Put yourself in the mindset of setting up a large home or a small business that runs off the grid. Most people would use solar panels and store energy in lead acid batteries. Now, let's say batteries only last 15yrs max and you won't ever be able to get lead acid batteries again and parts to repair whatever system you chose will be extremely hard to come by; you want your system to be be as simple, bulletproof ,& reliable as possible. What's the next best way to store energy to use through the night or on a stormy day?

I considered a water tower; a pump fills the tower during the day, and during the night, the water flows out through a turbine generator to produce electricity. Personally I don't think it would work well. I think there's not enough energy stored in elevated water to accomplish the task, or if there were, the flow rate required would empty the tower in minutes flat. That's not based on any math or science, just a hunch.

I considered hydrogen production via electrolysis during the day, hydrogen powering a generator at night. This seems feasible to me, but would put a lot of hours on the generator, and when the generator wears out, it's lights out for a long time.

i considered compressed air; compressor fills a tank during the day, air motor runs a generator at night; again, same problems as both the water tower (i suspect) plus the hydrogen/generator.

any ideas?

 

What about geothermal power? But that depends on where you live & how deep the hot-rocks are I suppose.

 

Biogas! Raise pigs and use the pig manure to make methane. Pigs will eat anything and are very efficient.

http://www.abc.net.au/news/2007-10-11/pig-manure-sweet-money-for-thai-farmer/696070

 

If you want to have an industrial process to store energy, you will need the means to fabricate parts. Thing about civilization, it is what supports our life style is going to be hard to replace if it is gone, and everything wears out.

I like the pigs and methane idea, but you will still need a way to store the gas.

 

What about geothermal power? But that depends on where you live & how deep the hot-rocks are I suppose.

it actually doesnt, even down 100m the energy that can be gained from there will save you enough energy to make a viable installation..
theres an installation in southampton, England. the salt water is drawn to the surface at 70deg C, and while this isnt enough for steam etc, it is then raised to 100degC, through a generator(it cools the engine) but the energy to raise the water that last 30degrees is saving a lot of energy as opposed to raising it 100degrees..
it also provides all the air con, hot water and electricity for the reclaimed docks at southampton.. so noone can argue with its effectiveness really!
Here's a link

 

How about a gigantic bank of super caps?

Or a super-conducting coil?

 

even down 100m the energy that can be gained from there will save you enough energy to make a viable installation..
theres an installation in southampton, England.

Interesting, but I see no evidence from the link you gave that the installation is viable.

I find it very suspicious that the one fact I really want to know seems totally absent.

How much does it cost to make all those savings in money, infrastructure and carbon emissions?

If the total savings are, say, £100 million over ten years, and the power station costs £20 million a year more to run than a conventional station, then that means that the scheme is subsidised to the tune of £10 million a year.

These figures are made up from thin air, just for illustration, but why is the actual cost hidden?

This is not to say that this is a bad scheme, but I sense a little bias.

Maybe the unbiased truth is out there somewhere, and maybe the scheme actually pays for itself. Hard to know, and so hard to judge the real effectiveness, when most of what I see is hype.

Sorry for going a little off-topic, but I found this link interesting, as I live close to Southampton.

Back on topic - I agree that superconductors look like an exciting way to store big quantities of energy in the future. It is being done now, but probably not viable right now.

 

Interesting, but I see no evidence from the link you gave that the installation is viable.

I find it very suspicious that the one fact I really want to know seems totally absent.

How much does it cost to make all those savings in money, infrastructure and carbon emissions?

If the total savings are, say, £100 million over ten years, and the power station costs £20 million a year more to run than a conventional station, then that means that the scheme is subsidised to the tune of £10 million a year.

These figures are made up from thin air, just for illustration, but why is the actual cost hidden?

This is not to say that this is a bad scheme, but I sense a little bias.

Maybe the unbiased truth is out there somewhere, and maybe the scheme actually pays for itself. Hard to know, and so hard to judge the real effectiveness, when most of what I see is hype.

Sorry for going a little off-topic, but I found this link interesting, as I live close to Southampton.

