permaculture

["Laurence Gaffney" <lgaffney@bigpond.com>]

1.    Toby Hemenway wrote:-
>     "The 1/170,000 yield for solar electricity is quite revealing."

Yes, and it must be remembered that this Transformity (170,000) was a mean 
number from a number of different ways of generating electrical power. The 
Transformity of Electricity generated by modern photovoltaic cells is much 
higher than this. Odum quotes a Transformity of 416,000 for a Solar Voltaic 
Grid (Austin Texas) in his 1996 book titled Environmental Accounting - Wiley  
It would appear that one step devices that take in low grade energy (solar) 
at one end and spit out high grade energy (electricity) at the other have 
inherently higher transformities than a multi-stepped approach such as solar 
to wood to electricity. In the same book Odum quotes a Wood Power Plant 
(Thailand) as having a Transformity of 67,000.

2. Nathan Czuba  wrote:- 
>     "(although there should be a caveat on this related to natural sunlight 
> and just warmth and whatever else, but that's never been figured into any 
> energy budget data I've ever seen [although I imagine that some 
> environmental/ecological economist has had to examine this, anyone have any 
> thoughts?])."

 This I believe is just what Odum does attempt to do though the analysis gets 
abit technical for me. Suggest you check out Table C3 on Page 309 of 
Environmental Accounting. This Table lists Solar Transformities of Global 
Flows.

3.    Toby also wrote:-
>    Thus the US uses 735%, or 7-fold, more usable energy each year than 
> falls on the entire country as solar energy.

Shouldn't the 735 be multiplied by 100 to get the percentage?

I have had another look at Odum's Environmental Accounting Book and I 
understand him to be saying that:-
(A)     Incident annual Sunlight over the USA is 44.8 Z Joules  (4.48E22 J)   
      (page 187)
(B)    Annual USA Emergy Use about 7851 Z solar emjoules   (785.1E22 seJ)    
(page 199)

 It gets complicated as Emergy inputs also include contributions from the 
Earths Deep Heat and Tidal Energy. 

 In any case I totally agree with Toby,s  comment that:-
>    "Bingo. That should suggest the nature of our problem. Energy conversion 
> is the killer.

The Laws of Thermodynamics present a much bigger threat to the American (USA) 
way of life than does Al Queda.

Laurence Gaffney   



Date: Mon, 03 Sep 2007 11:53:11 -0700
From: Toby Hemenway <toby@patternliteracy.com>
Subject: Re: [permaculture] Joules Ain't Joules ( energy/ethanol)
To: permaculture <permaculture@lists.ibiblio.org>
Message-ID: <46DC5817.8070008@patternliteracy.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Laurence Gaffney wrote:
>
>     "amount of total solar energy hitting the Earth is meaningless"
>
> I am not exactly sure what you mean here Toby but I don't think it is 
> meaningless.
Sorry; careless writing. I meant that if all life on the planet can 
capture only 0.05% of solar input hitting the Earth, we shouldn't get 
too excited about how big that total input number is (see below for 
why). It would be a mistake to say, "wow, there's so much energy out 
there--we'll never run out!"

And you're right, Laurance. Odum's energy quality idea is very useful 
here. The 1/170,000 yield for solar electricity is quite revealing.
> Question:- How does the current Solar Emergy consumption of humans in the 
> USA per annum compare with the annual input of Solar Energy over its Land 
> Mass/Boundaries?.
Thanks, Nathan, for doing the quick calculation. To follow Laurance's 
"Joules ain't joules" argument, you then need to multiply by some 
enormous factor to account for quality of energy. In other words, if all 
the energy used by the US were derived via solar conversion to 
electricity, the 0.4333% (US energy use/solar input) would be multiplied 
by 170,000, the conversion inefficiency factor for solar electric. That 
comes out to 735%.

Thus the US uses 735%, or 7-fold, more usable energy each year than 
falls on the entire country as solar energy. Bingo. That should suggest 
the nature of our problem. Energy conversion is the killer.
> PS:-     What is the source of your figures Nathan? 
The numbers Nathan used seemed to have been taken from Wikipedia, as 
they have that exact list at http://en.wikipedia.org/wiki/Solar_powe

Toby
Date: Mon, 3 Sep 2007 00:50:07 -0700 (PDT)
From: Nathan Czuba <nathanaczuba@yahoo.com>
Subject: Re: [permaculture] Joules Ain't Joules ( energy/ethanol)
To: permaculture <permaculture@lists.ibiblio.org>
Message-ID: <727773.70337.qm@web35708.mail.mud.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

The data came from OECD and the US Department of Energy; I can find the exact 
links if you like.  I probably should have added the caveat that the human 
energy consumption data just examines conventional notions of energy (oil, 
coal, nuclear, and I think maybe even biofuels), but not food production or 
things like that.  That being said, it doesn't matter much; at most, it 
increases consumption by a factor of 2-3 (although there should be a caveat 
on this related to natural sunlight and just warmth and whatever else, but 
that's never been figured into any energy budget data I've ever seen 
[although I imagine that some environmental/ecological economist has had to 
examine this, anyone have any thoughts?]).

