"Physical Batteries?" Topic

It's ok if you want to laugh and point at this one.

Watching the news the other night, I saw a story about a gentleman who added solar panels and a wind mill to his house. Ok, the guy was a bit of a green peace goof and spent alot more on the equipment then he saves from the electric company. But something he said stuck in my head. He said his biggest problem with renewable energy were the batteries. Clearly he needs batteries, a lot of very big batteries, to regulate the power in his home so the lights stay on when the sun goes down. But the problems with chemical batteries are legion (toxic, expensive, life span)--especially in the eyes of green peace goofs.

But why not a physical battery? Just like fighter planes transfer energy from kinetic to potential, why can't the green peace guys use a physical battery to store the excess energy of the day. The best form I know of a physical battery is a fly wheel. I've heard of people experimenting with these for cars--for which there wholey impracticle (due to the inertia). Wouldn't a fly wheel system not be perfect fit for the green peace guy who's invested 10s of thousands of dollars in solar energy?

Is there a scientific reason why putting big fly wheels into the basements of houses around the country is not effective? Granted, they have an element of danger--but so does your water heater.

Just curious if there's a practicle physics reason why it's not done or is it purely economical?

Two remarks to this, one even vaguely wargames related:

The city of Arnhem experimented with fly wheels in trolley buses during the late 90s, but never got a satisfactory result. The old series of buses they tried this on have been sold – without fly wheels – to a Russian city.

The other point, I've seen simple applications of what was called an earth battery: simply coils of sturdy tubing dug deep into the ground, which stored the heat produced by water filled solar panels till it was needed at night. Not very high tech or expensive, but effective.

Oh, the wargames link?

Arnhem started using trolley buses in 1949, after it was found that the war damage to the street car lines was to extensive – and expensive – to repair. Just replacing the overhead cables was much simpler and cheaper. WWII era trolleys can still be sen in the Arnhem open air museum.

The city of Groningen took a similar decision: two of the tram lines could still be used, but downtown was in serious disarray after the point blank AT gun battle the Canadians and Germans had during the liberation of the city so trolleys took over there.

See, there was a link – and it was vague!

Sorry about the mess Gungnir. Tourists eh?

I'm no engineer but… a better solution might be to use some energy cracking water and storing the resultant hydrogen.

The simply burn the hydrogen at night.

I believe there's a island (probably Danish) somewhere in the Baltic does this – it's wind pwoered but uses hydrogen on still days.

Does require you to have a lot of water though.

Or possibly use some solar to heat water and use some kind of thermo-electric device? Solar heating of water even works here in Wales…

One solution is to use stone. Stone retains heat for along time,so gives it back slwly. Dig a great basin in the garden, fill it with stone, and circulate heated water. In the nigth and indeed through much of the winter it gives back heat.
In countries were electricity is cheaper at nigth, you use electrical heaters with a massive stone in it so that you can heat the stone at nigth and then blow air over the stone at day to give warmth.

Since most power plants use coal/nuclear/etc to heat water to make steam and use that to turn turbines, simply use your solar to heat water.

Look at it this way, hot water in a thermos contains about the same about of energy as a charged laptop battery. Once costs $5, one costs $75. USD

Regards, the Gorb

Heat is the easiest and cheapest way to store energy. But it is awful hard to convert to electricity to run your lights and laptop. Especially the low quality (temperature) heat most easily stored.

The problem with a flywheel, even in this one-off application, is the loss of power though friction in the bearings.

I also think the economies of scale in mass production aree limited due to the sheer mass of the flywheel required.

One advantage of a flywheel over low quality heat is that the energy in flywheels is relatively easy to convert to electricity.

Do what they do with Hydroelectric Dams – use the excess power to pump water back UP.

So, a water tower.

Pat

The French are working on compressed air for power storage (including a car). From some of my work for oil and gas storage I know that compressed air motors can be small and be a very efficient way of powering a lot of equipment without the need to convert back to electricity.

Quite a few houses locally (Scotland) heat water from solar power for heating in the winter and wash water in the summer. They claim that it pays.

x42

I know of several caravan sites in North Wales that use solar heating for their shower units. One owner claims it saves him 80% of his fuel bills.

So at least for round here, solar heating is a better bet than solar electricity.