Back on topic - I agree that superconductors look like an exciting way to store big quantities of energy in the future. It is being done now, but probably not viable right now.

na its not, its genuinely viable, its just for the council, and they need muggins data.. iv got an a1 poster here of everything it does.. see if i can take a highres image and upload.. i know the mods wont like it but its interesting stuff.
i do get what youre saying, but my point stands that even from a small depth, a heat increase can be obtained, and therefore an energy reduction =]
it has to be said that if an installation is too shallow, then there could be energy sinking in the summer, and energy sourcing in winter, thus heating and cooling the home if it was fitted in a domestic situation =]

superconductors are probably never going to be viable, unless a superconductor can be produced to work at room temperature.. and super caps, a nice idea, though unpredictable charge storage if a heavy load is placed on them?

 

based on your topics heading.

Lead acid batteries ARE a very efficient, SIMPLE way to store large amounts of energy. The parts and processes are so easy to understand and implement that these devices were being made in France by various famous scientists with access to nothing more technological than a blacksmith, sulfuric acid, wood, pitch(tar) and lead and copper.

Boiling water for steam with the use of concentrated sunlight from a metal parabolic dish was also done in the era of 1810-1820 again in France when a man built a printing press for exiibition at a Fair of some sort. I've not read those books in ages so my data may be off slightly. I want to say the date of the printing press powered by solar energy may have even been earlier, around 1800.

When our advanced industrial society goes the way of the Dinosaur, the simple techs will be all we have. Let's hope humans still have trees and fire in such a future.

 

Liquid metal batteries are still in development, but fascinating.

http://www.ted.com/talks/donald_sadoway_the_missing_link_to_renewable_energy.html

 

Water tower: (assuming its not used to catch rain water.)
You could ... increase the virtual height of the tower by putting a heavy weight on top of the water. (ergo: hydraulic pomp lifting some heavy weight(s).)

Fast growing tree's ? ;-)

 

Heat storage. It's low cost and highly efficient. They are doing it in Spain in the solar power tower facilities, with some success.

 

Heat storage. It's low cost and highly efficient. They are doing it in Spain in the solar power tower facilities, with some success.

That's interesting. What's the best way to turn heat into electricity? The first thing that comes to mind is a stirling engine, but I have yet to see a stirling engine capable of producing household power that's not snake oil.

 

Actually I've heard good things about Stirling Engines, it is mostly a matter of scale. During the gas crunch of the 1970's they experimented with them for cars. They worked, but the lack of throttle control killed the concept. I've always wondered why they couldn't be used in hybrids, where driving a generator and constant speed are not incompatible.

Anything that can drive a car has power.

When you really look into them they are not that dissimilar to a ICE engine, but the differences are really interesting. The fluid that does the thermal transfer needs to be as low viscosity as possible. Hydrogen or Helium are considered good mediums, they both flow much freer than air, which directly affects conversion efficiencies. The piston arrangement can be very similar, but some mechanism for thermal transfer has to be added.

Like a air conditioner they are sealed though. Run a Stirling Engine in reverse and it becomes a heat pump, it transfers heat from one side to the other. They are used to cool helium to 2 or 3° Kelvin in sputtering machines. Servicing these machines was one of my jobs in my machine maintenance days.

Basically they are transducers, motion to heat pump, heat to motion.

When it was invented, so I have read, there were no materials cabable of handling the heat. A steam engine uses the water to keep metal cool, but there is no such mechanism for a Stirling engine. That is not the case any more.

 

That may be true Bill, but have look at what google has to offer. The only thing I find when I google stirling engine is explanations of theory, and some desktop toy models. I remember reading a while back about a big investment to develop parabolic mirrors with sitrling engines at the focal point, and then a little while later I believe I read that the company was being persued for fraud.

For a tried & true technology as this supposedly is, I would think that I should be able to find one of practical size for purchase. I conclude that nobody is buying them because nobody is making them, and nobody is making them because _______ (I assume because they suck and nobody would buy them).

I have seen video demonstrations of stiriling engines on youtube, but never with a load. That's my red flag; you see it all the time with overunity people - they show some grand "generator" spinning, but no load attached to it.

There's a picture of a 55KW stirling engine on the wiki page, but I can't find any info on it.

 

That's interesting. What's the best way to turn heat into electricity?
...

