Nav: Home

Trembling aspen leaves could save future Mars rovers

March 18, 2019

Researchers at the University of Warwick have been inspired by the unique movement of trembling aspen leaves, to devise an energy harvesting mechanism that could power weather sensors in hostile environments and could even be a back-up energy supply that could save and extend the life of future Mars rovers.

University of Warwick third year engineering undergraduates have in recent years been set the task of the examining the puzzle of why Aspen leaves quiver in the presence of a slightest breeze. University of Warwick Engineering researchers Sam Tucker Harvey, Dr Igor A. Khovanov, and Dr Petr Denissenko were inspired to look more closely at this task they were annually setting for their students and to take the phenomenon one step further.

They decided to investigate whether the underlying mechanisms that produce the low wind speed quiver in Aspen leaves could efficiently and effectively generate electrical power, simply by exploiting the wind generated mechanical movement of a device modelled on the leaf. They have today 18th March 2019 published the answer to that question as a paper entitled "A Galloping Energy Harvester with Flow Attachment" in Applied Physics Letters and the answer is a resounding yes.

University of Warwick PhD engineering researcher Sam Tucker Harvey, the lead author on the paper, said:

"What's most appealing about this mechanism is that it provides a mechanical means of generating power without the use of bearings, which can cease to work in environments with extreme cold, heat, dust or sand. While the amount of potential power that could be generated is small, it would be more than enough to power autonomous electrical devices, such as those in wireless sensor networks. These networks could be utilised for applications such as providing automated weather sensing in remote and extreme environments."

Dr Petr Denissenko further noted that one future application could be as a backup power supply for future Mars landers and rovers.

"The performance of the Mars rover Opportunity far exceeded its designers' wildest dreams but even its hard working solar panels were probably eventually overcome by a planetary-scale dust storm. If we could equip future rovers with a backup mechanical energy harvester based on this technology, it may further the lives of the next generation of Mars rovers and landers."

The key to Aspen leaves' low wind but large amplitude quiver isn't just the shape the leaf but more importantly relates to the effectively flat shape of the stem.

The University of Warwick researchers used mathematical modelling to come up with a mechanical equivalent of the leaf. They then used a low speed wind tunnel to test a device with a cantilever beam like the flat stem of the Aspen leaf, and a curved blade tip with a circular arc cross section acting like the main leaf.

The blade was then oriented perpendicular to the flow direction, which allows the harvester to produce self-sustained oscillations at uncharacteristically low wind speeds like the aspen leaf. The tests showed that the air flow becomes attached to the rear face of the blade when the blade's velocity becomes high enough, hence acting more similarly to an aerofoil rather than to the bluff bodies which have typically been studied in the context of wind energy harvesting.

In nature, the propensity of a leaf to quiver is also enhanced by the thin stem's tendency to twist in the wind in two different directions. However, the researchers modelling and testing found that they did not need to replicate the additional complexity of a further degree of movement in their mechanical model. Simply replicating the basic properties of the flat stem in as a cantilever beam and curved blade tip with a circular arc cross section acting like the main leaf was enough to create sufficient mechanical movement to harvest power.

The researchers will next examine which mechanical movement based power generating technologies would best be able to exploit this device and how they device could best be deployed in arrays.
-end-
NOTES TO EDITORS

The article can be accessed at: https://aip.scitation.org/doi/10.1063/1.5083103

Published by AIP Publishing

(https://publishing.aip.org/authors/rights-and-permissions

Images available at: https://warwick.ac.uk/services/communications/medialibrary/images/march2019/harvesters_img_20190304_100912_003.jpg
https://warwick.ac.uk/services/communications/medialibrary/images/march2019/samtuckerharvey.jpg
https://warwick.ac.uk/services/communications/medialibrary/images/march2019/pd2_2018_m09_small.jpg

For further information please contact:

Alice Scott
Media Relations Manager - Science
University of Warwick
Tel: +44 (0) 2476 574 255 or +44 (0) 7920 531 221
E-mail: alice.j.scott@warwick.ac.uk

University of Warwick

Related Blade Articles:

BAT study shows new vaping technology significantly reduces exposure to toxicants
A vapor product that contains new-to-world technology has significantly fewer and lower levels of certain toxicants compared to cigarette smoke, a study has shown.
For 'blade runners' taller doesn't necessarily mean faster
The governing body for the Paralympics recently lowered the allowable height for sprinters who use prosthetic legs, or blades, during competition.
Organic photovoltaic cell with 17% efficiency and superior processability for large-area coating
The research group from the Institute of Chemistry, Chinese Academy of Sciences, led by Prof.
Wind turbine design and placement can mitigate negative effect on birds
Wind energy is increasingly seen as a sustainable alternative to fossil fuels, as it contributes to a reduction in greenhouse gas emissions.
A cool alternative to air conditioning
An inexpensive passive cooling technology could be used to cool buildings in cities, reducing energy consumption.
Making solar cells is like buttering bread
Formamidinium lead iodide is a very good material for photovoltaic cells, but getting the correct and stable crystal structure is a challenge.
Trembling aspen leaves could save future Mars rovers
Researchers at the University of Warwick have been inspired by the unique movement of trembling aspen leaves, to devise an energy harvesting mechanism that could power weather sensors in hostile environments and could even be a back-up energy supply that could save and extend the life of future Mars rovers.
How to make the push-up work for you
If you want to improve your golf swing, softball pitch, or tennis serve, the push-up is for you.
Distinctive projectile point technology sheds light on peopling of the Americas
In the lowest layer of the Area 15 archaeological grounds at the Gault Site in Central Texas, researchers have unearthed a projectile point technology never previously seen in North America, which they date to be at least 16,000 years old, or a time before Clovis.
Perovskite technology is scalable, but questions remain about the best methods
As perovskite solar cells set efficiency records and the nascent technology becomes more stable, another major challenge remains: the issue of scalability, according to researchers at the Department of Energy's National Renewable Energy Laboratory (NREL).
More Blade News and Blade Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.