Storing wind energy as heat?

I'm sure there are folks here who have hot water radiant heat systems in their cement floors......either in homes, shops or other. I suspect there are a few folks with wind generators.

Is there anyone who is using a wind generator to heat water that is then pumped into their hot water radiant heat system to store the wind energy as heat? It seems to me a slab floor makes for a pretty big battery. :idea:

Wind today has been blowing a constant 20 mph with gusts to over 35 mph. Would love to see it being put to good use vs. just rattling the windows and causing drafts.

Those systems are designed to radiate, so they will probably not store the heat for very long, or very effectively.

Maybe a geothermal system, or other underground storage system designed for the purpose would work better?

(quoted from post at 15:15:28 02/12/19) I'm sure there are folks here who have hot water radiant heat systems in their cement floors......either in homes, shops or other. I suspect there are a few folks with wind generators.

Is there anyone who is using a wind generator to heat water that is then pumped into their hot water radiant heat system to store the wind energy as heat? It seems to me a slab floor makes for a pretty big battery. :idea:

Wind today has been blowing a constant 20 mph with gusts to over 35 mph. Would love to see it being put to good use vs. just rattling the windows and causing drafts.

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There is no doubt at all that if you get the floor mass hotter it will take longer for it to need to have heat added by your boiler, or whatever heat source you use, so yes you are storing heat. If you get it too hot however you will lose the energy when you open the windows.

We had plans to put a bank of heater elements in our gasified
boiler storage tank. Figured it could dump excess wind or
solar if we finally got setup.

Specific heat is the ability to store thermal energy. THe specific heat of hydrogen is around 14. the specific heat of granite
is less than 1. The specific heat of water is 4.2 (has lots of hydrogen) So concrete isn't as good as a tank of water by a wide
margin. Jim

Jan, I'm no chemist but to say water has "lots of hydrogen" is somewhat misleading in this case I think. So does sugar and so does any other compound containing hydrogen. But you are comparing free hydrogen (hydrogen gas or H2 I suspect) to hydrogen tied up in a chemical molecule. No sure how this ties in with your statement, I'm just mentioning it as a point of interest.

Interesting idea. Let's do the math. If you use 1,000ft2 of basement with a 6 inch thick slab.

1000 x .5 = 500 cubic feet of concrete
500 x 140 = 70,000 pounds of concrete

If you raise the temperature of the concrete 10 degree F: 70,000lbs x .2 btu/lb F x 10 deg F = 140,000 BTUs of energy stored.
140,000 BTUs of energy is 41 KWH.
If you pay 10 cents per KWH you can store about $4 of energy.

If you raise the concrete temperature 20 degrees F you double the storage capacity. At some point your house it too hot but you could control this somewhat by insulating the floor with rugs and pulling them up to release heat.

What actually makes more sense is to install an insulated water tank in your basement. You could raise the water tank temperature 100 deg F. Water also has 5 times more heat holding capacity per pound than concrete. A 500 gallon tank of water can store 417,000 BTUs of energy if heated 100 deg F. You would have to heat the concrete slab 30 deg F to match this.

It takes 14 (or more times as much heat input to heat the same mass of hydrogen as it does granite. Water has lots of hydrogen and therefore is a better place to store heat than granite (concrete like stuff) (it is nt easy to store hydrogen gas, or compress it to a liquid to store it (nasty cold) so I choose water. Jim

If you want to consider the thermal approach, in addition to Specific Heat other variables include how long you expect to store the heat, and how you expect to recover it and for what. If you store it in water, or anything else for that matter, you will have to insulate it well if you expect to keep it for any length of time.

You can store more energy in a phase change, e.g. water to ice and back. Before refrigerators remember they stored ice in sawdust for a good length of time. While I have not looked it up, I suspect the phase change is what made this work. A lot of buildings freeze water during off peak hours and thaw the ice to cool during peak hours.

I strongly suggest you do the math so you don't spend a lot of money on something that will not meet expectations.

Good Luck.

