barium copper oxide) has superconducting properties below 92K (or -181.15 °C). This is still a significant breakthrough because liquid nitrogen can be used as the coolant (in place of liquid helium).

Commercial material with superconducting properties above about 140K (where Freon, a common refrigerant, can be used) or warmer…now that’s a disruptive superpower.

In addition to increasing the generation capacity of wind turbines by almost an order of magnitude, superconductors have potential to ‘supe-up’ a wide range of other applications. Emerging and future applications for high temperature superconductors include smart grid and electrical power transmission, transportation, power storage devices, and medical applications.

Associate, Pangaea Ventures Ltd. Sarah is an environmental scientist and MBA who has been active in sustainability efforts for York and Dalhousie universities, as well as the City of Toronto's Environment Office.View Sarah Applebaum's profile on LinkedIn

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Guest Monday, 15 September 2014