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helot13
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# Posted: 31 Dec 2010 09:38pm
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Considering the premise that you were entirely off the grid, the power produced locally has to either be used or stored locally. Batteries are toxic, finite, and the technology is expensive. What are some alternatives to the current solution?
I thought of using the electricity to create hydrogen, then use the hydrogen as a fuel source.
I have also toyed with the idea of a flywheel, but the size and balance do not scale well.
The only other option I can think of would be converting the electricity to heat and using it to drive a Stirling engine which could be used as a generator.
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helot13
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# Posted: 31 Dec 2010 10:40pm
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I am reading a little bit about compressed air. Now this seems like a viable solution.
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fooboo
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# Posted: 31 Dec 2010 11:44pm
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Great question!
I think you get a different answer depending on what your input energy is (solar, wind, tide, geo, or hydro) and you'll get even more diverse answers depending on your latitude and other local factors.
In other words, what would be best for Northern Canada isn't going to be the same as Death Valley, California.
You also don't say if you have any tolerance to adverse effects of some of these storage systems in terms of noise and maintenance. Batteries are nice and quiet and fairly maintenance free. Steam requires daily interaction and is loud.
It also matters whether you have an excess of input energy or not. For instance, a fast moving waterfall gives you an abundance of "excess" energy that is just kinda lying around. Because of that, you don't need to be nearly as efficient in your capture as someone who's only input option is 5 hours of daylight in a northern climate and they must convert every tiny bit of input into something storable and the storage medium is susceptible to local environmental conditions (like extreme cold)
It also depends on what type of work you want the energy for. Household lighting? well pumps? Whole house heating? How many watts and amps are we talking about? This is typically where every alternative energy designer is going to start in their questions. What is the power requirement at the end of this exercise? From that answer you then work backward to size the pieces.
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MtnDon
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# Posted: 1 Jan 2011 12:20am
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If the premise is there is no grid connection at all and that electrical energy must be stored for future use, then it seems to me that currently the only cost effective thing to do is utilize storage batteries. Either the common flooded lead acid or AGM. Perhaps one day lithium-ion may be more cost effective. Perhaps one day the super capacitor idea will prove fruitful.
I certainly do not see the point of converting electricity to heat and using it to drive a Stirling engine which could be used as a generator. There are energy losses each time the energy is converted from one form to another.
I looked into compressed air using a motor/engine made by an Australian company. It required air compressed to very high pressures, like that used in SCUBA gear or even higher, in order to store enough air in a compact space. Those compressors require a large amount of power. I obtained some lab test results from them and it was really difficult to see an air storage system as being better than the good old lead acid cell. Maybe some day.
Contact URL. You'll have to request test results by email. I no longer have the data. Have a look at the air consumption rate per HP to drive a generator.
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MtnDon
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# Posted: 1 Jan 2011 12:26am
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IF there is a grid connection, on the other hand, you can use the grid as a 'storage' device. My power company buys excess power and pays more for it than we pay for the first 700 kWh per month that we buy from them. Only in the summer does our use exceed our generation. They actually write a check. That varies widely across the country, many power companies will only give credits to applied in future months. And all that is subject to change every year or so when the new agreements come around.
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SEOhio
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# Posted: 1 Jan 2011 09:34am
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This guy has a better budget and skill set than I do:
http://ludens.cl/paradise/turbine/turbine.html
SE Ohio
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maine_island
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# Posted: 1 Jan 2011 10:18am
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instead of looking at the problem as storing energy for later GENERAL PURPOSE use, think of performing some kind of SPECIFIC useful work now (when you have the energy) which "STAYS AROUND" and reduces the need for future energy use when you may not have access to available energy.
for example:
create ice - even if you don't need it at the moment, you will always need refrigeration in future, so create excess ice now when you have excess energy.
pump water uphill into storage tank - you will always need pressurized water in future, so create a big supply of it now.
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fasenuff
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# Posted: 1 Jan 2011 12:05pm
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MtnDon said it right, there is too much loss every time you convert from one type of power to another. Once you convert the electricity to another form of power and convert it back you lose a great deal of available power.
As was mentioned above you would need to do as much as possible when electricity productiion is at it's peak. Freezing ice would be one such thing. That way you would have cool drinks or be able to keep food longer. I do something like that now by running my small chest type freezer when I run my generator and freezing ice to keep food longer.
Pumping water uphill and storing it for later use is another. That stored water could be used for pressure at the faucet as well as running a small generator for limited power generation.
A wind powered generator could supply power at night at times but it would not be a constant or reliable source. But it would add some value to the total energy production.
In ancient Egypt they expeimented with batteries that were very different than the ones we use today. A look into those might provide some storage but they would not hold much or last long but may be more eco friendly. I am sure to equal even what is in a typical car battery would surely be large and bulky while needing constant care.
More than likely to do what you propose helot13 would require a combination of things to make it work. It could be done as long as you were able to make a large surplus of energy during the day so that the losses from converting from one form of power to another did not affect you as badly.
And then there is always the bicycle powered generator. With it you would atleast be in good shape. :)
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CabinBuilder
Admin
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# Posted: 5 Nov 2017 03:39pm
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Bumb by helot13..
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RiverCabin
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# Posted: 6 Nov 2017 05:14pm
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Quoting: maine_island pump water uphill into storage tank - you will always need pressurized water in future, so create a big supply of it now.
That worked great for Ameren UE up until the pump didn't shut off.
https://en.wikipedia.org/wiki/Taum_Sauk_Hydroelectric_Power_Station
This wasn't far from me and I saw the scour the day after it happened. Water can be dangerous stuff.
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slgerber
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# Posted: 8 Nov 2017 11:52am
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Has anyone done the calculations to see if a pumping station like Taum Sauk would be at all feasible on a small scale? For example, say you put a 5000 gallon tank at 100 foot elevation uphill from another tank with PV powered pumps/generators in between which fill the upper tank during the day and then generate power at night as the water flows down. How many watts could a system like this produce? Would it be anywhere near competitive with battery storage?
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Nicholas666
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# Posted: 29 Nov 2017 10:27am
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This is great question and a great thread! I'm glad that I've found it as there is a lot of useful information. Thanks for sharing your experience, guys!
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rayyy
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# Posted: 30 Nov 2017 09:37am
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Making hydrogen is an interesting concept. I tried playing with it once.It was a dismal failure though . It takes more energy to make hydrogen than the energy you get out of it.Storing it in bulk is a risky business too.Side effect are that it burns so fast that you can't control it.However,there has been some claims of being successfuly done.It would be wonderful if this were true.
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rachelsdad
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# Posted: 30 Nov 2017 03:39pm
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Making hydrogen is an interesting concept. I tried playing with it once.It was a dismal failure though
ME TOO, NOT FUN
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