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Posted by Mauried on September 1, 2008, 2:45 am
 
On Sun, 31 Aug 2008 12:12:40 +0100, Eeyore


Heard an interesting side issue related to CO2 production and ETS.
Most people seem to want to do something to combar AGW, leaving aside
the issues of whether its real or not, but how many people even care
when they buy some goods at their local shop which was imported from a
country that doesnt have an ETS scheme like China.
If the CO2 emitted to produce a product that you buy was in fact
emitted somewhere else, its no longer a problem.
People only seem concerned about how much CO2 is emitted in their
country, they dont care about emissions elsewhere.

Same goes for exports.
Nothing at all wrong in exporting millions of tonnes of coal, as long
as the coal is turned into CO2 somewhere else.

Id like to know how much CO2 is produced to manufacture a 100W solar
panel.



Posted by Eeyore on September 1, 2008, 3:26 pm
 


Mauried wrote:


These things used to be called environmental impact statements. Yes, I'd very
much
like to see one for a PV panel. Funny how that data doesn't seem to be there.

BTW did you know something like 30% of all oil use is in shipping, a large part
of
which is bringing those cheap Asian goods to us ! Whilst the greens fuss over the
relatively tiny 8% used in aviation.

The have amazingly myopic vision.

Graham



Posted by BobG on September 1, 2008, 6:06 pm
 On Aug 31, 10:45pm, maur...@tpg.com.au (Mauried) wrote:

==========================
=================
Let's guess the panel costs about $50 and there is about 10% profit
in there, leaving about $00 for the 'parts'... silicon wafers and
aluminum frame and glass cover, all of which use lots of electricity.
I bet 75% of that $00 is electricity... $00 or so. Thats 3000KWhr or
so. If the coal plant is 40% efficient, you need 7500KWhr thermal. I
know a KWhr is 3412 BTU and coal is about 15000 BTU per lb, but I dont
know what % of the combustin gas is CO2. Care to weigh in Graham?


Posted by Eeyore on September 1, 2008, 11:23 pm
 

BobG wrote:


You've confused me already by introducing BTUs.

You want to know the volume of CO2 released by burning 7.5MWh (thermal) of
coal ?

But a simpler estimation of environmental impact could be power taken to
manufacture vs power produced.

In this case you've estimated 7.5MWh to make the panel.

A really GOOD insolation for the panel (in the USA) would be around
5kWh/day average (parts of California) and over the quoted lifetime of 25
years, receive some 45 MWh.

At 15% conversion efficiency (about the best you can currently get), that
would produce 6.8MWh of electricity or a net LOSS of 10% over the
manufacturing energy.

Of course if it lasts longer without being hit by a giant hailstone or
killed in any other way and doesn't age too badly (after 25 yrs you can
actually expect output to be 10% down) you MIGHT  eventually get in
'energy profit'.

Graham



Posted by Ron Rosenfeld on September 2, 2008, 1:02 am
 On Tue, 02 Sep 2008 00:23:34 +0100, Eeyore


Take a look at the paper by Erik Alsema and Mariska de Wild-Scholten,
“Reduction of Environmental Impacts in Crystalline Silicon Photovoltaic
Technology– An Analysis of Driving Forces and Opportunities,” presented at
the Materials Research Society Fall 2007 Symposium, Boston, USA, November
2007.

http://www.ipcrystalclear.info/Shared%20Documents/Project%20publications/SP6%20paper%20for%20MRS%20Fall%20Symposium%202007%20 (UU,%20Alsema%20and%20ECN,%20de%20Wild).pdf

http://tinyurl.com/5rpwfm   (hopefully one of these will work)

They calculated Energy Payback Time defined as the total energy (KWH)
required to produce the system divided by the Annual Energy Generation
(KWH/yr).

They looked at rooftop systems in southern Europe, and assumed an
irradiation of 1,700 kWh/m2/yr, and assumed a system efficiency of 75% to
account for losses from module temperature, wiring and inverter
inefficiencies.

They looked at different types of PV manufacturing technology, including
ribbon, multicrystalline, monocrystalline and thin-film.

They included not only the direct energy used to produce the system, but
also the "embodied energy" of the raw materials used in manufacturing all
the parts of the PV system.

They also included the BOS components (racks, inverters, wires, etc).

In 1975, the EPBT was about 20 years.

In 2006, the EPBT was 1.5 - 2 years depending on the type of silicon module
studied.

In looking at the reasons for the drop in EBPT from 1975-2006, they project
the possibility of further reductions in the future, perhaps to less than 1
year.
--ron

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