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 A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Quantum thermometer or optical refrigerator?
23.06.2017 | National Institute of Standards and Technology (NIST)

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>