Locrian said:
I think it saves less than one fossil fuel BTU, as the energy used to produce the solar cell likely came from fossil fuel. Or is that such a small amount it is effectively zero? I'd be surprised if that was so.
Thanks Locrian - i see the ambiguity now.
What i had in mind was solar water heating , not solar electricity.
Solar electric panels are maybe 20% (more likely ~10%) so it doesn't make sense to heat water with solar generated electricity. Use that precious electricity for worthwhile stuff like refrigerating your food and playing classical music on your stereo, and enjoying PF...
That FPL plant in the picture uses solar to preheat water that is on its way to a fossil boiler.
It isn't a photoelectric plant. The boiler feeds steam to a turbogenerator.
The mirrors heat a thermal oil to around 400 degrees, and that hot oil preheats the feedwater that's headed for the boiler.
So, in that plant every BTU from solar
is a BTU that doesn't have to be made in the boiler by burning gas or oil.
Same would be true of a rooftop solar water heater.
Every BTU you collect is one BTU that didn't come in through your KWH meter.
In fact a residential heater probably does better than 1::1, big picture.
Since a typical fossil plant is ~40% efficient, every BTU collected on a rooftop water heater is 2.5 BTU's that don't have to be made in electric company's boiler. So your rooftop heater saves 2.5 BTU of fossil fuel for every BTU it collects.
In my opinion that's what we should be doing.
Sorry for the lack of clarity.
Thanks for the observation.
I wonder whether Mr Chu is enough of a home handyman to appreciate this.
I would like to see some practical engineering talent in the cabinet.
We need politicians who change their own motor oil.
old jim