🚀 go-pugleaf

In <30E1AB5E.514E@bluesky.com> Barry Smith <barry@bluesky.com> writes: 
>
>John DeFiore wrote:
>
>> Perhaps, but Mr. Waltz is correct when he points out that it takes
more
>> energy to make a solar cell, using current technology, than it can
>> return in it's [sic] entire life.
>
>This is bullshit.  (And often repeated bullshit, so let's hose it
off.)
>
>Consider: 1 square meter of 20% efficient cells can typically produce,
>in ten years, 3500 kWh of electricity.  Let's see your argument that
>it takes 3.5 *megawatt-hours* to sputter a 5 micron layer of amorphous
>silicon, or to lay down a 50 micron layer of polycrystalline silicon.
>
>(As I understand it, typical *crystalline* cells have a net energy
>payback time of 1-2 years; newer technology is much less.)
>
Well, maybe-  But let's count the energy used to mine and refine the
materials needed, the transportation cost to the fab, auxiliary cost of
the fab itself (obviously "amortized" over the life of the fab)  energy
to run the fab and get the workers there, packaging costs,
transportation cost to the end user, all the energy costs associated
with hooking up the system and fabricating an inverter (manufacturing
of the parts involved) or power management system, and the energy cost
of running and maintaining the array.  I have seen a calculation that
shows these costs being more than the total output of the cell over
it's life.  Granted, amorphous cells will do better, and the realism of
that calculation is open to question, but if you are considering the
total energy input into the final system, it is not easily dismissable
as bullshit to question the payback.

>> Also, the cells do not last forever.  They are degraded by the
>> UV exposure, weather, oxygen, etc.
>
>Of course; nothing lasts forever.  However, commercial cells have
>typical service life guarantees of ten and twenty years, with no
reason
>to expect prompt failure at the end of that time.
>
Service life maybe- but under what conditions?  What is the degradation
over time?  Is the output power the same as when new?

>> The cost to fabricate and maintain a 1000 square kilometer expanse
>> of solar cells would be prohibitive, let alone 100,000.
>
>This is mere unquantified opinion; what cost is "prohibitive"?
>(Typical prices for electricity from current crystalline cells are
>$0.25 to 0.50; while this is [obviously] not economically competitive
>at current prices, there is both good reason and historical evidence
>to believe that PV prices are far from their long-run real minimum.) 

It's not just the price/KWH, but the construction cost, maintainance
cost, land cost, etc.
I'm not suggesting it will never be competative, just that nobody is
running a conspiracy to keep fossil fuel while the real answer to all
our needs right now is solar.  
>
>> Granted that improvements in
>> technology may eventually let the solar cell produce a net energy
gain
>> in it's [sic] lifetime, but still, let's be practical.
>
>Granted that solar cells *now* produce net energy gain, and that
obvious
>and significant improvements in technology, production, and packaging
are
>likely, perhaps you will reconsider your position.
>
I hope so, in the future.  My argument is that right now it isn't
practical.
>

>Barry Smith, Blue Sky Research
>barry@bluesky.com