Paul

Hello Janicholson,


Specific heat is the amount of energy that it takes to raise the temperature of a substance 1 degree Celsius. That is the way I remember it. Some one else may chime in?

Guido.

Modirt;
they are installing wind turbines in my neighborhood and i'm a member of our association. After sitting thru many meetings; i've learned alot. The first
fact you brought up about the wind speed on the ground is a common misnomer. Wind speed is measured, in our area, at 100ft off the ground. That's why you
don't see wind turbines on the ground, some places use 75ft but i think that's about as short as it goes. our area isn't any windier then other places on
the ground but has a very sought after constant wind speed at 100ft.

Hello Janicholson,

Never Mind......?.I remembered the rest of the story. Each substance also has an assigned heat value jesh!

Guido.

Some geothermal HVAC systems pull heat from the ground to heat a building in winter and reverse in the summer to push heat from the building back into the ground to cool the building.

getting enough amps to heat water is the big problem storing DC in batteries then have enough AC amps from those DC batts to heat water. Just get a LP water heater you will be many$$$$ ahead.Just figure how many DC batts and where to store them then cost to convert the DC to AC AND HAVE ENOUGH AMPS TO DO THE JOB. Just how much hot water do you need for what another problem to figure out.Go price the batts then the cost making AC from them. LP IS THE EASY AND CHEAPEST WAY TO GO.

There's a plant in the middle east somewhere that uses solar heat to melt salt and
stores the energy that way. Then the molten salt runs steam turbines to generate power
when there's no sunlight.

LOL this is what's so funny about all this. I looked into a wind generator. Cost and everything even with government subsidies at the time in tax breaks would take about 20-25 years to break even. Life expectancy of the units I looked at? 25 years. Now that was just tied into the lines with no other changes than making my own electricity. Selling the extra to the power company. No battery storage system or anything else. Run off of my power when I could and theirs when I can't kinda thing. A decent generator isn't cheap by any means. The companies selling em sure made it sound good. But that's why you don't see more personal setups.

Like this storing heat idea. May sound good up front. And it may well work. But like with my basement. How much is it going to cost to break out the old concrete (I'm too tall to raise the floor) buy the materials and install the system and then re-pour the floor? Then what's the wind genny gonna cost. At 63 will I ever break even or am I just spending money to make an environmental statement? Kinda like here. When it's 30 or colder electric cars don't work well at all. So it's a 6 months a year car here. So about the only folks here with one have it to make a point and it sits unused for 6 months. Awful expensive statement.

Just questions I have.

Rick

Have you read any of the studies that say that taking energy from the wind makes it weaker, and here in the Continental USA, because of the wind farms, the Jet stream is sinking out of Canada more and more and bringing the colder polar air with it?

(quoted from post at 04:15:30 02/13/19) Have you read any of the studies that say that taking energy from the wind makes it weaker, and here in the Continental USA, because of the wind farms, the Jet stream is sinking out of Canada more and more and bringing the colder polar air with it?

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bwillet, be careful there of calling coffee shop gossip "studies", LOL.

(quoted from post at 22:09:56 02/12/19) LOL this is what's so funny about all this. I looked into a wind generator. Cost and everything even with government subsidies at the time in tax breaks would take about 20-25 years to break even. Life expectancy of the units I looked at? 25 years. Now that was just tied into the lines with no other changes than making my own electricity. Selling the extra to the power company. No battery storage system or anything else. Run off of my power when I could and theirs when I can't kinda thing. A decent generator isn't cheap by any means. The companies selling em sure made it sound good. But that's why you don't see more personal setups.

Like this storing heat idea. May sound good up front. And it may well work. But like with my basement. How much is it going to cost to break out the old concrete (I'm too tall to raise the floor) buy the materials and install the system and then re-pour the floor? Then what's the wind genny gonna cost. At 63 will I ever break even or am I just spending money to make an environmental statement? Kinda like here. When it's 30 or colder electric cars don't work well at all. So it's a 6 months a year car here. So about the only folks here with one have it to make a point and it sits unused for 6 months. Awful expensive statement.

Just questions I have.

