Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Electricity that comes from noise

12.05.2015

Computers generate heaps of surplus heat. Components that use this energy sensibly were already foreseen a few years ago. Now, physicists from the University of Würzburg have managed to create such parts in the laboratory.

The smaller and more powerful that computer chips are the more heat they produce. This causes financial problems, because cooling costs money.


A new development by Würzburg physicists can produce a rectified current from differences in temperature. This means, for example, that sensor networks can be supplied with energy.

Graphic: Fabian Hartmann

For this reason, Google is keen to build new server farms in northern latitudes, such as Finland, where the Arctic cold keeps the servers at low temperatures virtually by itself. Excessive heat generation imposes limits on progressive miniaturization, making it difficult to develop even smaller and more powerful processors.

Publication in Physical Review Letters

The fact that this energy could be used in a special way to produce electricity was foreseen theoretically by physicists from the University of Geneva a few years ago. Now, a team of physicists at the University of Würzburg have succeeded in translating this theory into practice.

Scientists at the Department of Applied Physics under Professor Lukas Worschech and Professor Sven Höfling have created a component that is capable of producing a rectified current from differences in temperature. The scientists have presented their work in the journal Physical Review Letters.

“With our component we generate energy from random movements,” says Dr. Fabian Hartmann to explain the underlying principle. In this case, this involves movements of electrons in structures that are only a few billionths of a meter in size. The greater the fluctuations in this structure, the more intense the random movements are – the physicist speaks of “noise”. “Where the heat is great we find a high level of noise. In colder areas the noise is lower,” explains Hartmann. The trick now is to produce a rectified current from this difference.

A two-dimensional electron gas

At the Gottfried-Landwehr-Laboratory for Nanotechnology at the University of Würzburg, the physicists “created” a structure referred to in the technical jargon as a “quantum dot”. This involved building an aluminum gallium arsenide heterostructure in layers on a carrier material that is only a few micrometers in size. Then onto this there they etched special structures in which electrons can move around.

However, the gap that offers the electrons room is only a few nanometers wide. This therefore creates a two-dimensional electron gas in which the directions of movement are heavily restricted. “In doing this we achieve very high electron mobility in a defined area without scattering processes,” is how Hartmann outlines the result. If you then bring two of these quantum dots of different temperatures close together, this produces the desired effect: Random movement, high-level noise on one side, generates directed movement on the other – a direct current.

Better than thermoelectric elements

It was, of course, already possible to generate energy from differences in temperature in the form of electricity. “Thermoelectric elements,” as they are called, are capable of this. The spectrum of possibilities ranges from the wristwatch, which receives its drive energy from the small difference in temperature between ambient air and body heat, to thermoelectric units, which use waste heat from a combustion process, and all the way through to the space probe Cassini, which converts the decay heat of Plutonium-238 into electrical energy.

However, the physicists believe that thermoelectric elements have a serious disadvantage: “With them, heat flow and electrical current are rectified,” explains Fabian Hartmann. This means that while they produce electricity, these materials automatically reduce the difference in temperature until the difference has disappeared. As a result, electricity can no longer flow.

“With our construction elements, on the other hand, these two processes are made independent of one another. The differences in temperature are therefore easier to maintain,” says Hartmann.

Low energy efficiency with potential

The energy efficiency of the components sounds to the layman like it is barely anything. Around 20 picowatts is the power from such an element, says the physicist. 50 billion of them generate as much as one watt. Is the development of these parts, therefore, just a gimmick in the laboratory?

Absolutely not, says Hartmann. For one thing, a common processor already has more than one billion transistors, which all produce heat. For another, it is one of the goals of his work to supply autonomous sensor networks with energy in this manner! And only a few microwatts were needed to achieve this.

Voltage Fluctuation to Current Converter with Coulomb-Coupled Quantum Dots. F. Hartmann, P. Pfeffer, S. Höfling, M. Kamp, and L. Worschech. DOI: 10.1103/PhysRevLett.114.146805

Contact

Dr. Fabian Hartmann, Department of Applied Physics, T: +49 (0)931 31-88579, e-mail: fhartmann@physik.uni-wuerzburg.de

Gunnar Bartsch | idw - Informationsdienst Wissenschaft
Further information:
http://www.uni-wuerzburg.de

More articles from Physics and Astronomy:

nachricht Astronomers find unexpected, dust-obscured star formation in distant galaxy
24.03.2017 | University of Massachusetts at Amherst

nachricht Gravitational wave kicks monster black hole out of galactic core
24.03.2017 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>