Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Gone with the wind–why the fast jet stream winds cannot contribute much renewable energy after all

30.11.2011
The assumption that high jet steam wind speeds in the upper atmosphere correspond to high wind power has now been challenged by researchers of the Max Planck Institute for Biogeochemistry in Jena, Germany.

Taking into account that the high wind speeds result from the near absence of friction and not from a strong power source, Axel Kleidon and colleagues found that the maximum extractable energy from jet streams is approximately 200 times less than reported previously. Moreover, climate model simulations show that energy extraction by wind turbines from jet streams alters their flow, and this would profoundly impact the entire climate system of the planet.


Graphics depicting the calculations for high kinetic energy transport (upper panel) versus maximum kinetic energy extraction rates (lower panel) from jet streams. Please note the units.
L. Miller / MPI-BGC Jena


Artificial picture illustrating potential extraction of jet stream wind power.
L. Miller / MPI-BGC Jena

Jet streams are regions of continuous wind speeds greater than 25 m/s that occur at altitudes of 7-16 km. Their high speeds seem to suggest an almost unlimited source of renewable energy that would only need airborne wind energy technology to utilize it. Claims that this potential energy source could “continuously power all civilization” sparked large investments into exploitation of this potential energy resource.

However, just like any other wind and weather system on Earth, jet streams are ultimately caused by the fact that the equatorial regions are heated more strongly by the sun than are polar regions. This difference in heating results in large differences in temperature and air pressure between the equator and the poles, which are the driving forces that set the atmosphere into motion and create wind. It is this differential heating that sets the upper limit on how much wind can be generated and how much of this could potentially be used as a renewable energy resource.

It is well known in meteorology that the high wind speeds of jet streams result from the near absence of friction. In technical terms, this fact is referred to in meteorology as “geostrophic flow”. This flow is governed by an accelerating force caused by pressure differences in the upper atmosphere, and the so-called Coriolis force arising from the Earth’s rotation. Because the geostrophic flow takes place in the upper atmosphere, far removed from the influence of the surface and at low air density, the slow-down by friction plays a very minor role. Hence, it takes only very little power to accelerate and sustain jet streams. “It is this low energy generation rate that ultimately limits the potential use of jet streams as a renewable energy resource”, says Dr. Axel Kleidon, head of the independent Max Planck Research Group ‘Biospheric Theory and Modelling’. Using this approach based on atmospheric energetics, Kleidon’s group used climate model simulations to calculate the maximum rate at which wind energy can be extracted from the global atmosphere. Their estimate of a maximum of 7.5 TW (1 TW = 10^12 W, a measure for power and energy consumption) is 200-times less than previously reported and could potentially account for merely about half of the global human energy demand of 17 TW in 2010.

Max Planck researchers also estimated the climatic consequences that would arise if jet stream wind power would be used as a renewable energy resource. As any wind turbine must add some drag to the flow to extract the energy of the wind and convert it into electricity, the balance of forces of the jet stream must also change as soon as energy is extracted. If 7.5 TW were extracted from jet streams as a renewable energy source, this would alter the natural balance of forces that shape the jet streams to such an extent that the driving atmospheric pressure gradient between the equator and the poles is depleted. “Such a disruption of jet stream flow would slow down the entire climate system. The atmosphere would generate 40 times less wind energy than what we would gain from the wind turbines”, explains Lee Miller, first author of the study. “This results in drastic changes in temperature and weather”.

The Max Planck study was published in the scientific journal Earth System Dynamics on November 29th, 2011. This study illustrates that fast winds are not always strong and powerful. Seemingly environmentally-friendly renewable energy technologies need to be carefully evaluated in the context of how the whole Earth system works.

Contact:
Dr. Axel Kleidon
Max Planck Institute for Biogeochemistry, Jena, Germany
Phone: +49 3641 576217
Fax: +49 3641 577200
Email: akleidon@bgc-jena.mpg.de
Background Information:
The Max Planck Institute for Biogeochemistry, founded in 1997, is dedicated to the study of long-term interactions among the biosphere, atmosphere, geosphere and the oceans. The research aims of the Institute include:
- quantifying the role of these interactions in the control of the Earth’s climate in a time of increasing anthropogenic impact;
- developing a quantitative and predictive understanding of the regulation of processes in ecosystems and their attendant biogeochemical cycles in the face of climate change;

- and investigating feedback mechanisms at the Earth’s surface that involve vegetation, atmospheric composition and climate. For more information see www.bgc-jena.mpg.de.

The independent Max Planck Research Group „Biospheric Theory and Modelling“, headed by Dr. Axel Kleidon, develops and uses theoretical approaches and numerical simulation models to investigate the role of the biota in driving the global geochemical cycles within the Earth system and how these affect the climatic conditions. It applies complex systems theories as well as thermodynamics to describe biotic effects on the environment. The group develops a range of simulation models to reproduce and explain the observed geographic variation of terrestrial vegetation, fluxes of energy, water, carbon, and other elements for the present-day and its past evolution. These approaches are used to evaluate the causes and consequences of human modifications to the Earth system (www.bgc-jena.mpg.de/bgc-theory).

Further information on the contents of this press release is available at www.bgc-jena.mpg.de/bgc-theory. Original data are published in:

- L.M. Miller, F. Gans, & A. Kleidon, 2011: Jet stream wind power as a renewable energy resource: little power, big impacts; Earth Syst. Dynam. 2, 201–212, 2011, doi: 10.5194/esd-2-201-2011.

Dr. Eberhard Fritz | Max-Planck-Institut
Further information:
http://www.bgc-jena.mpg.de/
http://www.bgc-jena.mpg.de/bgc-theory

More articles from Earth Sciences:

nachricht Research sheds new light on forces that threaten sensitive coastlines
24.04.2017 | Indiana University

nachricht NASA sees the end of ex-Tropical Cyclone 02W
21.04.2017 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Molecular libraries for organic light-emitting diodes

24.04.2017 | Life Sciences

Research sheds new light on forces that threaten sensitive coastlines

24.04.2017 | Earth Sciences

Making lightweight construction suitable for series production

24.04.2017 | Machine Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>