| Topic: |
Science > Physics |
| User: |
"Fran" |
| Date: |
03 Jun 2007 02:03:03 AM |
| Object: |
Extracting energy from pumped storage |
As people here will know, I've been talking a bit about the efficacy
of seaboard hydro in concert with wind, wave, and tidal energy in
turning these energy capture options into baseload power sources.
I was considering how much energy you'd want to store. A survey of the
coastline of NSW, Australia shows that there are many locations near
towns where, within about 100 metres of the shoreline, the contours
take the land up about 500 feet (about 160 metres) from sea level.
Imagine if one built at the top of this land form a catchment that
looked rather like a y-shaped funnel. The stalk of the funnel could
follow the topography down (or be set in at about 45%) towards the
nearest catchment/water treatment works or pumping station etc.
The open part of the funnel could be 2 km in diameter and rise 300 or
so metres above the bottom valve, which could be about 20 metres in
diameter. A catchment of that size should hold something like 3.6 GL
of water.
At the bottom, in the sea, the wind/marine turbine wave or tidal
devices could supply the power to pump sea water up to the top of the
catchment (about 460 metres up) and fill it.
In the centre of the funnel one could have a large rotating turbine
with vanes obtruding from the centre perhaps 900 metres. On the smooth
walls one could have small turbines mounted.
Then, as the valve at the base was progressively opened, to supply
power, in addition to that generated in the normal way by water
flowing under pressure over turbine mounted in the spill way, one
should also get energy from the whirlpool created as the water begins
to flow around the walls.
As the water reached the bottom of the spillway, it would pass through
RO filters and emerge at the other end as potable grade water, which
could then be supplied for local residential, industrial, agricultural
or other use.
Essentially, the hydro plant would work as a kind of transformer for
the various intermittent devices attached to it, but it would also
solve a secondary problem -- water supply, in an energy-efficient way.
It would obviously also double as an extra catchment for rainwater,
from which power could also be extracted.
It might be of course that a better way of handling the configuration
would be to supply power directly to the grid from the devices when
the energy was good, and top up with hydro when it fell short, and use
the devices to replenish the catchment when more power was being
produced than the grid needed.
Comments?
Fran
.
|
|
| User: "daestrom" |
|
| Title: Re: Extracting energy from pumped storage |
03 Jun 2007 10:05:59 AM |
|
|
"Fran" <Fran.Beta@gmail.com> wrote in message
news:1180854183.156621.311450@j4g2000prf.googlegroups.com...
As people here will know, I've been talking a bit about the efficacy
of seaboard hydro in concert with wind, wave, and tidal energy in
turning these energy capture options into baseload power sources.
I was considering how much energy you'd want to store. A survey of the
coastline of NSW, Australia shows that there are many locations near
towns where, within about 100 metres of the shoreline, the contours
take the land up about 500 feet (about 160 metres) from sea level.
An execellent, fortuitous topography. Such a situation lends itself well to
pumped-storage. But the economics would need to be reviewed.
Imagine if one built at the top of this land form a catchment that
looked rather like a y-shaped funnel. The stalk of the funnel could
follow the topography down (or be set in at about 45%) towards the
nearest catchment/water treatment works or pumping station etc.
The open part of the funnel could be 2 km in diameter and rise 300 or
so metres above the bottom valve, which could be about 20 metres in
diameter. A catchment of that size should hold something like 3.6 GL
of water.
Hmmm.... at 300 meters you're talking a pressure of about 3 MPa. A 20 meter
diameter valve would have a force against it of more than 9.5e8 N. That's
about 97,000 metric tonnes. It may be more practical to split the flow into
multiple smaller diameters and valves. This may also improve performance by
reducing throttleing losses when only partial flow is needed.
At the bottom, in the sea, the wind/marine turbine wave or tidal
devices could supply the power to pump sea water up to the top of the
catchment (about 460 metres up) and fill it.
In the centre of the funnel one could have a large rotating turbine
with vanes obtruding from the centre perhaps 900 metres. On the smooth
walls one could have small turbines mounted.
Then, as the valve at the base was progressively opened, to supply
power, in addition to that generated in the normal way by water
flowing under pressure over turbine mounted in the spill way, one
should also get energy from the whirlpool created as the water begins
to flow around the walls.
I don't think you're going to get that much of a 'whirlpool effect'. Unless
you plan on draining that volume of 3.6 GL in a very rapid manner, there
probably won't be enough of a whirlpool to extract enough energy to ever pay
for the turbines.
As the water reached the bottom of the spillway, it would pass through
RO filters and emerge at the other end as potable grade water, which
could then be supplied for local residential, industrial, agricultural
or other use.
If you mean reverse-osmosis filtration, then you have a problem here.
Typical reverse-osmosis filtration requires the seawater pressure to be 6.8
MPa. Your 300 meter high column of water does not develop that much
pressure. Reverse-osmosis purification of seawater is a rather energy
intensive system.
If a large amount of the available head is diverted to power generation,
then there would be essentially no remaining head for the reverse-osmosis
process. Or vice-versa, after passing through a reverse-osmosis filtration
system, the water would have essentially no head left for power production.
Essentially, the hydro plant would work as a kind of transformer for
the various intermittent devices attached to it, but it would also
solve a secondary problem -- water supply, in an energy-efficient way.
It would obviously also double as an extra catchment for rainwater,
from which power could also be extracted.
It might be of course that a better way of handling the configuration
would be to supply power directly to the grid from the devices when
the energy was good, and top up with hydro when it fell short, and use
the devices to replenish the catchment when more power was being
produced than the grid needed.
Comments?
The idea of using some intermittent form of energy such as wave or tidal to
pump water into a large, high, storage system can be attractive. The
storage volume can 'smooth out' the energy production or shift it time-wise
from times when generation is high to times when demand is high. I'd focus
on that aspect. Your local topography seems well suited for pumped-storage
of large amounts of energy.
daestrom
.
|
|
|
| User: "Fran" |
|
| Title: Re: Extracting energy from pumped storage |
04 Jun 2007 01:18:54 AM |
|
|
On Jun 4, 1:05 am, "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com>
wrote:
"Fran" <Fran.B...@gmail.com> wrote in message
news:1180854183.156621.311450@j4g2000prf.googlegroups.com...
As people here will know, I've been talking a bit about the efficacy
of seaboard hydro in concert with wind, wave, and tidal energy in
turning these energy capture options into baseload power sources.
I was considering how much energy you'd want to store. A survey of the
coastline of NSW, Australia shows that there are many locations near
towns where, within about 100 metres of the shoreline, the contours
take the land up about 500 feet (about 160 metres) from sea level.
Thanks for your thoughtful response.
An excellent, fortuitous topography. Such a situation lends itself well to
pumped-storage. But the economics would need to be reviewed.
Imagine if one built at the top of this land form a catchment that
looked rather like a y-shaped funnel. The stalk of the funnel could
follow the topography down (or be set in at about 45%) towards the
nearest catchment/water treatment works or pumping station etc.
The open part of the funnel could be 2 km in diameter and rise 300 or
so metres above the bottom valve, which could be about 20 metres in
diameter. A catchment of that size should hold something like 3.6 GL
of water.
Hmmm.... at 300 meters you're talking a pressure of about 3 MPa. A 20 meter
diameter valve would have a force against it of more than 9.5e8 N. That's
about 97,000 metric tonnes. It may be more practical to split the flow into
multiple smaller diameters and valves. This may also improve performance by
reducing throttleing losses when only partial flow is needed.
I see.
At the bottom, in the sea, the wind/marine turbine wave or tidal
devices could supply the power to pump sea water up to the top of the
catchment (about 460 metres up) and fill it.
In the centre of the funnel one could have a large rotating turbine
with vanes obtruding from the centre perhaps 900 metres. On the smooth
walls one could have small turbines mounted.
Then, as the valve at the base was progressively opened, to supply
power, in addition to that generated in the normal way by water
flowing under pressure over turbine mounted in the spill way, one
should also get energy from the whirlpool created as the water begins
to flow around the walls.
I don't think you're going to get that much of a 'whirlpool effect'. Unless
you plan on draining that volume of 3.6 GL in a very rapid manner, there
probably won't be enough of a whirlpool to extract enough energy to ever pay
for the turbines.
Hmmm ... what a shame.
As the water reached the bottom of the spillway, it would pass through
RO filters and emerge at the other end as potable grade water, which
could then be supplied for local residential, industrial, agricultural
or other use.
If you mean reverse-osmosis filtration, then you have a problem here.
Typical reverse-osmosis filtration requires the seawater pressure to be 6.8
MPa. Your 300 meter high column of water does not develop that much
pressure. Reverse-osmosis purification of seawater is a rather energy
intensive system.
Odd. I thought it was a good deal less than this.
If a large amount of the available head is diverted to power generation,
then there would be essentially no remaining head for the reverse-osmosis
process. Or vice-versa, after passing through a reverse-osmosis filtration
system, the water would have essentially no head left for power production.
