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Electricity from trees?

Electricity from trees?

Electricity from trees?

(OP)


Plugged in: Startup hopes to tap electricity from trees

“Lagadonis said tests have generated 0.8 volts to 1.2 volts by driving an aluminum roofing nail half an inch into a tree attached to a copper water pipe driven 7 inches into the ground. But the electricity is useless because it's unstable and fluctuates.”

http://www.bizjournals.com/masshightech/stories/2006/01/09/story12.html?pag
e=2

RE: Electricity from trees?

Um, what's the electrical potential difference between aluminum and copper?

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

RE: Electricity from trees?

(OP)
In Electropotential Series of Metals
Aluminium has 1.3 V
Copper is –0.345 V
The difference is 1.3-(-0.345)=1.645 V

RE: Electricity from trees?

Isn't journalism wonderful?  Damn, what am I doing trying to develop real technology- there's got to be SO much more money in being a charlatan!

RE: Electricity from trees?

Um, I've never seen it with a living tree but isn't that the same as the old trick with a potatoe, or was it a citrus fruit?  

I think I know people who got the little kit to make a potatoe powered clock as a kid, I certainly recall seeing it on TV or in some kids science book.

Anyway seems odd.  In the unlikely event it leads anywhere cool but I'm extremely sceptical.

RE: Electricity from trees?

(OP)



This seems to me like an electrolytic cell where aluminium nail act as anode and copper water pipe, work as cathode the electrolyte would be the plant sap.

luis

RE: Electricity from trees?

Some very low current microprocessor companies have demo kits that operate a microprocessor off two electrodes stuck into a orange or lemon. Yet, I don't see Texas Instruments claiming that a fruit smoothie is the solution to the world's energy problems!

I used to have a long-wire antenna going from the house to a tree. The antenna would easily light several neon bulbs. Maybe I sould claim that I developed it first and get my own venture capital funding!

RE: Electricity from trees?

Long ago Popular Mechanics had plans for a model electric  boat,  The boat had 3 or 5 keels. alternating copper and zinc. The thing was supposed to run forever without batteries. In saltwater of course.

RE: Electricity from trees?

You know how to get more power from that tree?
Cut the damn thing down and throw it into my stove.  Saves my electricity heating bill.  Problem solved.

Frank "Grimey" Grimes
Rule 25. of Swanson's "Unwritten Rules of Management"
Have fun at what you do. It will reflect in your work. No one likes a grump except another grump.

RE: Electricity from trees?

BJC:  not forever, just until the zinc runs out!  Consider it a zinc-fueled boat, just as the tree idiot is fueling his process with aluminum nails.  He's just choosing a lousy electrolyte in the form of a tree, and hence building a very poor battery.

RE: Electricity from trees?

I think Grimes may be making a good point.

Perhaps even better, cut down the tree & burn it for engergy.  Then replace it with a more rapidly growing crop to repeat the cycle.

Obviously this doesn't take into account other environmental issues but...

RE: Electricity from trees?

(OP)


As trees will have lots of led lights, during the night the photosynthesis will keep going on and the release of CO2 will be substantial lowered.

At Christmas times it will not be necessary to buy lots and tots of made in china Christmas lights because trees will be already lightened.

Luis marques

RE: Electricity from trees?

It's terrible that a journalist for 'Mass High Tech: The Journal of New England Technology' doesn't know basic science!

The correct method for drawing energy from trees requires a knowledge of Latin (Acer saccharum), climatology, machining/woodworking & gravitational flow:*
Tapping into source:


Sophisticated collection network:



Thermophysical concentration:


Quality engineers:


Energy content of product is 50 Kcal/tablespoon
(Note: A food Calorie = 1000 scientific calories)

*Fortunately, the Native Americans had developed the process eons ago, so no need to depend upon the idiots mentioned in the OP!

RE: Electricity from trees?

Quote (GrimesFrank):

You know how to get more power from that tree?

Rather than directly heating your home, use the wood to boil water, run a heat engine by steam, run a heat pump by heat engine and use the discharged heat from both heat engine and heat pump into your house. You will have more heat energy now.(Courtesy : Lord Kelvin)

I will never know whether this is a technical calculation or entrepreneurialbugeyed


RE: Electricity from trees?

Quark, more energy?  

Or do you mean more useful energy/able to make use of more of the energy?

RE: Electricity from trees?

Suppose, you get 1kW heat by direct combustion, then it is possible to get about 5kW by above arrangement, theoretically. You will straight away get 1kw from the fuel as usual + you have heat energy extracted by heat pump from atmosphere.

RE: Electricity from trees?

Hmm, I'm wishing I had my thermodynamics notes handy right now as I have a feeling I'm being an idiot but something doesn't sound right to me.

I was never any good at thermodynamics (not too bad at propulsion though strangely) so I may well be wrong.

Perhaps I was harsh in my previous post about engineering journalism and am no better myself.

RE: Electricity from trees?

KENAT:  I think quark's figures are not quite right.  You burn the tree to produce heat to run a heat engine (say 30% efficient tops) but the balance of the heat goes to beneficial use to heat your house (consider it a "co-generation" scheme if you will- the heat engine uses your home as its "cold reservoir". The work you generate from the first heat engine is used to drive another heat engine (the heat pump), which depending on the temperatures of your house and its surroundings could be as much as 400% "efficient" in terms of useful watts of heat into your living space per watt of work into the heat pump.  So at best, your 1 kW of heat energy from the tree is giving you about 0.70 +4*(0.3)= 1.9 kW of useful heat into your home.

RE: Electricity from trees?

Yes, my figures are not quite right, in the sense that I was a bit conservative. The original calculation by Kelvin, considering Carnot efficiencies for heat engine(steam based, at 200C) and heat pump, gives 6kW for every 1kW of direct combustion. The detailed calculation may be out of the scope of this forum.

RE: Electricity from trees?

oddly enough I was looking at coefficients of performance for heat engines. They typically run at around 3-7 (that is heat out/mech work in), which seems like money for old rope.

But a steam engine running at 200 C, even into 20C heat sink, cannot exceed

1-293/473 =38% efficiency

So for every kW of fuel in you might get .38*7 =3 kW  of heat out

Admittedly you might manage better than a CP of 7, as a lot of your reject heat will be available, and at more than 20 deg C, but this cuts into your steam engine efficiency. Interesting tradeoff actually - given a required output heating temperature Tout, and a given upper temperature TH, and a given environmental temperature Tin, what is the optimum cold side temperature TC of the Carnot cycle that is providing the mechanical energy? I suspect it depends on how much plant complexity you are prepared to buy.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

RE: Electricity from trees?

Greg:  if you managed to use the home itself as the cold reservoir for the steam engine, I guess you'd get the 1-.38 kW too.  But a COP of 7 is pretty optimistic- it presumes a better quality heat reservoir for the heat pump to draw from than most of us have at hand.  You would need to drill a lot of expensive wells to provide access to the only decent source at hand to most of us- the earth itself- to obtain such a favourable COP.

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