Rick

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The concept I am wondering about is not intended as a retro fit solution. It would be for a new building or a retro-fit for a hot water radiant system in an existing building.

Some folks say that a hot water radiant heat floor system is one of the most comfortable ways of heating a building. I'm sure there are folks on YT who have them and can confirm this one way or the other.

The home where I live now sits on an unheated slab, with forced air duct work in the attic. In my mind, this is one of the worst possible ways to heat and cool a home, but it is a cheap way to build so there are a lot of them around. BTW, we bought it.......somebody else built it.

Back to the radiant floor system. If you are heating water anyway (heat = energy) the idea is to use something like a 2000 watt (or larger) wind generator wired directly to a hot water heater with DC heating element to heat or preheat the water in a storage tank.

Concept works like this, except replace light bulb with heating element.

https://www.youtube.com/watch?v=SgAMX0U_H88

Once water is hot enough, pump kicks on to send the hot water into the slab, where the energy is stored in the slab as heat. This way the slab is the storage mechanism for the generated power vs. a bank of batteries. My view is there are not enough lead acid, AGM or other batteries around to make these wind and solar deals possible.

And I understand the nature of wind relative to heights, etc. I'm sitting on top of a ridge that is the highest point for miles around. When these winter fronts pass through, you can hear the wind outside moaning like a sick woman. I've seen times when it would lift cushions out of the lounge chairs inside a screened in porch and plaster them against the side of the wall. In many places like this, the energy is there.......I'm just trying to find a way to take advantage of it. Won't help me, but it might work for someone else.

There are quite a few off-grid folks, who have PV arrays and a wind turbine, who use a resistive heating element as a dump load once the batteries are full. Often they put this dump load into a water tank.

So, how do you get that energy back OUT? What you end up with is WARM water or concrete.

In order for the stored thermal energy to be usefull for anything but heating a house in the winter there has to be enough of it there to boil water into steam for driving turbines when the wind isn't blowing and the sun isn't shining.

A much more efficient way is using the excess energy to power a winch, which lifts a heavy weight up a tower/silo, so when the wind stops blowing and the sun stops shining, the weight slowly falls and drives a generator (think like a recoil starter on a small engine, just really long) to provide electrical power.

Not wind no,but a combination of solar and wood gas.

Okay I'll bite, besides it cold and snowy outside so I'm not in a hurry to do my chores. I think you could do what your thinking, but I doubt it would make sense from a economics stand point. Wind turbines have some draw backs compared to solar. I don't want to discourage you, heck I say GO FOR IT! However, every time you convert from one type of energy to another there is significant losses. You're talking about going from linear wind energy then converting to rotary to electrical and finally to heat. Why not just get some of those new vacuum sealed solar water heaters, those things are the whip. I amassed all the parts to build a HAWT (horizontal axis wind turbine) several years ago, it would be a 1-1.5Kwh unit, but with the drop in the price voltaic panels, just the cost of a decent tower exceeded the cost of just buying additional panels. I thought it would be a good fit with my existing solar array, but alas, there the stuff sits taking up space in the shop. Of course after the dearth of sunlight we've been having the last three months I am seriously thinking of reviving that project. If or when I build it I do plan on using a hot water heating element for a dump load only. Also wind turbines require regular maintenance while the only thing solar panels require is to be repositioned twice a year. Well, that and some times I'll go out and brush the snow off them if the batteries are low and the snow hasn't shed off them. (I'm going, I'm going!).

Currently the future of alternative energy storage is focused on Vanadium by-pass or flow batteries. These batteries still have anodes and cathode plates to energize the electrolyte, but they have large reservoirs that allow the electrolyte to pass back and forth between the reservoirs depending on whether it's charging or discharging. These are huge batteries that depending size will be suitable for storing enough energy to power whole neighborhoods. Some of these batteries are already being beta tested. One suitably sized for individual homesteads IMHO is a foregone conclusion and will not doubt displace the Li-ion batteries being offered these days for residential applications. Currently for myself I plan on one more round of flooded lead acid batteries and see what is available ten years from now. After all, the advancements in technology is going on at a pretty rapid rate. Despite what a lot of "experts" that post on this forum say, alternative energy is coming no matter what. To put it in a perspective that might be easier for them to understand; consider aviation, we humans went from being earth bound misfits to landing a man on the MOON in just under 66 years! Heck we now have an airplane that is powered by sunlight. Sure it's not practicable right now, but how many people stood around back in 1903 and said "if god had wanted man to fly he would have given him wings"? Anyway, it looks to be letting up outside and the fire needs some wood.