You have pretty much boiled down the whole energy issue down to its most basic problem. How do you store energy? All batteries don't store energy, they make electricity chemically. You can "recharge" a chemical battery after it's been discharged by running current through it, but it doesn't store the electricity. The electricity running into the battery causes a chemical change that when the current is shut off, causes the battery to discharge electricity (until the chemical reaction exhausts and you have to run current into the battery again). The chemicals in the battery will eventually exhaust, meaning you have to buy new batteries.
All other methods of "storing" electricity are actually different methods of just creating electricity. Flywheels, fuel cells, warming bricks, they just a method of taking the energy you have now, to create a condition that you can then use to create more electricity later.
The problem is that all these methods are inefficient. Chemicals degrade, flywheels have friction, and heat exchangers (Heating bricks) are really inefficient, and pumping water up in altitude doesn't generate as much power as you used to pump it up. Now as far as it goes, the water pump method is a rather more efficient method then the others, because damns can use extra power during off peak times to do this, but the conditions that you need to do this is not very common. Also all good location to build damns pretty much already has damns built there, so a lot of new damns are not on the horizon.
If you could come up with a true method of storing energy (electricity or something else) you will end up being richer then Bill Gates, and more powerful than any other person on the planet. You will have every country on the globe beating a path to your door to get your method, and you revolutionize our society, I am not joking about how powerful a step forward this would be. It would solve the world's energy problems for the next couple centuries without the need to find new energy sources.
Unfortunately our current theories of physics say that finding something like this would be very improbable.

Yeah, the problem is that currently batteries have the greatest efficiencies, and they aren't that good.

Of course, you could say the same about any part of the energy chain – increase the efficiency a bunch, and it yields great energy "bonuses".
-Kle.

More wargaming related trivia: Some of the old Car Wars source material speculated that big, heavy, perfectly balanced, near-frictionless flywheels could be used to store energy in an electric car, allowing blistering acceleration equivalent to a gas-powered muscle car.

Assuming the flywheel doesn't break loose and steamroll everything in its path.

I also remember reading years ago that if the miniaturization of batteries had advanced as rapidly as the miniaturization of computers and microchips, a battery the size of your thumbnail could power an aircraft carrier.

Interesting discussion.

"The problem is that all these methods are inefficient."

For this particular application, inefficiency isn't a killer. The unused energy from soloar or wind sources is wasted. Coal, oil, or nuclear power plants produce based on demand. Storage from these plants isn't a big issue--don't burn the chunk of coal if no one wants it. But solar and wind do not. Any storage, regardless of efficiency, is better then no storage at all. But obviously, better efficiency gives a bigger bang for the buck.

So there's no thearetical reason why the guy could not implement a fly wheel in conjuction with his wind mill and solar panels. But now here's where the rubber meets the road. How big of a fly wheel does an one need in order to smooth out the energy for an average home?

It strikes me that the best approach is to use the larger grid – sell power into the grid when you are producing surplus, buy it when you are not and others are.

Of course, you are stuck with the "ungreen" parts of the grid and you are not self sufficient; but if you want practicallity instead of smugness it is fairly sensible.

Which is how it's done here. Alas the red tape required makes it a formidable exercise.

But it must be cool seeing your electricity meter run backwards, which is what happens when you're producing a surplus.

A big spring? Or a rubber band?

Sun shines, motor winds your giant bungee. Sun goes down, bungee spins motor the other way, electricity!

Gear it right and you could build it at home.

Andrew

All sorts of things can be done at home. Someone I know on Anglesey heats an iutdoor swimming pool by passing the water through several hundred metres of black-painte dhosepipe coiled up on a tin roof.

Saves him a fortune – even in Wales.

An outoddor swimming pool in wales? What sort of masochist does that?

Pat

Friction is, indeed the main loss of efficiency in a flywheel. And, regardless of whether the source of power is "free" the aparatus for storing it is not. A flywheel capable of storing that much energy is prohibitively expensive.

A fuel cell is pretty good at generating energy – but it takes a lot of power to crack hydrogen out of water. If you can overcome the expense of the fuel cell and use wind/solar power to break the water down, you should be able to smooth out the flow. I'm not sure the technology is there yet.

About that selling energy back to the power company bit – you buy energy from them at the retail rate. They buy it from you at the wholesale rate – about 1/5 of what you pay them. With power inverters (necessary to convert the power from a solar panel to something your house can use) running at several thousand dollars, you have to be committed to the house for the long term – at least 10 years – before you break even.

The next generation of hybrid cars are supposed to be plug-in which means that they can not only juice up from the house at night, but they can power your house for 2-3 days in the event of a disaster.

Wyatt

"but they can power your house for 2-3 days in the event of a disaster."

Now that's interesting. I like to have back-up systems at hand – I have a propane fireplace in case of winter power outages as well.

A near frictionless flywheel is indeed possible. They used to sell them as gimmick toys in places like The Discovery Store.

It consists of a wood half-pipe section with magnets embedded about a fourth of the way down from either end of the pipe. The flywheel consisted of a short pole with two circular magnets on it, the same distance apart as the magnets in the half-pipe. One end of the flywheel pole tapered to a rounded point. This was placed against a vertical strip of glass (usually mirrored, though that has no effect on the flywheel's operation). The flywheel then floated, suspended above the half-pipe by magnetic repulsion. The "fun" of the toy was to try and spin the pole so that it would begin to spin on its own, nearly endlessly, without accidentally knocking it off the half-pipe. The only point of friction (aside from air) for the whole apparatus was the point where the pole tip touched the glass.