That is a shame, because it negatively affects the economics of the
project. I suppose that's why those wave plants off Port Kembla
deliver either desal or power or some balance between the two.
Essentially, the hydro plant would work as a kind of transformer for
the various intermittent devices attached to it, but it would also
solve a secondary problem -- water supply, in an energy-efficient way.
It would obviously also double as an extra catchment for rainwater,
from which power could also be extracted.
It might be of course that a better way of handling the configuration
would be to supply power directly to the grid from the devices when
the energy was good, and top up with hydro when it fell short, and use
the devices to replenish the catchment when more power was being
produced than the grid needed.
Comments?
The idea of using some intermittent form of energy such as wave or tidal to
pump water into a large, high, storage system can be attractive. The
storage volume can 'smooth out' the energy production or shift it time-wise
from times when generation is high to times when demand is high. I'd focus
on that aspect. Your local topography seems well suited for pumped-storage
of large amounts of energy.
Thanks once again.
I can't help but wonder if there isn't some way to make good use of
the outflows of water once it has passed the head. Perhaps some other
kind of filtration equipment that processed water more slowly might be
indicated. I suppose though you'd then get water backing up unless you
built ... another catchment, hence adding to the expense.
I saw some papers on small hydro, and they commented negatively on the
creation of thermal clines within the system. I don't suppose
something of the dimensions I've outlined could also generate power
using some sort of OTEC-style system in the catchment?
Perhaps the water at the base would not remain steady for long enough
to make much of a thermal cline.
Oh well ... more thought required.
Fran
.
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| User: "Bill Ward" |
|
| Title: Re: Extracting energy from pumped storage |
03 Jun 2007 02:01:48 PM |
|
|
On Sun, 03 Jun 2007 11:05:59 -0400, daestrom wrote:
"Fran" <Fran.Beta@gmail.com> wrote in message
news:1180854183.156621.311450@j4g2000prf.googlegroups.com...
As people here will know, I've been talking a bit about the efficacy of
seaboard hydro in concert with wind, wave, and tidal energy in turning
these energy capture options into baseload power sources.
I was considering how much energy you'd want to store. A survey of the
coastline of NSW, Australia shows that there are many locations near
towns where, within about 100 metres of the shoreline, the contours take
the land up about 500 feet (about 160 metres) from sea level.
An execellent, fortuitous topography. Such a situation lends itself well
to pumped-storage. But the economics would need to be reviewed.
Imagine if one built at the top of this land form a catchment that
looked rather like a y-shaped funnel. The stalk of the funnel could
follow the topography down (or be set in at about 45%) towards the
nearest catchment/water treatment works or pumping station etc.
The open part of the funnel could be 2 km in diameter and rise 300 or so
metres above the bottom valve, which could be about 20 metres in
diameter. A catchment of that size should hold something like 3.6 GL of
water.
Hmmm.... at 300 meters you're talking a pressure of about 3 MPa. A 20
meter diameter valve would have a force against it of more than 9.5e8 N.
That's about 97,000 metric tonnes. It may be more practical to split the
flow into multiple smaller diameters and valves. This may also improve
performance by reducing throttling losses when only partial flow is
needed.
Has anybody ever tried a binary sequence of valves? Or is it too costly
compared to the throttling loss to make it economic?
I always enjoy your posts.
Bill Ward
.
|
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| User: "daestrom" |
|
| Title: Re: Extracting energy from pumped storage |
04 Jun 2007 06:39:49 PM |
|
|
"Bill Ward" <bward@REMOVETHISix.netcom.com> wrote in message
news:pan.2007.06.03.19.01.46.236889@REMOVETHISix.netcom.com...
On Sun, 03 Jun 2007 11:05:59 -0400, daestrom wrote:
"Fran" <Fran.Beta@gmail.com> wrote in message
news:1180854183.156621.311450@j4g2000prf.googlegroups.com...
As people here will know, I've been talking a bit about the efficacy of
seaboard hydro in concert with wind, wave, and tidal energy in turning
these energy capture options into baseload power sources.
I was considering how much energy you'd want to store. A survey of the
coastline of NSW, Australia shows that there are many locations near
towns where, within about 100 metres of the shoreline, the contours take
the land up about 500 feet (about 160 metres) from sea level.
An execellent, fortuitous topography. Such a situation lends itself well
to pumped-storage. But the economics would need to be reviewed.
Imagine if one built at the top of this land form a catchment that
looked rather like a y-shaped funnel. The stalk of the funnel could
follow the topography down (or be set in at about 45%) towards the
nearest catchment/water treatment works or pumping station etc.
The open part of the funnel could be 2 km in diameter and rise 300 or so
metres above the bottom valve, which could be about 20 metres in
diameter. A catchment of that size should hold something like 3.6 GL of
water.
Hmmm.... at 300 meters you're talking a pressure of about 3 MPa. A 20
meter diameter valve would have a force against it of more than 9.5e8 N.
That's about 97,000 metric tonnes. It may be more practical to split the
flow into multiple smaller diameters and valves. This may also improve
performance by reducing throttling losses when only partial flow is
needed.
Has anybody ever tried a binary sequence of valves? Or is it too costly
compared to the throttling loss to make it economic?
To a limited degree, they are used in lots of different applications. Even
high-pressure steam turbines often use a methodology called 'partial-arc'
admission. Basically instead of one large throttle valve, several (four or
more) small ones are used. When partial loading is called for, some of the
valves are left fully shut and the others are 'throttled' to a much wider
opening.
Of course there is a capital cost versus efficiency improvement trade-off to
be considered.
I think in large hydro, if they have to reduce output for water-rationing
reasons (hydro units often have to serve multiple task-masters), they
shutdown some of the individual units and let the others run closer to
full-power. So instead of running 6 units at 50%, they would rather run 3
units at 100%. Of course, this means it could take longer to start up the
idle units, but it also means you can do maintenance on them.
daestrom
I always enjoy your posts.
Thanks...
.
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| User: "Don Kelly" |
|
| Title: Re: Extracting energy from pumped storage |
03 Jun 2007 09:38:34 PM |
|
|
----------------------------
"Fran" <Fran.Beta@gmail.com> wrote in message
news:1180854183.156621.311450@j4g2000prf.googlegroups.com...
As people here will know, I've been talking a bit about the efficacy
of seaboard hydro in concert with wind, wave, and tidal energy in
turning these energy capture options into baseload power sources.
I was considering how much energy you'd want to store. A survey of the
coastline of NSW, Australia shows that there are many locations near
towns where, within about 100 metres of the shoreline, the contours
take the land up about 500 feet (about 160 metres) from sea level.
Imagine if one built at the top of this land form a catchment that
looked rather like a y-shaped funnel. The stalk of the funnel could
follow the topography down (or be set in at about 45%) towards the
nearest catchment/water treatment works or pumping station etc.
The open part of the funnel could be 2 km in diameter and rise 300 or
so metres above the bottom valve, which could be about 20 metres in
diameter. A catchment of that size should hold something like 3.6 GL
of water.
At the bottom, in the sea, the wind/marine turbine wave or tidal
devices could supply the power to pump sea water up to the top of the
catchment (about 460 metres up) and fill it.
In the centre of the funnel one could have a large rotating turbine
with vanes obtruding from the centre perhaps 900 metres. On the smooth
walls one could have small turbines mounted.
Then, as the valve at the base was progressively opened, to supply
power, in addition to that generated in the normal way by water
flowing under pressure over turbine mounted in the spill way, one
should also get energy from the whirlpool created as the water begins
to flow around the walls.
As the water reached the bottom of the spillway, it would pass through
RO filters and emerge at the other end as potable grade water, which
could then be supplied for local residential, industrial, agricultural
or other use.
Essentially, the hydro plant would work as a kind of transformer for
the various intermittent devices attached to it, but it would also
solve a secondary problem -- water supply, in an energy-efficient way.
It would obviously also double as an extra catchment for rainwater,
from which power could also be extracted.
It might be of course that a better way of handling the configuration
would be to supply power directly to the grid from the devices when
the energy was good, and top up with hydro when it fell short, and use
the devices to replenish the catchment when more power was being
produced than the grid needed.
Comments?
Fran
-------------
What you are proposing, forgetting the Y shape which is really doing nothing
beneficial, is huge and horribly expensive. In fact a number of smaller
units with the same total storage capacity would be more practical in many
ways. It would be best to have as much of the storage at as high a head as
possible. A Y will not be the best way to do this. You also want the
generating units at the bottom to take advantage of the full head. There is
no use having a turbine half way up -you then would get rather poor overall
efficiency - Consider what is done in existing pump storage systems which
recover 80% or more of the pumping energy. The designers of these are far
better hydraulic engineers than you or I.
--
Don Kelly
remove the X to answer
.
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| User: "Fran" |
|
| Title: Re: Extracting energy from pumped storage |
04 Jun 2007 12:45:25 AM |
|
|
On Jun 4, 12:38 pm, "Don Kelly" <d...@shaw.ca> wrote:
----------------------------"Fran" <Fran.B...@gmail.com> wrote in message
news:1180854183.156621.311450@j4g2000prf.googlegroups.com...
