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 Subnano lead particles show peculiar decay behavior
25.04.2018 | Ernst-Moritz-Arndt-Universität Greifswald

nachricht Getting electrons to move in a semiconductor
25.04.2018 | American Institute of Physics

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: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Getting electrons to move in a semiconductor

25.04.2018 | Physics and Astronomy

Reconstructing what makes us tick

25.04.2018 | Physics and Astronomy

Cheap 3-D printer can produce self-folding materials

25.04.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>