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The Future-Population, Resources & The Environment
nipper
post Posted: Jan 23 2020, 09:58 AM
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"The beauty of demographics is that the future has already been written"

https://www.firstlinks.com.au/article/demog...8d8606-83781601



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"Every long-term security is nothing more than a claim on some expected future stream of cash that will be delivered into the hands of investors over time. For a given stream of expected future cash payments, the higher the price investors pay today for that stream of cash, the lower the long-term return they will achieve on their investment over time." - Dr John Hussman

"If I had even the slightest grasp upon my own faculties, I would not make essays, I would make decisions." ― Michel de Montaigne
 
Sav
post Posted: May 8 2007, 08:02 PM
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In reply to: jaolsa on Saturday 05/05/07 12:17pm

hey all... so i finally got the time to read through the posts here.

Some great as per usual from the ss crew. Jaolsa - i had no idea about Stan Meyer - so I looked around and came across alot of info on water fuel cells. Disappointingly....alot of it criticising the water fuel cell saying that its not possible to get enough energy to drive a car on! If stan pulled this off which I believe, then its obvious the goverments holding things back to keep up their revenues from tax on oil.

I dont see it as an extreme task to set up hydrogen refuelling stations across the nation and just imply a tax on this. Surely you would think cashed up companies like shell etc would want to lead the way and create refill stations around australia ( I understand theyre doing it in the UK). Water wont run out in a hurry - unlike oil. I dont know, im not clued into the overall techincality side of it to make comments like that but it seems like an option that needs to be undertaken now.

So as i progressed through the rest of the posts I had to laugh .....Krumbs.... absolutely classic comment!

QUOTE
How the heck did we get into this?


Pretty technical stuff here on solar panels...... wayyy above my head at present so I might let that one go!

Ill be attending a function based on the BedZED development in the UK in the next few weeks.... so will hopefully pick up a few tips re sustainable 0 carbon emission design - and possibly get to utilise some of their techniques in developments here.

http://www.bioregional.com/programme_proje.../bedzed_hpg.htm

http://www.peabody.org.uk/pages/GetPage.aspx?id=179

Although not very aesthetically appealing the resultant environmental outcomes are significant and it could be a possibility of how we live in the future unless we can stop the carbon output. Ive mentioned this numerous times before, but the global warming we're experiencing now is a result of pollution from the 60's due to the earths inertia. Come 2040 it raises major concerns as to what warming will be experienced from the population being over twice the size it was in the 60's!

 
Sav
post Posted: May 7 2007, 06:08 PM
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In reply to: bello on Monday 07/05/07 03:27pm

nice find Bello. Wonder if I can get carbon credits from not having babies? tongue.gif

 
bello
post Posted: May 7 2007, 03:27 PM
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Haven't had enough time yet to read the thread but maybe this is relevent to population theme :

http://www.theaustralian.news.com.au/story...1-30417,00.html

 
Krumbs
post Posted: May 7 2007, 12:18 PM
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In reply to: kahuna1 on Sunday 06/05/07 12:01pm

[QUOTE]Any contention about the energy in .... and energy out and reference to thermodynamics's with regards to Photovoltaic panels ... I think is wrong. Sorry .... A photovoltaic cell converts light energy from the sun and splits off the photon creating electricity due to the crystalline nature of the panels and as such there is no chemical reaction which is what the law of thermodynamics is all about[QUOTE]

K, the beginning and the end of this debate lies in the first law of thermodynamics:

"In any process, the total energy of the universe remains constant."

Electromagenetic energy, of which "light" is a sub-set, consists of elementary particles called photons, which have neither mass not charge. In photovoltaics it's generally accepted (I think) that we get about one electron per photon, resulting in a theoretical efficiency of 31%, the rest being lost, or wasted, as heat.

Practically this is reduced to 25%, the reason being a single material has only a limited band capture ability above and below which it just gets hot. Multiple band stacks with different materials to capture energy from different spectra increases the efficiency and a lot of research is being directed at this - theoretical limits like 72% have been reported. Of course this complexity adds to cost, but that's progress.

The silicon has to be "tricked" into releasing an accepting electrons, a process called doping - adding P creates a negative bias or surplus electron in the crystal structure, and adding B creates a positive bias, or hole into which these surplus electrons can fit when mobilized by photon excitation. Thus an electrical current is born when this process takes place across a junction or diode. It is the opposite of a LED, which releases photons (light) when a current is applied.

How the heck did we get into this?


 
balance
post Posted: May 6 2007, 11:34 PM
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In reply to: kahuna1 on Sunday 06/05/07 12:01pm

Hi K,
In short, I believe a photon of sufficient energy will liberate an electron from its orbit around the nucleus.Electrons flow from one atom's orbit to the next.The "holes" left by the travelling electron(s) travel in the other direction.Hence -ve and +ve polarity .
More physics than chemistry.

The bind is efficiency of the material , the efficiency of the conversion to an A.C. voltage and of course the available light due to factors such as night, bad weather, etc.