As people here will know, I've been talking a bit about the efficacy
of seaboard hydro in concert with wind, wave, and tidal energy in
turning these energy capture options into baseload power sources.
I was considering how much energy you'd want to store. A survey of the
coastline of NSW, Australia shows that there are many locations near
towns where, within about 100 metres of the shoreline, the contours
take the land up about 500 feet (about 160 metres) from sea level.
Imagine if one built at the top of this land form a catchment that
looked rather like a y-shaped funnel. The stalk of the funnel could
follow the topography down (or be set in at about 45%) towards the
nearest catchment/water treatment works or pumping station etc.
The open part of the funnel could be 2 km in diameter and rise 300 or
so metres above the bottom valve, which could be about 20 metres in
diameter. A catchment of that size should hold something like 3.6 GL
of water.
At the bottom, in the sea, the wind/marine turbine wave or tidal
devices could supply the power to pump sea water up to the top of the
catchment (about 460 metres up) and fill it.
In the centre of the funnel one could have a large rotating turbine
with vanes obtruding from the centre perhaps 900 metres. On the smooth
walls one could have small turbines mounted.
Then, as the valve at the base was progressively opened, to supply
power, in addition to that generated in the normal way by water
flowing under pressure over turbine mounted in the spill way, one
should also get energy from the whirlpool created as the water begins
to flow around the walls.
As the water reached the bottom of the spillway, it would pass through
RO filters and emerge at the other end as potable grade water, which
could then be supplied for local residential, industrial, agricultural
or other use.
Essentially, the hydro plant would work as a kind of transformer for
the various intermittent devices attached to it, but it would also
solve a secondary problem -- water supply, in an energy-efficient way.
It would obviously also double as an extra catchment for rainwater,
from which power could also be extracted.
It might be of course that a better way of handling the configuration
would be to supply power directly to the grid from the devices when
the energy was good, and top up with hydro when it fell short, and use
the devices to replenish the catchment when more power was being
produced than the grid needed.
Comments?
Fran
-------------
What you are proposing, forgetting the Y shape which is really doing nothing
beneficial, is huge and horribly expensive. In fact a number of smaller
units with the same total storage capacity would be more practical in many
ways.
Wouldn't this increase the surface area, and thus evaporation?
Wouldn't it also add to the cost of construction, increase site
restrictions and so forth?
It would be best to have as much of the storage at as high a head as
possible. A Y will not be the best way to do this. You also want the
generating units at the bottom to take advantage of the full head.
I can see that
There is
no use having a turbine half way up -you then would get rather poor overall
efficiency -
I was thinking of it mainly in the catchment. Clearly, the pressure at
the top of the Y would slow the rate of release, but in the meantime,
some of the water that was in the catchment but not yet in the
spillway would be generating current.
Consider what is done in existing pump storage systems which
recover 80% or more of the pumping energy.
True, but the system is supposed to produce desal as well, and
reducing the pressure would probably be necessary to protect the
filters in this case, would it not?
The designers of these are far
better hydraulic engineers than you or I.
Undoubtedly, which is why I was seeking feedback here on how plausible
it would be.
Fran
.
|
|
|
| User: "daestrom" |
|
| Title: Re: Extracting energy from pumped storage |
04 Jun 2007 06:45:46 PM |
|
|
"Fran" <Fran.Beta@gmail.com> wrote in message
news:1180935925.686947.57420@i13g2000prf.googlegroups.com...
On Jun 4, 12:38 pm, "Don Kelly" <d...@shaw.ca> wrote:
----------------------------"Fran" <Fran.B...@gmail.com> wrote in message
news:1180854183.156621.311450@j4g2000prf.googlegroups.com...
As people here will know, I've been talking a bit about the efficacy
of seaboard hydro in concert with wind, wave, and tidal energy in
turning these energy capture options into baseload power sources.
I was considering how much energy you'd want to store. A survey of the
coastline of NSW, Australia shows that there are many locations near
towns where, within about 100 metres of the shoreline, the contours
take the land up about 500 feet (about 160 metres) from sea level.
Imagine if one built at the top of this land form a catchment that
looked rather like a y-shaped funnel. The stalk of the funnel could
follow the topography down (or be set in at about 45%) towards the
nearest catchment/water treatment works or pumping station etc.
The open part of the funnel could be 2 km in diameter and rise 300 or
so metres above the bottom valve, which could be about 20 metres in
diameter. A catchment of that size should hold something like 3.6 GL
of water.
At the bottom, in the sea, the wind/marine turbine wave or tidal
devices could supply the power to pump sea water up to the top of the
catchment (about 460 metres up) and fill it.
In the centre of the funnel one could have a large rotating turbine
with vanes obtruding from the centre perhaps 900 metres. On the smooth
walls one could have small turbines mounted.
Then, as the valve at the base was progressively opened, to supply
power, in addition to that generated in the normal way by water
flowing under pressure over turbine mounted in the spill way, one
should also get energy from the whirlpool created as the water begins
to flow around the walls.
As the water reached the bottom of the spillway, it would pass through
RO filters and emerge at the other end as potable grade water, which
could then be supplied for local residential, industrial, agricultural
or other use.
Essentially, the hydro plant would work as a kind of transformer for
the various intermittent devices attached to it, but it would also
solve a secondary problem -- water supply, in an energy-efficient way.
It would obviously also double as an extra catchment for rainwater,
from which power could also be extracted.
It might be of course that a better way of handling the configuration
would be to supply power directly to the grid from the devices when
the energy was good, and top up with hydro when it fell short, and use
the devices to replenish the catchment when more power was being
produced than the grid needed.
Comments?
Fran
-------------
What you are proposing, forgetting the Y shape which is really doing
nothing
beneficial, is huge and horribly expensive. In fact a number of smaller
units with the same total storage capacity would be more practical in
many
ways.
Wouldn't this increase the surface area, and thus evaporation?
Wouldn't it also add to the cost of construction, increase site
restrictions and so forth?
It would be best to have as much of the storage at as high a head as
possible. A Y will not be the best way to do this. You also want the
generating units at the bottom to take advantage of the full head.
I can see that
There is
no use having a turbine half way up -you then would get rather poor
overall
efficiency -
I was thinking of it mainly in the catchment. Clearly, the pressure at
the top of the Y would slow the rate of release, but in the meantime,
some of the water that was in the catchment but not yet in the
spillway would be generating current.
How is the waer in the catchment generating current? Your 'whirlpool' idea
won't work. In order to get 'significant' rotary motion, you would need to
drain the water down the 'funnel' much faster then is practical.
Consider what is done in existing pump storage systems which
recover 80% or more of the pumping energy.
True, but the system is supposed to produce desal as well, and
reducing the pressure would probably be necessary to protect the
filters in this case, would it not?
The typical reverse-osmosis filter requires *more* head then your 300
meters, not less. If all the head is used in the generation, none is left
for reverse-osmosis. To get R-O, you would need to boost the head even
further, and none would be left for hydro-generation.
You can't do both at the same time.
daestrom
.
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| User: "Fran" |
|
| Title: Re: Extracting energy from pumped storage |
04 Jun 2007 08:57:58 PM |
|
|
On Jun 5, 9:45 am, "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com>
wrote:
"Fran" <Fran.B...@gmail.com> wrote in message
news:1180935925.686947.57420@i13g2000prf.googlegroups.com...
On Jun 4, 12:38 pm, "Don Kelly" <d...@shaw.ca> wrote:
----------------------------"Fran" <Fran.B...@gmail.com> wrote in message
news:1180854183.156621.311450@j4g2000prf.googlegroups.com...
As people here will know, I've been talking a bit about the efficacy
of seaboard hydro in concert with wind, wave, and tidal energy in
turning these energy capture options into baseload power sources.
I was considering how much energy you'd want to store. A survey of the
coastline of NSW, Australia shows that there are many locations near
towns where, within about 100 metres of the shoreline, the contours
take the land up about 500 feet (about 160 metres) from sea level.
Imagine if one built at the top of this land form a catchment that
looked rather like a y-shaped funnel. The stalk of the funnel could
follow the topography down (or be set in at about 45%) towards the
nearest catchment/water treatment works or pumping station etc.
The open part of the funnel could be 2 km in diameter and rise 300 or
so metres above the bottom valve, which could be about 20 metres in
diameter. A catchment of that size should hold something like 3.6 GL
of water.
At the bottom, in the sea, the wind/marine turbine wave or tidal
devices could supply the power to pump sea water up to the top of the
catchment (about 460 metres up) and fill it.
In the centre of the funnel one could have a large rotating turbine
with vanes obtruding from the centre perhaps 900 metres. On the smooth
walls one could have small turbines mounted.
Then, as the valve at the base was progressively opened, to supply
power, in addition to that generated in the normal way by water
flowing under pressure over turbine mounted in the spill way, one
should also get energy from the whirlpool created as the water begins
to flow around the walls.
