A couple of hundred millivolts at microamp levels or less from a tree seems very reasonable. Low potential energy and charge storage is present in anything with unbalanced ion concentrations. Maybe ionic charge could be a force that helps with sap flow up the world's tallest trees? Only one of a kind custom semiconductors can run off that minute of an energy source and they spend most of their time trickle charging the input capacitor and then coming out of sleep/standby mode only briefly before shutting down again for a proportionately long time. It is unlikely that any real commercial application could be derived from this for at least several years.
PJ On Thu, Sep 10, 2009 at 3:34 PM, DON BERTOLETTE <[email protected]>wrote: > Steve- > In rereading the initial post below, > *"A study last year from the Massachusetts Institute of Technology found > that plants generate a voltage of up to 200 millivolts when one electrode is > placed in a plant and the other in the surrounding soil."* > it seems that indeed, the electricity is of little magnitude, effective > perhaps only in nano-technology and even more speculatively, as a measure of > tree health. It's this last item that held my interest! > -Don > ------------------------------ > Subject: [ENTS] Re: tree power!!! > Date: Thu, 10 Sep 2009 05:52:44 -0500 > From: [email protected] > To: [email protected]; [email protected] > > Pardon my skepticism here about this...trees can be conductors of > electricity (dangers of power line contact; also lightning strike patterns) > but I'm a little skeptical regarding the sustainable transmission of > electricity of any magnitude. > > Steve Springer > > ------------------------------ > *From:* [email protected] on behalf of DON BERTOLETTE > *Sent:* Wed 9/9/2009 10:49 PM > *To:* [email protected] > *Subject:* [ENTS] Re: tree power!!! > > PJ- > I'll bet there are differences between species... > -Don > > ------------------------------ > Date: Wed, 9 Sep 2009 17:02:32 -0500 > Subject: [ENTS] tree power!!! > From: [email protected] > To: [email protected] > > ENTS, > > Here is a "must read" on trees from the U of Washington: > http://uwnews.org/article.asp?articleID=51869 > > PJ > > *University of Washington* Electrical engineers Babak Parviz and Brian > Otis and undergraduate student Carlton Himes (right to left) demonstrate a > circuit that runs entirely off tree power.Sept. 8, 2009 | > Science<http://uwnews.org/categories.asp?view=byCategory#Science>| > Technology <http://uwnews.org/categories.asp?view=byCategory#Technology> > *Electrical circuit runs entirely off power in trees* > *Hannah > Hickey<http://uwnews.org/apps/uwnews/public/rss.aspx?q=uwnByAuthorID&numToShow=10000&AuthorID=1801> > * > <http://uwnews.org/apps/uwnews/public/rss.aspx?q=uwnByAuthorID&AuthorID=1801&numToShow=10000> > [email protected] > <http://uwnews.org/photos.asp?articleID=51869&spid=51872> > *University of Washington * The custom circuit is able to store up > enough voltage from trees to run a low-power sensor. > > > You've heard about flower power. What about *tree* power? It turns out > that it's there, in small but measurable quantities. There's enough power in > trees for University of Washington researchers to run an electronic circuit, > according to results to be published in an upcoming issue of the Institute > of Electrical and Electronics Engineers' Transactions on > Nanotechnology<http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=7729>. > "As far as we know this is the first peer-reviewed paper of someone powering > something entirely by sticking electrodes into a tree," said co-author Babak > Parviz, a UW associate professor of electrical engineering. > A study last year from the Massachusetts Institute of Technology found that > plants generate a voltage of up to 200 millivolts when one electrode is > placed in a plant and the other in the surrounding soil. Those > researchers are working with a company, Voltree <http://voltreepower.com/>, to > develop forest sensors that exploit this new power source. > The UW team sought to further academic research in the field of tree power > by building circuits to run off that energy. They successfully ran a custom > circuit solely off tree power. > Co-author Carlton Himes, a UW undergraduate student, spent last summer > exploring likely sites. Hooking nails to trees and connecting a voltmeter, > he found that bigleaf maples, common on the UW campus, generate a steady > voltage of up to a few hundred millivolts. > The UW team next built a device that could run on the available power. > Co-author Brian Otis, a UW assistant professor of electrical engineering, > led the development of a boost converter, a device that takes a low incoming > voltage and stores it to produce a greater output. His team's custom boost > converter works for input voltages of as little as 20 millivolts (a > millivolt is one-thousandth of a volt), an input voltage lower than any > existing such device. It produces an output voltage of 1.1 volts, enough to > run low-power sensors. > The UW circuit is built from parts measuring 130 nanometers and it consumes > on average just 10 nanowatts of power during operation (a nanowatt is one > billionth of a watt). > "Normal electronics are not going to run on the types of voltages and > currents that we get out of a tree. But the nanoscale is not just in size, > but also in the energy and power consumption," Parviz said. > "As new generations of technology come online," he added, "I think it's > warranted to look back at what's doable or what's not doable in terms of a > power source." > Despite using special low-power devices, the boost converter and other > electronics would spend most of their time in sleep mode in order to > conserve energy, creating a complication. > "If everything goes to sleep, the system will never wake up," Otis said. > To solve this problem Otis' team built a clock that runs continuously on 1 > nanowatt, about a thousandth the power required to run a wristwatch, and > when turned on operates at 350 millivolts, about a quarter the voltage in an > AA battery. The low-power clock produces an electrical pulse once every few > seconds, allowing a periodic wakeup of the system. > The tree-power phenomenon is different from the popular potato or lemon > experiment, in which two different metals react with the food to create an > electric potential difference that causes a current to flow. > "We specifically didn't want to confuse this effect with the potato effect, > so we used the same metal for both electrodes," Parviz said. > Tree power is unlikely to replace solar power for most applications, Parviz > admits. But the system could provide a low-cost option for powering tree > sensors that might be used to detect environmental conditions or forest > fires. The electronic output could also be used to gauge a tree's health. > "It's not exactly established where these voltages come from. But there > seems to be some signaling in trees, similar to what happens in the human > body but with slower speed," Parviz said. "I'm interested in applying our > results as a way of investigating what the tree is doing. When you go to the > doctor, the first thing that they measure is your pulse. We don't really > have something similar for trees." > Other co-authors are Eric Carlson and Ryan Ricchiuti of the UW. The > research was funded in part by the National Science Foundation. > ### > > For more information, contact Parviz at 206-616-4038 or > [email protected] or Otis at 206-616-5998 or [email protected]. > > > > > ------------------------------ > Get back to school stuff for them and cashback for you. Try Bing > now.<http://www.bing.com/cashback?form=MSHYCB&publ=WLHMTAG&crea=TEXT_MSHYCB_BackToSchool_Cashback_BTSCashback_1x1> > > > > > > ------------------------------ > Windows Live: Make it easier for your friends to see what you’re up to on > Facebook. Find out > more.<http://windowslive.com/Campaign/SocialNetworking?ocid=PID23285::T:WLMTAGL:ON:WL:en-US:SI_SB_facebook:082009> > > > --~--~---------~--~----~------------~-------~--~----~ Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected] -~----------~----~----~----~------~----~------~--~---
