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re: pv panels- energy cost to produce
16 aug 2000
joel davidson wrote:
>> >"photovoltaic cells can produce as much as a 4:1 return on the energy
>> >invested in their production...
>> so an air conditioner or heat pump might do almost as well...
>except air conditioners and heat pumps have negative cash flows from day 1.
it's all relative, no? both "produce" energy, in a sense. say the heating
alternative is 30k kwh/year of electric resistance at 10 cents/kwh, ie $3k,
and a $200 5000 btu/h window "heat pump" could air-condition the basement
floor and heat the house in wintertime with a 3:1 cop. the ac would only
use 10k kwh, paying for itself economically in $200/$2k/year = 0.1 years.
if the cost of the ac were represented entirely by its embodied energy at
10 cents/kwh, the energy payback would be the same, ie 2kkwh/20kkwh/year
= 0.1 years, for a 10:1 energy return per year, or 100:1 over a 10 year
lifetime.
nick
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