As the water reached the bottom of the spillway, it would pass through
RO filters and emerge at the other end as potable grade water, which
could then be supplied for local residential, industrial, agricultural
or other use.
Essentially, the hydro plant would work as a kind of transformer for
the various intermittent devices attached to it, but it would also
solve a secondary problem -- water supply, in an energy-efficient way.
It would obviously also double as an extra catchment for rainwater,
from which power could also be extracted.
It might be of course that a better way of handling the configuration
would be to supply power directly to the grid from the devices when
the energy was good, and top up with hydro when it fell short, and use
the devices to replenish the catchment when more power was being
produced than the grid needed.
Comments?
Fran
-------------
What you are proposing, forgetting the Y shape which is really doing
nothing
beneficial, is huge and horribly expensive. In fact a number of smaller
units with the same total storage capacity would be more practical in
many
ways.
Wouldn't this increase the surface area, and thus evaporation?
Wouldn't it also add to the cost of construction, increase site
restrictions and so forth?
It would be best to have as much of the storage at as high a head as
possible. A Y will not be the best way to do this. You also want the
generating units at the bottom to take advantage of the full head.
I can see that
There is
no use having a turbine half way up -you then would get rather poor
overall
efficiency -
I was thinking of it mainly in the catchment. Clearly, the pressure at
the top of the Y would slow the rate of release, but in the meantime,
some of the water that was in the catchment but not yet in the
spillway would be generating current.
How is the waer in the catchment generating current? Your 'whirlpool' idea
won't work. In order to get 'significant' rotary motion, you would need to
drain the water down the 'funnel' much faster then is practical.
Consider what is done in existing pump storage systems which
recover 80% or more of the pumping energy.
True, but the system is supposed to produce desal as well, and
reducing the pressure would probably be necessary to protect the
filters in this case, would it not?
The typical reverse-osmosis filter requires *more* head then your 300
meters, not less. If all the head is used in the generation, none is left
for reverse-osmosis. To get R-O, you would need to boost the head even
further, and none would be left for hydro-generation.
You can't do both at the same time.
daestrom- Hide quoted text -
- Show quoted text -
Thanks.
I see that now. Still, given that water *supply* is also a problem, I
suppose you could arrange the outflow to go to a local water treatment
plant, fitted to do the kind of high grade desal implied. That would
in turn imply siting the hydro plant somewhere that water was
especially short. Water is especially short in Sydney, and there is a
plan on the books for a desal plant here anyway, so maybe that's the
ticket.
Fran
.
|
|
|
| User: "Don Kelly" |
|
| Title: Re: Extracting energy from pumped storage |
05 Jun 2007 11:16:32 PM |
|
|
OK-pumped storage. A good but not new idea. Cost is a factor. Size is a
factor. In OZ evaporation is a factor. None of these support the funnel idea
(a cylindrical reservoir will have greater storage per unit of
(evaporative)surface area- a bit of geometry shows this). The major thing as
a hydro plant isProper engineering is the major factor and that will
determine the best design.
Direct use of wind, wave and solar power to displace (not replace) other
sources- when such renewable energy is available- is from what I can see,
the best option. It doesn't mean that these other sources can be eliminated
because nature's timetable is not man's. However, IF, the energy available
is in excess of grid demands, then storage can be a viable option.
There are a lot of factors to be considered. One is that hydro generation
from pumped storage is generally short term peaking and as such doesn't
necessarily fit the requirements of a desalinization plant which would
likely be best served by a lower but steady flow through the year. Combining
the two requires a larger capacity desalinization plant that runs part time
and needs extra storage capacity in order to coast through low input
periods.
Pumped storage then is sensible only as far as using excess available grid
energy (including that from renewables) and storing this to be used at
peak demand times. It is not an energy saving system but a cost saving
system- recovering some low fuel cost energy (i.e. solar, nuclear,etc) and
using it to replace high fuel cost plant (i.e. gas turbines) at peak
periods. Pump at 1$/MWh and get 80% of the energy back (at a cost of
1.25$/MWh) when other available sources cost 5$/MWh (of course, if the low
cost energy is directly available at the time then the cost would be 1$/MWH
vs 5$/MWh without the need for the storage which can sit for the next
non-rainy day).
--
Don Kelly
remove the X to answer
----------------------------
"Fran" <Fran.Beta@gmail.com> wrote in message
news:1181008678.699719.69750@n15g2000prd.googlegroups.com...
On Jun 5, 9:45 am, "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com>
wrote:
"Fran" <Fran.B...@gmail.com> wrote in message
news:1180935925.686947.57420@i13g2000prf.googlegroups.com...
On Jun 4, 12:38 pm, "Don Kelly" <d...@shaw.ca> wrote:
----------------------------"Fran" <Fran.B...@gmail.com> wrote in
message
news:1180854183.156621.311450@j4g2000prf.googlegroups.com...
As people here will know, I've been talking a bit about the efficacy
of seaboard hydro in concert with wind, wave, and tidal energy in
turning these energy capture options into baseload power sources.
I was considering how much energy you'd want to store. A survey of
the
coastline of NSW, Australia shows that there are many locations near
towns where, within about 100 metres of the shoreline, the contours
take the land up about 500 feet (about 160 metres) from sea level.
Imagine if one built at the top of this land form a catchment that
looked rather like a y-shaped funnel. The stalk of the funnel could
follow the topography down (or be set in at about 45%) towards the
nearest catchment/water treatment works or pumping station etc.
The open part of the funnel could be 2 km in diameter and rise 300
or
so metres above the bottom valve, which could be about 20 metres in
diameter. A catchment of that size should hold something like 3.6 GL
of water.
At the bottom, in the sea, the wind/marine turbine wave or tidal
devices could supply the power to pump sea water up to the top of
the
catchment (about 460 metres up) and fill it.
In the centre of the funnel one could have a large rotating turbine
with vanes obtruding from the centre perhaps 900 metres. On the
smooth
walls one could have small turbines mounted.
Then, as the valve at the base was progressively opened, to supply
power, in addition to that generated in the normal way by water
flowing under pressure over turbine mounted in the spill way, one
should also get energy from the whirlpool created as the water
begins
to flow around the walls.
As the water reached the bottom of the spillway, it would pass
through
RO filters and emerge at the other end as potable grade water, which
could then be supplied for local residential, industrial,
agricultural
or other use.
Essentially, the hydro plant would work as a kind of transformer for
the various intermittent devices attached to it, but it would also
solve a secondary problem -- water supply, in an energy-efficient
way.
It would obviously also double as an extra catchment for rainwater,
from which power could also be extracted.
It might be of course that a better way of handling the
configuration
would be to supply power directly to the grid from the devices when
the energy was good, and top up with hydro when it fell short, and
use
the devices to replenish the catchment when more power was being
produced than the grid needed.
Comments?
Fran
-------------
What you are proposing, forgetting the Y shape which is really doing
nothing
beneficial, is huge and horribly expensive. In fact a number of
smaller
units with the same total storage capacity would be more practical in
many
ways.
Wouldn't this increase the surface area, and thus evaporation?
Wouldn't it also add to the cost of construction, increase site
restrictions and so forth?
It would be best to have as much of the storage at as high a head as
possible. A Y will not be the best way to do this. You also want the
generating units at the bottom to take advantage of the full head.
I can see that
There is
no use having a turbine half way up -you then would get rather poor
overall
efficiency -
I was thinking of it mainly in the catchment. Clearly, the pressure at
the top of the Y would slow the rate of release, but in the meantime,
some of the water that was in the catchment but not yet in the
spillway would be generating current.
How is the waer in the catchment generating current? Your 'whirlpool'
idea
won't work. In order to get 'significant' rotary motion, you would need
to
drain the water down the 'funnel' much faster then is practical.
Consider what is done in existing pump storage systems which
recover 80% or more of the pumping energy.
True, but the system is supposed to produce desal as well, and
reducing the pressure would probably be necessary to protect the
filters in this case, would it not?
The typical reverse-osmosis filter requires *more* head then your 300
meters, not less. If all the head is used in the generation, none is
left
for reverse-osmosis. To get R-O, you would need to boost the head even
further, and none would be left for hydro-generation.
You can't do both at the same time.
daestrom- Hide quoted text -
- Show quoted text -
Thanks.
I see that now. Still, given that water *supply* is also a problem, I
suppose you could arrange the outflow to go to a local water treatment
plant, fitted to do the kind of high grade desal implied. That would
in turn imply siting the hydro plant somewhere that water was
especially short. Water is especially short in Sydney, and there is a
plan on the books for a desal plant here anyway, so maybe that's the
ticket.
Fran
.
|
|
|
| User: "Fran" |
|
| Title: Re: Extracting energy from pumped storage |
07 Jun 2007 01:26:59 AM |
|
|
On Jun 6, 2:16 pm, "Don Kelly" <d...@shaw.ca> wrote:
OK-pumped storage. A good but not new idea. Cost is a factor. Size is a
factor. In OZ evaporation is a factor. None of these support the funnel idea
(a cylindrical reservoir will have greater storage per unit of
(evaporative)surface area- a bit of geometry shows this).