Okay, that's a toy. But it demonstrates that the following apparatus might work: Imagine a framework basically shaped like a tire; a big U extruded into a torus. The innerside of the "tire" is ringed by magnets, all with the same pole (N) pointed towards the center of the doughnut. The two sidewalls also have magnets with N poles pointed inward.

Now, insert a flywheel whose thickness is less than the inner dimensions of the U, but whose diameter is greater than the torus's central hole. The flywheel consists of magnets with the N poles pointed outwards. Note that in this configuration, the flywheel is suspended in the center of the U torus, yet magnetic repulsion prevents it from moving sideways out of the torus. Now, spin this wheel. Voila, circular movement with essentially no friction. (Note that the flywheel could be located on an axle and be larger than the torus assembly; the magnetic torus could simply be a "frictionless bearing.")

So the question becomes, can this apparatus be used to produce work?
Say, extend an axle from the middle of the flywheel and create a generator along it?

The tricky part is keeping the flywheel's force from overcoming the magnetic force (which is fairly weak) and smacking inadvertently into the torus framework. Also, how much with the shear effort of spinning the generator reduce the efficiency of the flywheel? Would the magnetic forces in the generator be too much for the magnets in the flywheel assembly?

Engineers? Physicists? I probably have something wrong in the above, so feel free to offer any corrections!

Hi

We always bump into the three laws of thermo dynamics.

but in one sense we are looking at it backwards. Most power generation is turning heat into power. Burn coal, heat transfer; nukes heat water, even the internal combustion engine is, in essence a heat pump.

In effect, the electricity cannot tell what created it. Using the daylight to heat water that is then stored and moved when cool to produce power is a common solution that is being used now.

I usually complain about how the greens have successfully convinced you of things that aren't quite true, but this is a case where the guys against alt energy guys have clouded the issue.

right now, there is a project to cover several square miles of nevada with reflective material to store energy as heated water. The only problem in this alt-energy project is the placement of these mirrors and hot water storage might disrupt the life style of some desert tortuse or something. We have a lot of desert where i am. this could be a good solution except for the one objection.

Rocky

My immediate thoughts are…

a) It's a rare tortoise so presumably has a restricted distribution. Why not move the construction?

or

b) If the tortoises have a wide distribution and are still rare, there's plenty of unused habitat out there. Why not move the tortoises?

Reptiles (at least British ones) seem to cope with being mvoed about quite well.

Bangorstu, check the latest SJG Illuminated Site of The Week; Some research team have come up with a practical method of 'artificial photosynthesis' which utilises the solar power for water-cracking and then uses the split gases for fuel cells. A near constant power source day or night.

b) If the tortoises have a wide distribution and are still rare, there's plenty of unused habitat out there. Why not move the tortoises?

Reptiles (at least British ones) seem to cope with being mvoed about quite well

A local wildlife resource officer told my son's cub scout group that they shouldn't pick up tortoises and move them, as the tortoises become confused by such actions and lose their bearings. But that's a different issue.

Back on topic: There's a device called a Sterling Engine which operates by changing air pressure around a piston. A company is developing a parabolic mirror system, slightly smaller than the big consumer satellite dishes from the '80s, which uses sunlight to heat the piston chamber and run the engine. The engine runs a generator, storing electricity for later use. Very neat idea, pollution free, and doesn't require nasty chemicals to build or maintain. Only drawbacks are minor noise concerns and the necessity of sunny days. (So Seattle's out of luck. )

Maybe he could make a giant array of Leyden jars out of recycled glass containers.

Theres always the Frankenstein approach – use surplus energy to re-animate dead hamsters, which will then run on treadmills during the slack times.

Just because he doesn't want to contribute to global warming doesn't make him goofy.

There is a method that can be used to warm houses in temperate climates, which is pipes buried underground. In the winter enough heat is retained by the ground to heat your house- forgive me, I can't remember the name of the prcess to google, and heard about it on the radio a couple of years ago, so am a bit hazy. I do remember the only power cost you have is a small electric pump.

It is expensive to retrofit (for starters your garden looks like the Somme in 1916 while they bury the pipes), but there is no reason all new building shouldn't have it.

Hi

On these planet saving solutions, the advocates NEVER tell you about the carbon footprint of MAKING these "green" technologies, or when the "Break Even" point is reached.

Personally, I spend about 30 bucks a month on electricity. Thus, a system that costs $3,000 USD would need 100 months, assuming NO OTHER COSTS, just to break even. In that the Canadian experiement in retrofitting governement WW2 housing to their new standards cost some stupid number like a half a million to effect, the building won't survive long enough to show a savings.

Not cost effective.

But it makes you FEEL good.

Rocky