Well that is really the "holy grail" of renewable energy; how to turn low grade heat into electricity cheaply and efficiently. Consider photovoltaic power turns maybe 15% to 20% of sunlight into electrical power, with close to 80% sunlight lost as heat. You can put some black painted metal in the sun and easily harness 50% of the solar energy as heat and cook eggs on it at 70'C, but how to make that heat generate electricity?

I've spent a lot of years thinking about it myself but have only really come up with designs that are cheap but very low efficiency or good efficiency but have a real high cost of installation (ie stirling engines).

Re the Spanish solar tower installations they use liquid salt to store the heat energy, then they use the same steam turbines etc to generate electricity through the night from heat that was stored in the daytime. So they already had plant to turn heat to elec.

http://en.wikipedia.org/wiki/PS10_solar_power_plant

...
The first thing that comes to mind is a stirling engine, but I have yet to see a stirling engine capable of producing household power that's not snake oil.

There's plenty of nice stirling engines out there, I've seen a few larger ones on the net over the years.

(complete with wood furnace)

Try google images for lots of large stirlings;
http://www.google.com.au/images?q=large+stirling+engine

 

Put yourself in the mindset of setting up a large home or a small business that runs off the grid.

off the grid, and/or sustainable?

For a residential scenario, passive heat sinks and storage battery will likely be the most efficient. You could burn wood, but is it sustainable?

One must consider the available energy and the consumed energy and justify the difference. The method of capturing excessive energy when it's available to resuse later depends on the energry source.

The available/use formula will likely dictate that you sleep, or hibernate the activities during those periods that have low energy capture.

Going off grid doesn't make a lot of sense if the capital expenditures exceed the cost of energy usage from the utility. The utility will often be far more efficient in operation than home brew. Aquiring a property with a stream running through it, one that could be altered, may be a better capital investment than a sterling engine.

 

Just thinking out loud. (every thing has its limits/optimal_usefulness.)



Heat storage:
- Needs to be held in a container that prevents heat dissipation.
- The higher the temperature the higher the frequency of the radiated heat.
- Every material has its own optimal behavior within its own boundaries.

Combined these suggest a heat storage container will have its own temperature boundaries in which its still considered to be working optimal. And to store more energy you need to expand it in size. (bigger single unit or more same size units.)

For energy centrals that need to build up a surplus in the day, so that they can also provide electrical power at night, this is not really a problem I think. (so heat, in this case, works ok as solution.)

But as a more general long term energy storage is seems less optimal. (different targets, or energy levels, require different systems/solutions.)



Some others that come to mind:
- Gravity: Minimal energy lose(?), but assuming kinda limited in range for the amount of matter/mass that needs to be used. Not transportable as system.

- Oil (the bacterial(wip) generate kind): Already proved it self (Oil itself). Including the potential down sides. Easy storage and transportability (whiteout the need for some energy conversion).

- Electricity: Most versatile in its use, but it also seems to be the hardest one to store (as such). Unless you have a superconductive system that needs no energy to maintain it. Would be DC (always?), not sure if that's a problem.

- Hydrogen: Although this is still in its wip stage (compared to Oil. Both in its usefulness, efficiency (all aspects), and its downsides.)

- Fusion: Interesting, but major wip ... although where never going to beat the Sun at its own game. (well, not anytime soon that is.)


Excuse the (use).

 

I considered a water tower; a pump fills the tower during the day, and during the night, the water flows out through a turbine generator to produce electricity. Personally I don't think it would work well. I think there's not enough energy stored in elevated water to accomplish the task, or if there were, the flow rate required would empty the tower in minutes flat. That's not based on any math or science, just a hunch.

I am surprised. The largest energy storage facilities in the U.S. are pumped water storage. The Ludington Pumped Storage facility is over 1800 MW peak power and ~ 15,000 MW-hrs stored energy. I think the round trip efficiency is ~ 70%. See http://www.consumersenergy.com/content.aspx?id=1830

 

I am surprised. The largest energy storage facilities in the U.S. are pumped water storage. The Ludington Pumped Storage facility is over 1800 MW peak power and ~ 15,000 MW-hrs stored energy. I think the round trip efficiency is ~ 70%. See http://www.consumersenergy.com/content.aspx?id=1830

Hey, that's encouraging. I hope there's not any catch, like "the efficiency doesn't scale." Maybe it's one of those things you just have to try it and see...