Oh, I knew this, but I was considering generating power within the
reservoir. If this isn't feasible (on the scale that would make the
trade-off in volume worthwhile), then yes, a cylindrical reservoir
would be better. Then again, an upturned cone would have even less
surface area exposed to the air per unit of mass ... (probably not
justifiable in engineering cost terms though).
The major thing as
a hydro plant isProper engineering is the major factor and that will
determine the best design.
Direct use of wind, wave and solar power to displace (not replace) other
sources- when such renewable energy is available- is from what I can see,
the best option.
Yes, but I was thinking of using the reservoir to provide a better
match with existing power. Since on-demand power is more valuable than
intermittent power, the question arises as to whether the reservoir
adds sufficiently to the value of the wind or wave or solar or tidal
power to justify the extra cost.
It doesn't mean that these other sources can be eliminated
because nature's timetable is not man's. However, IF, the energy available
is in excess of grid demands, then storage can be a viable option.
Frequently, wind turbines have to be "feathered" so as to avoid
overloading the system. If the excess power could be used to refill
the reservoir, and the reservoir's output could be tapered to match
load exactly in close to real time, then in effect, you'd have fully
dispatchable power.
There are a lot of factors to be considered. One is that hydro generation
from pumped storage is generally short term peaking and as such doesn't
necessarily fit the requirements of a desalinization plant which would
likely be best served by a lower but steady flow through the year. Combining
the two requires a larger capacity desalinization plant that runs part time
and needs extra storage capacity in order to coast through low input
periods.
Yes, and in most coastal locations, there is not a huge demand for
desal -- since it rains more frequently. It's inland that the water
tends to be needed. The major cities and their hinterlands are of
course an exception, since the demand for water is huge. On the other
hand, the sources of the water-depleted Darling River system are only
about 400 km from the eastern seaboard. The sources of the Murray are
even closer. These networks of rivers supply irrigation for much of
Australia's agriculture and Adelaide. The Murray also supplies Hydro
power. Right now governments are choosing between environmental flows,
town water and power.
You could make an argument for piping desal to the sources of these
rivers, providing you could do it cheaply enough (dollars and energy),
and providing it was funded by good cost recovery by users. Here,
intermittency wouldn't be a problem.
Pumped storage then is sensible only as far as using excess available grid
energy (including that from renewables) and storing this to be used at
peak demand times. It is not an energy saving system but a cost saving
system- recovering some low fuel cost energy (i.e. solar, nuclear,etc) and
using it to replace high fuel cost plant (i.e. gas turbines) at peak
periods. Pump at 1$/MWh and get 80% of the energy back (at a cost of
1.25$/MWh) when other available sources cost 5$/MWh (of course, if the low
cost energy is directly available at the time then the cost would be 1$/MWH
vs 5$/MWh without the need for the storage which can sit for the next
non-rainy day).
--
I'm not sure about the costings here. Yes, you lose about 20% of the
power, (but since you were dumping all that energy it's moot).
Moreover, if the catchment is rained on, you get some extra water
in.
More to the point, you avoid having baseload cover, and spinning
reserve, and can tailor the transmission and delivery system to the
nameplate specifications of the plant. Since the *marginal* cost of
producing power from wind, wave and hydro is low, you can use it as
baseload or peaking. So you can replace baseload with it, which, as
currently configured, you can't. That in turn affects the economics of
an operation such as this, since, if you can promise and deliver a
certain quantum of power on demand, you cna negotiuate a longterm
price, and that means that you're more likely to get low cost loans,
state support etc.
Fran
Don Kelly
remove the X to answer
----------------------------"Fran" <Fran.B...@gmail.com> wrote in message
news:1181008678.699719.69750@n15g2000prd.googlegroups.com...
On Jun 5, 9:45 am, "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com>
wrote:
"Fran" <Fran.B...@gmail.com> wrote in message
news:1180935925.686947.57420@i13g2000prf.googlegroups.com...
On Jun 4, 12:38 pm, "Don Kelly" <d...@shaw.ca> wrote:
----------------------------"Fran" <Fran.B...@gmail.com> wrote in
message
news:1180854183.156621.311450@j4g2000prf.googlegroups.com...
As people here will know, I've been talking a bit about the efficacy
of seaboard hydro in concert with wind, wave, and tidal energy in
turning these energy capture options into baseload power sources.
I was considering how much energy you'd want to store. A survey of
the
coastline of NSW, Australia shows that there are many locations near
towns where, within about 100 metres of the shoreline, the contours
take the land up about 500 feet (about 160 metres) from sea level.
Imagine if one built at the top of this land form a catchment that
looked rather like a y-shaped funnel. The stalk of the funnel could
follow the topography down (or be set in at about 45%) towards the
nearest catchment/water treatment works or pumping station etc.
The open part of the funnel could be 2 km in diameter and rise 300
or
so metres above the bottom valve, which could be about 20 metres in
diameter. A catchment of that size should hold something like 3.6 GL
of water.
At the bottom, in the sea, the wind/marine turbine wave or tidal
devices could supply the power to pump sea water up to the top of
the
catchment (about 460 metres up) and fill it.
In the centre of the funnel one could have a large rotating turbine
with vanes obtruding from the centre perhaps 900 metres. On the
smooth
walls one could have small turbines mounted.
Then, as the valve at the base was progressively opened, to supply
power, in addition to that generated in the normal way by water
flowing under pressure over turbine mounted in the spill way, one
should also get energy from the whirlpool created as the water
begins
to flow around the walls.
As the water reached the bottom of the spillway, it would pass
through
RO filters and emerge at the other end as potable grade water, which
could then be supplied for local residential, industrial,
agricultural
or other use.
Essentially, the hydro plant would work as a kind of transformer for
the various intermittent devices attached to it, but it would also
solve a secondary problem -- water supply, in an energy-efficient
way.
It would obviously also double as an extra catchment for rainwater,
from which power could also be extracted.
It might be of course that a better way of handling the
configuration
would be to supply power directly to the grid from the devices when
the energy was good, and top up with hydro when it fell short, and
use
the devices to replenish the catchment when more power was being
produced than the grid needed.
Comments?
Fran
-------------
What you are proposing, forgetting the Y shape which is really doing
nothing
beneficial, is huge and horribly expensive. In fact a number of
smaller
units with the same total storage capacity would be more practical in
many
ways.
Wouldn't this increase the surface area, and thus evaporation?
Wouldn't it also add to the cost of construction, increase site
restrictions and so forth?
It would be best to have as much of the storage at as high a head as
possible. A Y will not be the best way to do this. You also want the
generating units at the bottom to take advantage of the full head.
I can see that
There is
no use having a turbine half way up -you then would get rather poor
overall
efficiency -
I was thinking of it mainly in the catchment. Clearly, the pressure at
the top of the Y would slow the rate of release, but in the meantime,
some of the water that was in the catchment but not yet in the
spillway would be generating current.
How is the waer in the catchment generating current? Your 'whirlpool'
idea
won't work. In order to get 'significant' rotary motion, you would need
to
drain the water down the 'funnel' much faster then is practical.
Consider what is done in existing pump storage systems which
recover 80% or more of the pumping energy.
True, but the system is supposed to produce desal as well, and
reducing the pressure would probably be necessary to protect the
filters in this case, would it not?
The typical reverse-osmosis filter requires *more* head then your 300
meters, not less. If all the head is used in the generation, none is
left
for reverse-osmosis. To get R-O, you would need to boost the head even
further, and none would be left for hydro-generation.
You can't do both at the same time.
daestrom- Hide quoted text -
- Show quoted text -
Thanks.
I see that now. Still, given that water *supply* is also a problem, I
suppose you could arrange the outflow to go to a local water treatment
plant, fitted to do the kind of high grade desal implied. That would
in turn imply siting the hydro plant somewhere that water was
especially short. Water is especially short in Sydney, and there is a
plan on the books for a desal plant here anyway, so maybe that's the
ticket.
Fran- Hide quoted text -
- Show quoted text -
.
|
|
|
| User: "Don Kelly" |
|
| Title: Re: Extracting energy from pumped storage |
07 Jun 2007 11:00:56 PM |
|
|
"Fran" <Fran.Beta@gmail.com> wrote in message
news:1181197619.938430.178110@q19g2000prn.googlegroups.com...
On Jun 6, 2:16 pm, "Don Kelly" <d...@shaw.ca> wrote:
OK-pumped storage. A good but not new idea. Cost is a factor. Size is a
factor. In OZ evaporation is a factor. None of these support the funnel
idea
(a cylindrical reservoir will have greater storage per unit of
(evaporative)surface area- a bit of geometry shows this).
Oh, I knew this, but I was considering generating power within the
reservoir. If this isn't feasible (on the scale that would make the
trade-off in volume worthwhile), then yes, a cylindrical reservoir
would be better. Then again, an upturned cone would have even less
surface area exposed to the air per unit of mass ... (probably not
justifiable in engineering cost terms though).