I don't know the exact answer to your question, but just a quick back of the 
envelope calculation suggests that it is roughly 0.5%.  (total land mass of 
USA, including a bit for ocean under its control)/(total surface area of 
Earth) * 3850 ZJ =~75 ZJ.  (total energy use of earth=0.471 ZJ)*(fudge 
factor=3)*(USA's consumption of total energy=0.23)=0.325 ZJ.  (0.325 ZJ)/(75 
ZJ)=0.4333%

Nathan


Date: Mon, 3 Sep 2007 11:17:26 +1000
From: "Laurence Gaffney" <lgaffney@bigpond.com>
Subject: [permaculture] Joules Ain't Joules ( energy/ethanol)
To: <permaculture@lists.ibiblio.org>
Message-ID: <000801c7edc8$312d6850$0100000a@default1zw8fr1>
Content-Type: text/plain; charset="iso-8859-1"

1.    Toby Hemenway wrote:-
"Doesn't that suggest that referring to total solar energy hitting the Earth 
is meaningless?"
 
I am not exactly sure what you mean here Toby but I don't think it is 
meaningless.
Doesn't the figure for total solar energy hitting the earth (per annum say) 
help provide the basis of an annual budget for sustainable energy use for 
humans and all other life as well as all earth processes?.

2.    Toby also wrote:-
"What matters is not how much energy reaches the planet, but how much can be 
usefully converted."

 Both matter,  and I think the Howard Odum approach which uses a concept of 
energy quality contributes to this discussion. Odum uses a term Solar 
Transformity which he describes as the solar energy calories(joules) required 
directly and indirectly to make one calorie(Joule) of a product, service or 
energy of another kind.
Some examples from page 69 of his 2001 book called "A Prosperous Way Down" 
are :-
(A)    It takes 1500 Calories of Sunlight energy to make 1 Calorie of wind 
energy.
(B)    It takes 50,000 Calories of sunlight energy to make 1 Calorie of 
fossil fuel energy 
(C)    It takes 170,000 Calories of sunlight energy to make1 Calorie of 
electric power.

Note that these are very generalized numbers and that it is the orders of 
magnitude that are significant here.
Note that wind energy is not additional to the earths annual solar energy 
budget as it is derivative.   
So one Joule of Electric Power is of much higher quality than one Joule of 
Sunlight Energy due to its "embedded" solar energy which Odum refers to as 
its Solar Emergy.

Question:- How does the current Solar Emergy consumption of humans in the USA 
per annum compare with the annual input of Solar Energy over its Land 
Mass/Boundaries?.  

Joules ain't Joules

Laurence Gaffney 

PS:-     What is the source of your figures Nathan? 

Date: Fri, 31 Aug 2007 08:45:19 -0700
From: Toby Hemenway <toby@patternliteracy.com>
Subject: Re: [permaculture] energy/ethanol
To: permaculture <permaculture@lists.ibiblio.org>
Message-ID: <46D8378F.8000700@patternliteracy.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Nathan Czuba wrote:
> The total solar energy available to the earth is approximately 3850 ZJ 
> (zettajoules) per year. 
> Oceans absorb approximately 285 ZJ of solar energy per year.
> Winds can theoretically supply 6 ZJ of energy per year. 
> Biomass captures approximately 1.8 ZJ of solar energy per year.
> Worldwide energy consumption was 0.471 ZJ in 2004.
>   
It's those last two numbers that are the most revealing. All the life on 
Earth, after about 3 billion years of evolution, blanketing nearly the 
whole land surface and much of the ocean, can capture 0.05% of the 
sunlight that hits the planet. So how much do you think humans can 
capture? Doesn't that suggest that referring to total solar energy 
hitting the Earth is meaningless? What matters is not how much energy 
reaches the planet, but how much can be usefully converted. All of life, 
all over the planet, can only capture about 4 times more solar energy 
than the energy humans use in the form of petroleum. That gives you an 
idea of how much hardware we'd need to keep up the current rate without 
oil. We already redirect for our needs about 40% of current biomass 
produced on the planet, according to some figures. So it's going to be 
tough to increase that amount without even more seriously disrupting 
ecosystem function.

I'm curious about the figure for wind. Is that how much energy all the 
winds on the whole planet produce? If so, it's meaningless. Remember, 
you have to build the hardware, and keep it running, to catch energy, 
which drops the EROI. That's why plants are only about 7% efficient. PV 
panels themselves are more efficient, but once you add in embedded 
energy costs, transmission and conversion costs, etc., PV drops to worse 
than plants. PV panels take years just to pay back their embedded 
energy, while plants pay as they go.

Here's a thought problem: if a PV panel takes years to pay off its cost 
of construction, how many PV panels will it take to build one PV panel? 
I think if we used most of the petroleum left to build PV panels and 
wind generators, we could keep up our current lifestyle for a while 
after oil gets scarce. But we're not doing that.

Toby