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re: $windpower-energy storage$
1 may 2000
r.h. allen wrote:
>>>the costs of some systems are more dependant upon throughput than
>>>on capacity.
maybe, if "throughput" means "power," ie "energy transfer rate" and
"capacity" means "stored energy capacity," vs the usual way of talking.
>think of it like a battery, where "capacity" generally refers to the
>amount of energy it can store.
ok, eg in a single 100% discharge...
>>>in other words, a pumped hydro system that can move water at a rate
>>>equivalent to 10 kw will cost $5,000 to $16,000 regardless of whether
>>>it has 100 kwh storage capacity or 100 wh storage capacity.
the first system would fill up the "battery" in 10 hours. the second
would fill it in 36 seconds. why would anyone build that one...?
>>sounds like nonsense to me...
>if the pumping system is significantly more expensive than the tanks
>or pool used to store the water, why would it be nonsense?
a 1000:1 difference in storage capacity can make a large difference
in the price of the "battery" and the cost to operate it, if larger
capacities mean more head. one wh is 2654 ft-lb at 100% efficiency,
if i did that right, eg a 6" deep x 1' diameter puddle 100' up; 1 kwh
is a 4' deep x 66' puddle, still not that big, but 10 gwh (overnight
storage for a nuke?) is a 10' deep x 3600' (950 acre) puddle, no?
trojan rates batteries in "lifetime energy units," ie the total amount
of energy that a battery can store over its lifetime. for instance, they
say a t-105 battery can store a total of 438 kwh over its lifetime, ie
that's the depth of discharge times the number of cycles in its lifetime,
so a $65 t-105 stores energy at a cost of $65/438kwh = 14.8 cents/kwh
over its lifetime (unless it lives at george ghio's house, in which case
its life-cycle cost is calculated with feathers and animal entrails :-)
nick
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