----------
Cone open at top? same exposure for less mass than a cylinder and more rapid
drop in head. Cone open at bottom? less exposure than the other way around
but again head problems and the upper part would be all but useless.
Which?
---------------------
The major thing as
a hydro plant isProper engineering is the major factor and that will
determine the best design.
Direct use of wind, wave and solar power to displace (not replace)
other
sources- when such renewable energy is available- is from what I can see,
the best option.
Yes, but I was thinking of using the reservoir to provide a better
match with existing power. Since on-demand power is more valuable than
intermittent power, the question arises as to whether the reservoir
adds sufficiently to the value of the wind or wave or solar or tidal
power to justify the extra cost.
It doesn't mean that these other sources can be eliminated
because nature's timetable is not man's. However, IF, the energy
available
is in excess of grid demands, then storage can be a viable option.
Frequently, wind turbines have to be "feathered" so as to avoid
overloading the system. If the excess power could be used to refill
the reservoir, and the reservoir's output could be tapered to match
load exactly in close to real time, then in effect, you'd have fully
dispatchable power.
--------
To avoid overloading the system??? In any realistic system nowadays, the
wind power is about 10% of demand - and even if larger at times, the other
generation is backed off.
To avoid overloading the individual wind turbine under high wind conditions
is the more common reason- this won't change.
----
There are a lot of factors to be considered. One is that hydro generation
from pumped storage is generally short term peaking and as such doesn't
necessarily fit the requirements of a desalinization plant which would
likely be best served by a lower but steady flow through the year.
Combining
the two requires a larger capacity desalinization plant that runs part
time
and needs extra storage capacity in order to coast through low input
periods.
Yes, and in most coastal locations, there is not a huge demand for
desal -- since it rains more frequently. It's inland that the water
tends to be needed. The major cities and their hinterlands are of
course an exception, since the demand for water is huge. On the other
hand, the sources of the water-depleted Darling River system are only
about 400 km from the eastern seaboard. The sources of the Murray are
even closer. These networks of rivers supply irrigation for much of
Australia's agriculture and Adelaide. The Murray also supplies Hydro
power. Right now governments are choosing between environmental flows,
town water and power.
--------
And there are conflicts between these usages.
-----
You could make an argument for piping desal to the sources of these
rivers, providing you could do it cheaply enough (dollars and energy),
and providing it was funded by good cost recovery by users. Here,
intermittency wouldn't be a problem.
------
Such arguments are somewhat questionable. If you want desal for agriculture
or for cities, then deliver it directly to where it is needed. Using energy
to desalinate water and then pump it upstream to dump into an existing river
seems more wishful than practical thinking.
---------
Pumped storage then is sensible only as far as using excess available
grid
energy (including that from renewables) and storing this to be used at
peak demand times. It is not an energy saving system but a cost saving
system- recovering some low fuel cost energy (i.e. solar, nuclear,etc)
and
using it to replace high fuel cost plant (i.e. gas turbines) at peak
periods. Pump at 1$/MWh and get 80% of the energy back (at a cost of
1.25$/MWh) when other available sources cost 5$/MWh (of course, if the
low
cost energy is directly available at the time then the cost would be
1$/MWH
vs 5$/MWh without the need for the storage which can sit for the next
non-rainy day).
--
I'm not sure about the costings here. Yes, you lose about 20% of the
power, (but since you were dumping all that energy it's moot).
Moreover, if the catchment is rained on, you get some extra water
in.
---------
Dumping what energy? If you mean "not gathering" energy -OK but the whole
idea is that you take cheap energy to pump and use it when available energy
costs are higher. The costings are illustrative of the point and actual
costs are dependent on the plant and its location. If you do not recover the
cost of pumping (including capital costs) then there is economically no
point.
If you have renewable sources you are best off using them when available.
Pumped storage comes into play if there is excess, relatively cheap,
capacity which can be used for pumping and storage for other times. If there
is no excess of such generation over load demands- then no pumping is done.
More to the point, you avoid having baseload cover, and spinning
reserve, and can tailor the transmission and delivery system to the
nameplate specifications of the plant. Since the *marginal* cost of
producing power from wind, wave and hydro is low, you can use it as
baseload or peaking. So you can replace baseload with it, which, as
currently configured, you can't. That in turn affects the economics of
an operation such as this, since, if you can promise and deliver a
certain quantum of power on demand, you cna negotiuate a longterm
price, and that means that you're more likely to get low cost loans,
state support etc.
-----
You do not avoid baseload cover or spinning reserve. Wind as baseload
requires it to be available all the time. Wind, tidal and solar energy
aren't. Wind as peaking may or may not be available when it is needed so it
doesn't eliminate the need for spinning reserve. Similarly with solar and
wave power. Hydro- depends on the plant and reervoir capacity as to its use
for base or peaking. Pumped storage with wind, solar or wave helps and may
help to firm up the energy that can be promised but power on demand does
mean exactly that- on demand- not when the wind is blowing or the tides are
rising or the sun is out but as demanded. Storage helps here- but only in
that cheap energy is being stored to replace more expensive energy.
Again there is a balance between the various sources but either peaking or
base load usage is not an option for plant which has variability beyond our
control. What is the option is to make the maximum use of such sources when
they are available. While this doesn't eliminate the need for spinning
reserve, it does allow energy storage in the form of unused fuel or water
behind a dam. Every KWh from wind saves a KWh from coal or oil. In that
sense it is a form of storage.
--
Don Kelly
remove the X to answer
----------------------------
Fran
Don Kelly
remove the X to answer
----------------------------"Fran" <Fran.B...@gmail.com> wrote in message
news:1181008678.699719.69750@n15g2000prd.googlegroups.com...
On Jun 5, 9:45 am, "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com>
wrote:
"Fran" <Fran.B...@gmail.com> wrote in message
news:1180935925.686947.57420@i13g2000prf.googlegroups.com...
On Jun 4, 12:38 pm, "Don Kelly" <d...@shaw.ca> wrote:
----------------------------"Fran" <Fran.B...@gmail.com> wrote in
message
news:1180854183.156621.311450@j4g2000prf.googlegroups.com...
As people here will know, I've been talking a bit about the
efficacy
of seaboard hydro in concert with wind, wave, and tidal energy in
turning these energy capture options into baseload power sources.
I was considering how much energy you'd want to store. A survey
of
the
coastline of NSW, Australia shows that there are many locations
near
towns where, within about 100 metres of the shoreline, the
contours
take the land up about 500 feet (about 160 metres) from sea
level.
Imagine if one built at the top of this land form a catchment
that
looked rather like a y-shaped funnel. The stalk of the funnel
could
follow the topography down (or be set in at about 45%) towards
the
nearest catchment/water treatment works or pumping station etc.
The open part of the funnel could be 2 km in diameter and rise
300
or
so metres above the bottom valve, which could be about 20 metres
in
diameter. A catchment of that size should hold something like 3.6
GL
of water.
At the bottom, in the sea, the wind/marine turbine wave or tidal
devices could supply the power to pump sea water up to the top of
the
catchment (about 460 metres up) and fill it.
In the centre of the funnel one could have a large rotating
turbine
with vanes obtruding from the centre perhaps 900 metres. On the
smooth
walls one could have small turbines mounted.
Then, as the valve at the base was progressively opened, to
supply
power, in addition to that generated in the normal way by water
flowing under pressure over turbine mounted in the spill way, one
should also get energy from the whirlpool created as the water
begins
to flow around the walls.
As the water reached the bottom of the spillway, it would pass
through
RO filters and emerge at the other end as potable grade water,
which
could then be supplied for local residential, industrial,
agricultural
or other use.
Essentially, the hydro plant would work as a kind of transformer
for
the various intermittent devices attached to it, but it would
also
solve a secondary problem -- water supply, in an energy-efficient
way.
It would obviously also double as an extra catchment for
rainwater,
from which power could also be extracted.
It might be of course that a better way of handling the
configuration
would be to supply power directly to the grid from the devices
when
the energy was good, and top up with hydro when it fell short,
and
use
the devices to replenish the catchment when more power was being
produced than the grid needed.
Comments?
Fran
-------------
What you are proposing, forgetting the Y shape which is really
doing
nothing
beneficial, is huge and horribly expensive. In fact a number of
smaller
units with the same total storage capacity would be more practical
in
many
ways.
Wouldn't this increase the surface area, and thus evaporation?
Wouldn't it also add to the cost of construction, increase site
restrictions and so forth?
It would be best to have as much of the storage at as high a head
as
possible. A Y will not be the best way to do this. You also want
the
generating units at the bottom to take advantage of the full head.
I can see that
There is
no use having a turbine half way up -you then would get rather poor
overall
efficiency -
I was thinking of it mainly in the catchment. Clearly, the pressure
at
the top of the Y would slow the rate of release, but in the
meantime,
some of the water that was in the catchment but not yet in the
spillway would be generating current.
How is the waer in the catchment generating current? Your 'whirlpool'
idea
won't work. In order to get 'significant' rotary motion, you would
need
to
drain the water down the 'funnel' much faster then is practical.