Using watts at different voltages can throw you a bit.Prob best to use power consumed versus power produced post conversion to 240v a.c. Given that power in watts is equal to the volts times amps, conversion to 240vac is not a huge problem.

Just knock some 10% or so for losses in conversion. Watts will reduce to say 300 for simplicities sake ,volts is bumped up to 240 and of course current (amps) is sacrificed from roughly 14 to 1.25.

Rather than 40 years call it 8 due to night time, bad angles,dirty panels and weather losses.Say 20% availability over 40 years ?

My brain hurts and the numbers plugged in ( yes its a pun) will vary the end result quite a bit and becomes an academic exercise.But from a back of the envelope calculation I think its a reasonable starting point.

So I think the 100w for 5.8 years is a bit low.Using the above maybe 10 years ?
I'm sure someone will blow these figures with a more scientific approach using real efficiencies and useable hours per day averages (and some real knowledge and calculator) so I stress the back of the envelope example produced.

The thing I really like about solar is the decentralisation of production.Price of course is the problem right now.









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Sav
post Posted: May 6 2007, 07:01 PM
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In reply to: kahuna1 on Sunday 06/05/07 11:01am

Great posts as always kahuna. Been a while since I studied thermodynamics and fluid mechanics... id have to do a refresher course!

these links might help to the solar issue...

http://www.solarserver.de/wissen/photovoltaik-e.html

http://science.howstuffworks.com/solar-cell3.htm

http://www1.eere.energy.gov/solar/pv_basics.html

 
kahuna1
post Posted: May 6 2007, 11:01 AM
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Solar panels ...

I was the one who raised it ....

Not going to pretend to be a scientist but know a bit about solar stuff and the whole energy side.

Any contention about the energy in .... and energy out and reference to thermodynamics's with regards to Photovoltaic panels ... I think is wrong.

Sorry .... A photovoltaic cell converts light energy from the sun and splits off the photon creating electricity due to the crystalline nature of the panels and as such there is no chemical reaction which is what the law of thermodynamics is all about.

As the name suggests Thermo ... heat and energy via this means where a solar panel relates to light and photons ... one is nothing to do with the other ?. The Thermodynamics's branch relates to a chemical reaction where we are talking about endothermic and exothermic reactions where one releases heat and the other requires heat to react.
Basically the law states if you require 100 units of energy to create one reaction ... going back the other way it will not and can not produce more than the 100 units of energy with the reverse reaction.

Solar panels the energy output comes from light from the sun .... an external factor to the production of the electricity the other end. Nothing to do with a chemical reaction releasing heat or storing heat. Not being a pointy head scientist ... there is of course a reaction of freeing an electron off the crystalline structure of the silicon going on but the energy INPUT is coming from the sun and the crystalline structure and free nature of this electron is an inherent part of silicon and as such there is little or no energy required to get it into this state as its a bloody element. Its number 14 on the periodic table.

The reaction is similar to many other elements and Iron just loves to rust and form Iron oxide .... hydrogen doesn't like being alone either .... Silicon when in its natural normal crystalline structure and exposed to light likes to shed its free electrons and convert photons from the light of the sun .....

Maybe someone can correct me ... not a scientist but when a solar panel and the new next generation ones have a rated life of 40 years and 350 w output at 24 volts ... its about the same as having a 100w globe running 24 hours a day for 5.8 years. One does not equate to the other and I think the reaction is neither endothermic or exothermic but something else a conversion of photons into electrons via application of energy in the form of sunlight.

Interesting if someone could explain this in non geeky language ... I could very well be wrong with my own understanding.

Cheers



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All views expressed are my own opinions. While I take every care when posting no guarantee to the absolute veracity of the postings is given or implied. Please do your own reseach and consult a professional investment advisor before investing.
 
kelt
post Posted: May 5 2007, 11:04 PM
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In reply to: denpal on Saturday 05/05/07 06:53am

If you bothered to read my post, I didn't say the spinning top didn't work. I said it didn't emmulate anti-gravity.

I worked fine and she even waved her hand underneath it. As a source of energy goodluck.



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redpencil
post Posted: May 5 2007, 09:03 PM
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In reply to: Krumbs on Saturday 05/05/07 06:18pm

As far as photovoltaic cells go, the energy payback can be as little as 2 years.

For a discussion on this see:

Can Solar Cells Ever Recapture the Energy Invested in their Manufacture?
Richard Corkish
Photovoltaics Special Research Centre
University of New South Wales, Sydney 2052 Australia
from Solar Progress
(Australia and New Zealand Solar Energy Society)
vol. 18, No. 2, pp. 16-17 (1997)]

(Available on Google.)

This study is now 10 years old and since then efficiencies have improved significanly.

Good quality solar panels will now last at least 20 years, maybe even 40+.

As for water powered cars, as Scotty said "You cana change the laws of physics". That's the first, second and third laws of thermodynamics

Cheers

Red

 
 


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