Air compressor as energy storage? - Page 7

 

On Fri, 23 Feb 2007 21:00:21 +0000, andrew heggie


Not quite the same, but along similar lines-

Early settlers often relied on "thundermills" for sawing wood or doing
useful work.  These mills were on small streams that only had
sufficient power when the stream was full from winter runoff or heavy
storms, hence (I guess) the name derived from mills that operated when
or after there was thunder in the area.

Later mills often employed multiple dams to store as much of the flash
runoff as possible and to accumulate stream flow into a useful burst
of power.  One grist mill in the town where I grew up had three dams
on the same stream, yet only the lowest dam had a penstock and pelton
wheel.  The upper dams added capacity, but not additional power.  The
storage wasn't pumped, but served a similar purpose to pumped power.

Using otherwise wasted storm runoff to power a pump leading to a
storage pond could be an example of where pumped storage makes sense.
As an example, my stream has a relatively low head, but there is a
nearby area about 60 feet above the stream that could be easily and
fairly inexpensively turned into a pond.  Would it be cost effective?
Probably not for just power, but if irrigation, fire protection, stock
and wildlife watering, augmenting a later low stream flow to help keep
(stocked) fish in a hole in the stream alive, and other possible uses
are figured in, it might make marginal sense.

I can think of other situations, like a microhydro setup below a power
dam with a regular peak use discharge schedule, where utilizing the
heavy flow might be the only practical method of getting sufficient
power.  Would batteries be better for storing it?  Possibly, but a
small side canyon or gully that could be dammed would be very tempting
for pumped storage.  Such a setup would involve a lot of governmental
meddling though, so it might not be worth it from that aspect alone.

Perhaps the key is similar to co-generation, where instead of heat and
power, the symbiots are water and power.  Like this:  :-)

<http://gizmodo.com/gadgets/gadgets/waterpressure-powered-lightup-shower-155266.php>

  On Fri, 23 Feb 2007 17:28:25 -0500, somebody@somewhere.com wrote:


OK I've not come across the same here, though we do have a number of
old tidal impoundment mills, they lead to highly unsocial working
hours.


Well I suspect wildlife and turbines don't go well together but your
points are much the same as mine. I suspect the reaction turbines are
too capital expensive and I haven't any idea how efficient the old
wind powered well pumps are/were but they and pelton wheels are fairly
simple technology. The advantage of a pelton turbine looks like its
ability to follow a synchronous load by simply varying the jet.


On the other hand a modest pond above and below a decent drop may not
suffer too much regulatory interference??

Saves walking into a cold shower :-)

AJH

 

Many of the commercial systems use the same rotary 'device' to pump water
and extract energy from the water.  They often have variable pitch blades
and/or variable blades on the stationary periphery.  I'm not sure, but I
think most don't even reverse direction of rotation, just the blade angle of
attack.  Keep in mind, the large units use synchronous machines, so the RPM
is fixed once they are started.  Using variable blading allows regulation of
flow / power level.

Separate units doubles the capital cost.  Variable blading adds to the cost,
but not nearly as much.

daestrom

 

You do not have a storage lake, you got one lake where water is
drained. (possibly with connecting lakes, but if so, only to maximise
the area where you can collect rain.


Other utilities. Nuclear, coal and hydro-dams that has to produce
because their storage capacity is full or near full. Or even hydro
plants that rely on rivers without dams.


The storage lake and main source is the same thing. You pump the water
from other sources. Possibly collection sites at lower altitudes or
from a lake/river.


The lower the usage of the baseload(minimum supply of electricity) the
lower the price of the electricity gets. If it is not sold(used), it
needs to be "burned of".


Its not free, but the cost of running them is lower than the price you
get when you are using the pumped water to generate electricity at a
later point.

--
SEE YA !!!
Trygve Lillefosse
AKA - Malawi, The Fisher King

 

Not realy. It has a lower cost per kW the more/faster it produces.
I expect that there is some kind of "sweet spot" where the price per
kW is lowest.

If it is shut down for a few hours due to low electricity prices, you
still got salaries. capital costs etc.

--
SEE YA !!!
Trygve Lillefosse
AKA - Malawi, The Fisher King