Consider what is done in existing pump storage systems which
recover 80% or more of the pumping energy.
True, but the system is supposed to produce desal as well, and
reducing the pressure would probably be necessary to protect the
filters in this case, would it not?
The typical reverse-osmosis filter requires *more* head then your 300
meters, not less. If all the head is used in the generation, none is
left
for reverse-osmosis. To get R-O, you would need to boost the head
even
further, and none would be left for hydro-generation.
You can't do both at the same time.
daestrom- Hide quoted text -
- Show quoted text -
Thanks.
I see that now. Still, given that water *supply* is also a problem, I
suppose you could arrange the outflow to go to a local water treatment
plant, fitted to do the kind of high grade desal implied. That would
in turn imply siting the hydro plant somewhere that water was
especially short. Water is especially short in Sydney, and there is a
plan on the books for a desal plant here anyway, so maybe that's the
ticket.
Fran- Hide quoted text -
- Show quoted text -
.
|
|
|
| User: "Fran" |
|
| Title: Re: Extracting energy from pumped storage |
08 Jun 2007 01:28:01 AM |
|
|
On Jun 8, 2:00 pm, "Don Kelly" <d...@shaw.ca> wrote:
"Fran" <Fran.B...@gmail.com> wrote in message
news:1181197619.938430.178110@q19g2000prn.googlegroups.com...> On Jun 6, 2:16 pm, "Don Kelly" <d...@shaw.ca> wrote:
OK-pumped storage. A good but not new idea. Cost is a factor. Size is a
factor. In OZ evaporation is a factor. None of these support the funnel
idea
(a cylindrical reservoir will have greater storage per unit of
(evaporative)surface area- a bit of geometry shows this).
Oh, I knew this, but I was considering generating power within the
reservoir. If this isn't feasible (on the scale that would make the
trade-off in volume worthwhile), then yes, a cylindrical reservoir
would be better. Then again, an upturned cone would have even less
surface area exposed to the air per unit of mass ... (probably not
justifiable in engineering cost terms though).
----------
Cone open at top? same exposure for less mass than a cylinder and more rapid
drop in head. Cone open at bottom? less exposure than the other way around
but again head problems and the upper part would be all but useless.
Which?
---------------------
Sort of like a scientific flask. You would reduce the surface area per
unit of mass, and your other objection sounds reasonable. And of
course, you'd collect less rain.
The major thing as
a hydro plant isProper engineering is the major factor and that will
determine the best design.
Direct use of wind, wave and solar power to displace (not replace)
other
sources- when such renewable energy is available- is from what I can see,
the best option.
Yes, but I was thinking of using the reservoir to provide a better
match with existing power. Since on-demand power is more valuable than
intermittent power, the question arises as to whether the reservoir
adds sufficiently to the value of the wind or wave or solar or tidal
power to justify the extra cost.
It doesn't mean that these other sources can be eliminated
because nature's timetable is not man's. However, IF, the energy
available
is in excess of grid demands, then storage can be a viable option.
Frequently, wind turbines have to be "feathered" so as to avoid
overloading the system. If the excess power could be used to refill
the reservoir, and the reservoir's output could be tapered to match
load exactly in close to real time, then in effect, you'd have fully
dispatchable power.
--------
To avoid overloading the system??? In any realistic system nowadays, the
wind power is about 10% of demand - and even if larger at times, the other
generation is backed off.
How quickly can this be done? As I understand it, It takes a couple of
hours to wind it back.
To avoid overloading the individual wind turbine under high wind conditions
is the more common reason- this won't change.
----
Perhaps not so relevant if you have the kinds of turbine they were
talking about at Nantucket -- a swept area of 172 feet turning out 3.6
MW.
There are a lot of factors to be considered. One is that hydro generation
from pumped storage is generally short term peaking and as such doesn't
necessarily fit the requirements of a desalinization plant which would
likely be best served by a lower but steady flow through the year.
Combining
the two requires a larger capacity desalinization plant that runs part
time
and needs extra storage capacity in order to coast through low input
periods.
Yes, and in most coastal locations, there is not a huge demand for
desal -- since it rains more frequently. It's inland that the water
tends to be needed. The major cities and their hinterlands are of
course an exception, since the demand for water is huge. On the other
hand, the sources of the water-depleted Darling River system are only
about 400 km from the eastern seaboard. The sources of the Murray are
even closer. These networks of rivers supply irrigation for much of
Australia's agriculture and Adelaide. The Murray also supplies Hydro
power. Right now governments are choosing between environmental flows,
town water and power.
--------
And there are conflicts between these usages.
Precisely
-----
You could make an argument for piping desal to the sources of these
rivers, providing you could do it cheaply enough (dollars and energy),
and providing it was funded by good cost recovery by users. Here,
intermittency wouldn't be a problem.
------
Such arguments are somewhat questionable. If you want desal for agriculture
or for cities, then deliver it directly to where it is needed. Using energy
to desalinate water and then pump it upstream
NOT UPSTREAM!! To the source.
to dump into an existing river
seems more wishful than practical thinking.
---------
It depends on how much people are prepared to pay for water, doesn't
it? Right now, water rights are to be cancelled because allocations
can't be met. If you could supply water on demand, then, like any
other commodity, there would be a price. You could tender for the
right to withdraw from the river. You'd pay more, but at least you'd
know that your business plan could never fail for want of water. Some
crops really only pay if you can sustain them for a decade.
Pipes would be more efficient than using the river system for
transport, but then, they cost more, eventually leak, and can't
receive rain. And of course, reasons for putting the water into the
river include environmental flows, preventing algal blooms and so
forth. If you get the primary users to carry the bulk of the
infrastructure burden, the community as a whole can carry the rest.
Providing you're not chewing through non-renewable energy to do this,
the real cost to the provider of the desal is essentially debt service
and recurrent maintenance. And sooner or later, when it does rain
enough to fill the river system with less input from the provider, the
power can be diverted to the grid.
Pumped storage then is sensible only as far as using excess available
grid
energy (including that from renewables) and storing this to be used at
peak demand times. It is not an energy saving system but a cost saving
system- recovering some low fuel cost energy (i.e. solar, nuclear,etc)
and
using it to replace high fuel cost plant (i.e. gas turbines) at peak
periods. Pump at 1$/MWh and get 80% of the energy back (at a cost of
1.25$/MWh) when other available sources cost 5$/MWh (of course, if the
low
cost energy is directly available at the time then the cost would be
1$/MWH
vs 5$/MWh without the need for the storage which can sit for the next
non-rainy day).
--
I'm not sure about the costings here. Yes, you lose about 20% of the
power, (but since you were dumping all that energy it's moot).
Moreover, if the catchment is rained on, you get some extra water
in.
---------
Dumping what energy? If you mean "not gathering" energy
I did.
OK but the whole
idea is that you take cheap energy to pump and use it when available energy
costs are higher. The costings are illustrative of the point and actual
costs are dependent on the plant and its location. If you do not recover the
cost of pumping (including capital costs) then there is economically no
point.
If you have renewable sources you are best off using them when available.
Agreed, providing you can supply the energy in a form and quantum and
time window that is close to optimal.
Pumped storage comes into play if there is excess, relatively cheap,
capacity which can be used for pumping and storage for other times. If there
is no excess of such generation over load demands- then no pumping is done.
More to the point, you avoid having baseload cover, and spinning
reserve, and can tailor the transmission and delivery system to the
nameplate specifications of the plant. Since the *marginal* cost of
producing power from wind, wave and hydro is low, you can use it as
baseload or peaking. So you can replace baseload with it, which, as
currently configured, you can't. That in turn affects the economics of
an operation such as this, since, if you can promise and deliver a
certain quantum of power on demand, you cna negotiuate a longterm
price, and that means that you're more likely to get low cost loans,
state support etc.
-----
You do not avoid baseload cover or spinning reserve. Wind as baseload
requires it to be available all the time. Wind, tidal and solar energy
aren't. Wind as peaking may or may not be available when it is needed so it
doesn't eliminate the need for spinning reserve. Similarly with solar and
wave power. Hydro- depends on the plant and reervoir capacity as to its use
for base or peaking. Pumped storage with wind, solar or wave helps and may
help to firm up the energy that can be promised but power on demand does
mean exactly that- on demand- not when the wind is blowing or the tides are
rising or the sun is out but as demanded. Storage helps here- but only in
that cheap energy is being stored to replace more expensive energy.
Again there is a balance between the various sources but either peaking or
base load usage is not an option for plant which has variability beyond our
control. What is the option is to make the maximum use of such sources when
they are available. While this doesn't eliminate the need for spinning
reserve, it does allow energy storage in the form of unused fuel or water
behind a dam. Every KWh from wind saves a KWh from coal or oil. In that
sense it is a form of storage.
I take your point but I suppose what I'm trying to envisage is some
practicable means in which one could replace ads nearly as possible
100% of the usual baseload sources with wind, solar, wave, tidal etc.
