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238 comments on DrumBeat: August 12, 2006

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DIYer on August 12, 2006 - 8:52am Permalink | Subthread | Parent | Comments top
Imagine, if you will, approx. 100 billion marble-sized 'steelies' rolling out of a dam sluicegate atop a sloping mountaintop plateau
... The steelies would grind up your turbine blades, regardless of what you make them from.

But an oversize elevator, with motor-generators, lifting something like a kilometer cube of earth? Or gather up all the used lithium batteries from the cellphone industry and tie them in parallel?

Flywheels?
Supercapacitors?
i got it __ a giant wimshurst machine
... fill the lake with mercury

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totoneila on August 12, 2006 - 9:47am Permalink | Subthread | Parent | Comments top
Hello DIYer,

I am imagining more of a multiple series of small ribbed metal logs across the sluicepath and connected to gearboxes to spin the correct RPM for the dynamos, not a turbine.

Because water is less dense than steelies: that is why you need the big drop to spin the turbine.  The steelies could roll much slower because of their tremendous energy density.  The arch design of the sluicepath would determine the rolling speed and how many millions of tons of rolling pressure would push the steelies relentlessly forward.

Bob Shaw in Phx,Az Are Humans Smarter than Yeast?

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DIYer on August 12, 2006 - 10:11am Permalink | Subthread | Parent | Comments top
I understand your fascination with steelies, they're fun to play with. But along with the other objections listed below, I doubt you could get more efficiency out of them than falling water. You're still allowing something to fall and trying to recover energy from it. (note: filling that lake with mercury would allow you to use a magnetohydrodynamic generator with no moving parts other than the mercury stream)

But as others have mentioned, there is a tremendous amount of embedded energy in the steel itself. We use water for this application because (maybe not in the Sonoran desert, but some places) it is readily available, environmentally innocuous (give or take a breaking dam) and nature does some of the lifting for us.

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wkwillis on August 12, 2006 - 6:08pm Permalink | Subthread | Parent | Comments top
NaK is cheaper than mercury, a much, much better conductor, and fluid at any place they need electricity for summer airconditioning peaking.
Go with flow cells for cheap energy storage for any place that doesn't have hydroelectricity to use instead.
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memmel on August 12, 2006 - 10:13am Permalink | Subthread | Parent | Comments top

Grandfather clock anyone ?

I've done a lot of reasearch here and at the end of the day the best storage for cost and energy density is a liquified gas. Liquid nitrogen is and obvious choice. C02 is another ammonia and organics are possible.

Now these sources have been dismissed for mobile power sources because of there energy density but they all work well as a capacitor for an eletric network. The beauty of liquid nitrogen is its free.

See

http://en.wikipedia.org/wiki/Liquid_nitrogen_economy

http://www.stirling.nl/sp/sp3.html

I'm working on and alternative method to generate that
has no moving parts based on vortex tubes
http://www.iprocessmart.com/Exair/vortex_and_cooling_intro.htm

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JoulesBurn on August 12, 2006 - 10:37am Permalink | Subthread | Parent | Comments top
I would disagree with the statement that they all work as well as a capacitor in an electrical network.

One problem is the heat transfer--where and how to dump all that heat when you liquify it and then getting it back later. That impacts the efficiency of the complete cycle as well as the rate at which you can get the energy back out. That is an issue with LNG.

Converting high quality energy (electicity) into heat (latent heat potential, in this case), has inherent disadvantages.

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Substrate on August 12, 2006 - 12:48pm Permalink | Subthread | Parent | Comments top
It might be possible to store the lost heat in water and add it back later and even add more heat to it with cheap and simple thermal solar panels which would add (simple) solar energy to system.
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memmel on August 12, 2006 - 9:35pm Permalink | Subthread | Parent | Comments top

Yes its a thermo cycle so there is the inherent loss but your losing energy that would be wasted to add peak power handling capability. Pumped storage has losses also. As long as the losses are resonable and I consider 50% reasonable then it makes sense to add the capacity. Consider the effect of having a several hundred  thousand gallons of liquid nitrogen stored at a wind farm it makes them viable for full load. In the home in the summer the liquid nitrogen can be used directly for air conditioning and also electric generation. Massively reducing the load. Also if you have a home windmill and solar panel your liquid nitrogen storage system means you keep the energy you generate or if you do sell back to the grid you can sell at peak price rates so your in control of when and how much energy you put back on the grid.

In the case of a wind farm or solar array located in the desert when you boil the liquid nitrogen you will be able to condense a fair amount of water from the atmosphere so it also makes it a source of water and of course nice cold air in the desert.

The energy density of liquid nitrogen is pretty high not quite enough to make it a good system for mobile transportation but its really quite reasonable for fixed energy storage.

Finally a co-product would be pure C02 this can be combined with electrolysis of H20 to give you H2 which gives you CH4 and you have a product for organics production.

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DIYer on August 12, 2006 - 11:53am Permalink | Subthread | Parent | Comments top
The beauty of liquid nitrogen is its free.

The last I heard it costs about the same per gallon as milk. In fact the author of the piece was amazed at how closely it tracked milk over the decades.

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memmel on August 12, 2006 - 3:43pm Permalink | Subthread | Parent | Comments top

I meant the working fluid i.e nitrogen.

The big disadvantage right now is the cost of creating it.
The use of stirling engines help and as I said I'm investigating using hirsch vortex tubes. There are also acoustic refrigeration. Needless to say efficient condensation of gasses is not and area that has recieved a huge amount of research since regular compressors work well even though there not efficient. You can use other working fluids the only real requirment is the boiling point is lower then room temperature. The energy is from the phase change liquid->gas.

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DIYer on August 12, 2006 - 4:25pm Permalink | Subthread | Parent | Comments top
Hmm. I looked at your site. You'll still run into some laws of thermodynamics. Extracting useful work from a temperature difference is always going to be less than 100% efficient.

And the cost of LN2 is almost entirely the cost of the energy to produce it.

If I had the money, time, and patience to build an energy storage system in my garage, I'd go with nickel-iron batteries. Your energy out / energy in is only about 40% but they last forever, have no moving parts, and are beautifully low-tech.

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memmel on August 12, 2006 - 9:22pm Permalink | Subthread | Parent | Comments top
I thought a lot about batteries but they don't seem to provide the load response that a thermodynamic system can. LNG is also potentially a good choice but again with liquid nitrogen you don't care about the working fluid. Both work well for the major peak load problem air conditioning since the effectively replace that use case via cooling the air using a stored refrigerant. Current refrigerants are also a good possibility I'd say freon but it not freon any more. The problem with anything not liquid nitrogen is you have to store the gas till you compress again which is why I chose liquid nitrogen since you can exhaust to the atmosphere.
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odograph on August 12, 2006 - 2:50pm Permalink | Subthread | Parent | Comments top
New flywheel product announcement:

http://www.treehugger.com/files/2006/08/load_balancing.php

looks interesting.

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TrueKaiser on August 12, 2006 - 8:46pm Permalink | Subthread | Parent | Comments top
it's a ad, ignore it.
key words here
Should the prototypes be proven
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