Environmental Engineering Reference
In-Depth Information
From the resource side, for a thin-
lmcell whose absorber is 3
m
m in thickness, the
volume of active material required is (105.9 km)
2
33 645m
3
408 railroad
coal cars at 82.5m
3
per coal car. As a comparison, a trainload, for example, of coal, is
around 100 cars. The important point is that we are not talking about a trainload per
day, as in shipping of coal, but four trainloads to solve entirely the electricity needs of
the country for the future.
An analysis of CdTe cells is similar, with emphasis on the amount of Te required.
The density of CdTe is 5850 kg/m
3
, with Te comprising 0.53 of the mass, thus
3100 kg/m
3
of Te in CdTe. Again taking the thickness of the absorber layer as 3
m
m,
with volume 33 645m
3
as above, themass of Te needed is 104.3
3
m
m
¼
10
3
metric tons. (On a volume basis, the Te would be about 0.5 of the volume, thus
16 822m
3
.) This exceeds the annual production of Te, but it appears that new sources
of Te are likely to be found.
On another estimate (http://en.wikipedia.org/Wpiki/Cadmium_telluride_photo-
voltaics), First Solar CdTe modules have area 0.74m
2
and deliver 73.75 watts (peak).
The area of these modules for 460 GW is then 6.2
10
6
kg or 104
10
9
m
2
if the sun shines for 24 h,
but 1000/205 times larger on the average solar input of 205W/m
2
, thus 3.04
10
10
m
2
. This is the module area, and the land area must be larger to allow access,
perhaps to 4
10
10
m
2
. This is a plot of land of side 200 km
125mi on a side, and is
twice the size of our original estimate. It may be that the CdTe modules are half as
ef
¼
cient as our assumed 20%.
If we scale from the 25 square miles (see Chapter 6) for the 2GW (peak) solar farm
planned for China, the area for 460 GW at average sun energy 205W/m
2
is (460/
28 050mi
2
, or a plot 167 miles on a side. This is
larger than our original estimate of 66 miles on a side and the GCEP estimate of
180 km
2)
(1000/205)
25 square miles
¼
180 km, which is 113 miles on a side.
If we assume First Solar can sell modules at a pro
t for about $1/Wp, the capital
cost of the cells is
$460 billion. We know that First Solar sold 1.4 GW
of modules in 2010. So the problem is of scaling up this production by a factor 328 for
1 year or by a factor of 66 if the production spans 5 years. This deals only with
electricity and only in the United States. In the United States, the total average power
(all energy sources, coal, hydro, and nuclear) is 3.17 TW, thus 6.9 times the electric
power usage we have been describing (see Figures 1.1 and 1.2). Conceivably, all power
could eventually be derived from solar PV and wind, converted into electricity, and
used for electric heating, electric autos and transport, and so on. In that case, the
numbers given above would be multiplied by 6.9 (see Figure 1.7a).
(1000/205)
10.4.2
Economics of
Printing Press
CIGS or CdTe Cell Production to Satisfy U.S.
Electric Demand
A
rst generation printing press for roll-to-roll processing CIGS CuIn
1
x
Ga
x
Se
2
cells is in operation at the Nanosolar plant in California, which received $150 million
in private funding. According to the
New York Times
[129], the company shipped its
first solar panels, containing cells printed onto aluminum foil [132]
selling for less than
