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 Heating quantum matter: A novel view on topology
22.08.2017 | Université libre de Bruxelles

nachricht Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Cholesterol-lowering drugs may fight infectious disease

22.08.2017 | Health and Medicine

Meter-sized single-crystal graphene growth becomes possible

22.08.2017 | Materials Sciences

Repairing damaged hearts with self-healing heart cells

22.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>