How To Use Computers Heat To Generate Electricity

Electronic devices such as computers generate heat that mostly goes to waste. Physicists at Bielefeld University (Germany) have found a way to use this energy: They apply the heat to generate magnetic signals known as ‘spin currents’. In future, these signals could replace some of the electrical current in electronic components. In a new study, the physicists tested which materials can generate this spin current most effectively from heat. The research was carried out in cooperation with colleagues from the University of Greifswald, Gießen University, and the Leibniz Institute for Solid State and Materials Research in Dresden.

The Bielefeld physicists are working on the basic principles for making data processing more effective and energy-efficient in the young field of ‘spin caloritronics’. They are members of the ‘Thin Films & Physics of Nanostructures’ research group headed by Professor Dr. Günter Reiss. Their new study determines the strength of the spin current for various combinations of thin films.

A spin current is produced by differences in temperature between two ends of an electronic component. These components are extremely small and only one millionth of a millimetre thick. Because they are composed of magnetic materials such as iron, cobalt, or nickel, they are called magnetic nanostructures.

The physicists take two such nanofilms and place a layer of metal oxide between them that is only a few atoms thick. They heat up one of the external films – for example, with a hot nanowire or a focused laser. Electrons with a specific spin orientation then pass through the metal oxide. This produces the spin current. A spin can be conceived as electrons spinning on their own axes – either clockwise or anti-clockwise.

Their findings have been  published  in the research journal ‘Nature Communications’.


Tiny Flexible Power Units

Scientists have created a powerful micro-supercapacitor, just nanometres thick, that could help electronics companies develop mobile phones and cameras that are smaller, lighter and thinner than ever before. The tiny power supply measures less than half a centimetre across and is made from a flexible material, opening up the possibility for wearable electronics.
A bottleneck in making portable electronic devices like mobile phones even smaller is reducing the size and increasing the flexibility of the power supplies in electronic circuits. Supercapacitors are attractive power supplies because they can store almost as much energy as a battery, with the advantage of high-speed energy discharge. Supercapacitor electrodes are normally made from carbon or conducting polymers, but these can be relatively costly. A team led by Professor Oliver G Schmidt at the Leibniz Institute for Solid State and Materials Research in Dresden (IFW-Dresden) – Germany – examined the use of manganese dioxide as an alternative electrode material, which is more environmentally friendly and less expensive than the standard materials.

bendable mobile phone

Supercapacitors, as a new class of energy device, can store high energy and provide high power, bridging the gap between rechargeable batteries and conventional capacitors. So we thought a micro-supercapacitor would be an important development in the rapid advance of portable consumer electronics, which need small lightweight, flexible micro-scale power sources” said Dr Chenglin Yan, leader of the research group at IFW-Dresden. “The device could be applied to many miniaturised technologies, including implantable medical devices and active radio frequency identification (RFID) tags for self-powered miniaturised devices.” Dr Yan concluded: “The major challenge we had to overcome in developing this technology was to obtain really high energy density on the micro-scale, at a low cost. The inclusion of gold in our micro-supercapacitor makes it more expensive, so we are now looking at replacing gold with cheaper metals, such as manganese, to make the device more practical for the market.
The research is published in the Royal Society of Chemistry journal Energy & Environmental Science.

Source: AND