JD

Would work great in the northern Virginia
Maryland area where all the long winded
politicians are full of hot air.

bwillet, I am not sure if your reply is tongue in cheek or Tuesday?s new funny? Have you ever seen a picture of the earth from the perspective of the moon or outer space. Do you really think that a few little tooth picks projecting from the earths surface is really going to screw things up? If such a study exists I would like to have a copy for light reading in the bathroom. Don?t get me wrong I really don?t think the tax payers should provide a nickel of the cost of those wind farms. I do know if any upheaval happens in our country causing a long term disruption of the power grid there will be some serious battles over the control of those wind farms.

here

That light bathroom reading would also have an appropriate secondary use.

New/old, no difference. Bottom line is it going to be cost effective?

That's all I'm concerned with. IF you still got 50 years and it's going pay for itself and then some in your life time? Good go for it. At 63? I doubt it.

Rick

(quoted from post at 07:48:13 02/13/19) [b:69a9c1344b]So, how do you get that energy back OUT? What you end up with is WARM water or concrete.[/b:69a9c1344b]

In order for the stored thermal energy to be usefull for anything but heating a house in the winter there has to be enough of it there to boil water into steam for driving turbines when the wind isn't blowing and the sun isn't shining.

A much more efficient way is using the excess energy to power a winch, which lifts a heavy weight up a tower/silo, so when the wind stops blowing and the sun stops shining, the weight slowly falls and drives a generator (think like a recoil starter on a small engine, just really long) to provide electrical power.

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Heat out? That is accomplished by passive heating of the building radiating up from the floor. In doing so, in my case, that would mean replacing about 1,000 gallons of propane. A direct dump into a hot water tank eliminates as many moving parts, storage devices, transfers, etc as possible. If the tank could be positioned below the slab, it might even setup a thermal siphon to make the transfer automatically.

I was thinking of heat only, but your idea of the tower weight as potential kinetic energy might work too. That could be tied to a heat pump for summer and winter use.

My concern with solar heat is in the dead of winter we only get 8 or 9 hours of sunlight and 80% of the time, its cloudy. Out here the wind is honking day and night and blows the hardest in winter months.

JD:

don't know anything about vanadium flow through batteries, but by the end of today, I will. Thanks for mentioning it.

For those wondering, I'm not an engineer, but am cursed with a curious mind. I also suck at thermodynamics. Cost me a full letter grade once in a chemistry class.

I thought about ways to beat the system over the years. After putting the pencil to the projects initial cost and all that goes with it, the annual
maintenance can be a real headache. I figured it wasn't worth it. Besides, I wasn't sure that all that initial effort would work. No idea as to how much
tweaking would be necessary and the practicality of that.

I read somewhere about a guy that dug a huge hole, filled it with rocks , built his house over the filled pit and used it to cool his house in the summer.
Never got in on how that turned out....

When you figure BTUs per unit volume/cost of petroleum products and compare that to naturally occurring potential solutions, my numbers don't justify
it.......quick point of reference is my 500 gallon Propane tank and my firewood pile. Only reason I go to the time, expense, and trouble of fooling with the
wood is that it feeds a 3' steel plate cube sitting in the middle of my house and the radiated heat is soothing. Course I could adapt a propane burner in it
instead of the wood and worry about what did I overlook that could burn my house down.....or blow it up!!!!!!

I'd guess it worked ok, if he could keep the rodents out of it. A fan at the bottom of the basement stairs worked well for cooling the house when I was young.

A big open space without the rocks would probably be more efficient.