Perhaps there is no such means, but I'd be prepared to wear quite a
bit of redundant capacity and notional inefficiency to do it.
Fran
.
|
|
|
| User: "Don Kelly" |
|
| Title: Re: Extracting energy from pumped storage |
08 Jun 2007 10:12:05 PM |
|
|
"Fran" <Fran.Beta@gmail.com> wrote in message
news:1181284081.466062.121560@g37g2000prf.googlegroups.com...
On Jun 8, 2:00 pm, "Don Kelly" <d...@shaw.ca> wrote:
"Fran" <Fran.B...@gmail.com> wrote in message
news:1181197619.938430.178110@q19g2000prn.googlegroups.com...> On Jun 6,
2:16 pm, "Don Kelly" <d...@shaw.ca> wrote:
OK-pumped storage. A good but not new idea. Cost is a factor. Size is
a
factor. In OZ evaporation is a factor. None of these support the
funnel
idea
(a cylindrical reservoir will have greater storage per unit of
(evaporative)surface area- a bit of geometry shows this).
Oh, I knew this, but I was considering generating power within the
reservoir. If this isn't feasible (on the scale that would make the
trade-off in volume worthwhile), then yes, a cylindrical reservoir
would be better. Then again, an upturned cone would have even less
surface area exposed to the air per unit of mass ... (probably not
justifiable in engineering cost terms though).
----------
Cone open at top? same exposure for less mass than a cylinder and more
rapid
drop in head. Cone open at bottom? less exposure than the other way
around
but again head problems and the upper part would be all but useless.
Which?
---------------------
Sort of like a scientific flask. You would reduce the surface area per
unit of mass, and your other objection sounds reasonable. And of
course, you'd collect less rain.
The major thing as
a hydro plant isProper engineering is the major factor and that will
determine the best design.
Direct use of wind, wave and solar power to displace (not replace)
other
sources- when such renewable energy is available- is from what I can
see,
the best option.
Yes, but I was thinking of using the reservoir to provide a better
match with existing power. Since on-demand power is more valuable than
intermittent power, the question arises as to whether the reservoir
adds sufficiently to the value of the wind or wave or solar or tidal
power to justify the extra cost.
It doesn't mean that these other sources can be eliminated
because nature's timetable is not man's. However, IF, the energy
available
is in excess of grid demands, then storage can be a viable option.
Frequently, wind turbines have to be "feathered" so as to avoid
overloading the system. If the excess power could be used to refill
the reservoir, and the reservoir's output could be tapered to match
load exactly in close to real time, then in effect, you'd have fully
dispatchable power.
--------
To avoid overloading the system??? In any realistic system nowadays, the
wind power is about 10% of demand - and even if larger at times, the
other
generation is backed off.
How quickly can this be done? As I understand it, It takes a couple of
hours to wind it back.
----------------
Depends on the plant- it certainly should be a lot faster than that even
for nuclear (several seconds to a minute or so. Existing hydro and fossil
plant should react withing half a second to two minutes( some hydro is
limited in its response due to penstock "water hammer" problems but these
can be overcome (and generally are). Remember that the existing plant has to
cope with load variations and sometimes these can be drastic changes.
Existing plant also has to cope with the sudden loss of major plant. Sudden
changes in wind availability may exist but these are not so large and
widespread as to cause problems. Solar and tidal is quite predictable.
To avoid overloading the individual wind turbine under high wind
conditions
is the more common reason- this won't change.
----
Perhaps not so relevant if you have the kinds of turbine they were
talking about at Nantucket -- a swept area of 172 feet turning out 3.6
MW.
----------
What makes you think that this is not relevant? The effect of such a unit on
the system is pretty miniscule but the effect on the unit-mechanical stress
etc is rather important.
------------
There are a lot of factors to be considered. One is that hydro
generation
from pumped storage is generally short term peaking and as such
doesn't
necessarily fit the requirements of a desalinization plant which would
likely be best served by a lower but steady flow through the year.
Combining
the two requires a larger capacity desalinization plant that runs part
time
and needs extra storage capacity in order to coast through low input
periods.
Yes, and in most coastal locations, there is not a huge demand for
desal -- since it rains more frequently. It's inland that the water
tends to be needed. The major cities and their hinterlands are of
course an exception, since the demand for water is huge. On the other
hand, the sources of the water-depleted Darling River system are only
about 400 km from the eastern seaboard. The sources of the Murray are
even closer. These networks of rivers supply irrigation for much of
Australia's agriculture and Adelaide. The Murray also supplies Hydro
power. Right now governments are choosing between environmental flows,
town water and power.
--------
And there are conflicts between these usages.
Precisely
-----
You could make an argument for piping desal to the sources of these
rivers, providing you could do it cheaply enough (dollars and energy),
and providing it was funded by good cost recovery by users. Here,
intermittency wouldn't be a problem.
------
Such arguments are somewhat questionable. If you want desal for
agriculture
or for cities, then deliver it directly to where it is needed. Using
energy
to desalinate water and then pump it upstream
NOT UPSTREAM!! To the source.
---------
What is the source? "pumping" implies some lifting of water to a higher
elevation.
to dump into an existing river
seems more wishful than practical thinking.
---------
It depends on how much people are prepared to pay for water, doesn't
it? Right now, water rights are to be cancelled because allocations
can't be met. If you could supply water on demand, then, like any
other commodity, there would be a price. You could tender for the
right to withdraw from the river. You'd pay more, but at least you'd
know that your business plan could never fail for want of water. Some
crops really only pay if you can sustain them for a decade.
Pipes would be more efficient than using the river system for
transport, but then, they cost more, eventually leak, and can't
receive rain. And of course, reasons for putting the water into the
river include environmental flows, preventing algal blooms and so
forth. If you get the primary users to carry the bulk of the
infrastructure burden, the community as a whole can carry the rest.
Providing you're not chewing through non-renewable energy to do this,
the real cost to the provider of the desal is essentially debt service
and recurrent maintenance. And sooner or later, when it does rain
enough to fill the river system with less input from the provider, the
power can be diverted to the grid.
---------
You are trying to combine two independent problems.
a) problems with water supply- what is the best way to satisfy the various
needs for fresh water.?
Desalinization and pumping as you suggest are a part of this that requires
electrical energy.
b) How the energy is obtained and the part of renewables in this process.
The only relationship between the two is that b feeds the grid and a is part
of the grid load.
a) is part of the energy needs independently of the available sources.
b)Comes down to the best allotment of resources to meet the needs and this
is where any consideration of renewables and pumped storage come into play.
Pumped storage then is sensible only as far as using excess available
grid
energy (including that from renewables) and storing this to be used
at
peak demand times. It is not an energy saving system but a cost saving
system- recovering some low fuel cost energy (i.e. solar, nuclear,etc)
and
using it to replace high fuel cost plant (i.e. gas turbines) at peak
periods. Pump at 1$/MWh and get 80% of the energy back (at a cost of
1.25$/MWh) when other available sources cost 5$/MWh (of course, if the
low
cost energy is directly available at the time then the cost would be
1$/MWH
vs 5$/MWh without the need for the storage which can sit for the next
non-rainy day).
--
I'm not sure about the costings here. Yes, you lose about 20% of the
power, (but since you were dumping all that energy it's moot).
Moreover, if the catchment is rained on, you get some extra water
in.
---------
Dumping what energy? If you mean "not gathering" energy
I did.
OK but the whole
idea is that you take cheap energy to pump and use it when available
energy
costs are higher. The costings are illustrative of the point and actual
costs are dependent on the plant and its location. If you do not recover
the
cost of pumping (including capital costs) then there is economically no
point.
If you have renewable sources you are best off using them when available.
Agreed, providing you can supply the energy in a form and quantum and
time window that is close to optimal.
---------
No- you use what you have. There are optimisation methods which have been in
use for many many years but something with low fuel cost and high capital
cost will fall into the category of use it when you have it. If, at times,
you have excess capacity, then storage becomes of interest. If not, forget
storage. In the present time and for some considerable time to come, it may
be that such excess may not be available- depends on the system and its load
variations. There is no magic single solution.
Pumped storage comes into play if there is excess, relatively cheap,
capacity which can be used for pumping and storage for other times. If
there
is no excess of such generation over load demands- then no pumping is
done.
More to the point, you avoid having baseload cover, and spinning
reserve, and can tailor the transmission and delivery system to the
nameplate specifications of the plant. Since the *marginal* cost of
producing power from wind, wave and hydro is low, you can use it as
baseload or peaking. So you can replace baseload with it, which, as
currently configured, you can't. That in turn affects the economics of
an operation such as this, since, if you can promise and deliver a
certain quantum of power on demand, you cna negotiuate a longterm
price, and that means that you're more likely to get low cost loans,
state support etc.
-----
You do not avoid baseload cover or spinning reserve. Wind as baseload
requires it to be available all the time. Wind, tidal and solar energy
aren't. Wind as peaking may or may not be available when it is needed so
it
doesn't eliminate the need for spinning reserve. Similarly with solar and
wave power. | | | | | | | | | |
