re: wind and solar power aren't just for tree-huggers anymore
4 oct 2002
>>> every kilowatt of capacity has to have an equaivalent amount of backup
>>> in conventional sources...
>>with alternative energy sources, we may need more total overcapacity to
>>provide the same availability, but it needn't be numerically equivalent,
>>especially with a large number of sources.
>the alternative energy sources can't use the backup overcapacity
>already there, because then the overcapacity won't be available for
>the conventional plants' planning...
they can use some in a statistical sense. if we add a 1 mw windmill and
a 1 mw load to the grid, we can maintain the same system availability
with less than 1 mw of "conventional backup."
>>a large enough number of sufficiently diverse alternative sources could
>>provide any specified availability, even with no conventional backup...
>...daylight can't be be used for backup during the night since the
>usa is all night at pretty much the same time, so you atuomatically
>need an equivalent amount of backup.
still too black and white. pv is only one alternative, and energy can
be stored, and "pretty much" isn't "all," and "equivalent" is less
than "numerically equal."
>...although statistically there is usually wind *somewhere* there are
>also times when it's not very windy anywhere, especially at night when
>winds are normally calmest...
"sufficiently diverse" is a matter of numbers and multiple timezones.
>the country can't just go into blackout every now and them just because
>it only happens once or twice a year.
also a matter of numbers. conventional sources fail as well.
>in any case, using other alternative eneryg sources as backup still
>means building up to twice the normally needed capacity.
"up to" isn't the same as "equal," no matter what ax you are grinding :-)