\"Free\" enrgy for Snowmelt

John Myrtle

Just dreaming... Why wouldn't a ground loop (not a heat pump) circulated with a snowmelt sytem not work? If a mean temperature at 6' below grade ranged 45 to 50 deg., proper flow rates etc. Maybe something of a constant circulating system when the ambient temp. dropped to 40 deg.? The snowmelt sytem would be running off of very small Delta T, but with a proactive constant circ. enough energy? Obviously not for public "must melt" situations, but for residential drives & walks? Could be ridiculously simple system. Humm, maybe I should get another beer.

Rich W

Free

It sure will. Just get out your books and charts and do the math. There is no doubt it will work with the proper deltaT and collector area. OOPS! I was talking about books and charts. Sorry, I thought I was on the CO thread

P.S. What about a two stage set-up and a second loop in the drive for "must melt" situations? I like it John.

hydronicsmike

hmmmmmmm...

...I like it too, if it is physically possible to pull those kind of BTUhs out of the ground. It seems that it might be shy of a few hundrets of thousands of BTUhs, but thats just an uneducated guess without looking further into it.

If you ever do give it a shot, please let me know.

Having said that (and enjoyed a beer too while I am reading this)I wonder if it may be worth while to use Ashphalt for Driveways for snowmelt in the winter (would suspect much quicker heat up rates as concrete) and then in the summer as a type of solar collector. With Ashphalt being dark surface, could there be possibly enough heat from within the slab that may be high enough to use it for radiant if the energy and heat is stored in a Storage Tank? Thinking free heat in shoulder seasons like early fall or late spring. What do you think of that? Snowmelt in Winter and Free Heat in the Summer. Would Asphalt also not be cheaper to run in the winter, as it is also able to act kind of like a thermal mass if it was hit by the sun before the clouds rolled in and it started snowing? Where are the Ashphalt Snowmelt Guys??

One of the reasons I love this site is because people like yourself come up with ideas that may seem crazy for some, but others like myself value very much. Long ago, most people thought it was crazy to shoot people to the moon or anything into space period.

Thanks for sharing.

Mike

leo g_13

Mike,

when I was a kid, some neighbour had done something similar. He put loops under his driveway and heated his free standing pool during the summer that way. He also claimed to have run some of the tubes under the dirt in his garden, so that he could extend his growing season. Don't know about the latter, but the pool was definately warm!

Leo G

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Mitch_4

DAG NABIT!!!

I have to redo my cement drive and I LIKE IT!!!

May not be as soon as I would like, but I'll put one in and let you guys know.

WAY cool thinking outside the box!

Mitch

Bob Gagnon plumbing and heating

similar job

reported in this months R.P.A. newsletter. they ran pex through a part of highway to cool the asphalt in the summer and stored the heat underground to be used for snowmelt in the winter. Bob

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J.T.

This is great!!!!

I'm in the middle of purchasing a 1940's cape cod and we'll be adding a driveway in the future. I was thinking of putting tubing down so I could have "free" hot water in the summer. How hot is the asphalt when they put it down? Can the tubing handle this, I wonder?

leo g_13

just gotta

be there and keep a good flow of COLD water running through as far as I've been told. Was thinking about putting some tubing under the parking area that I want to get installed this year also (want to try that garden thing). Maybe M.E. will put will pop in and give us some advice as too the tubing and asphalt install.

Leo G

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jp_2

like hydro mike says,

run the circulator on sunny days to put a little heat back into the ground, or run it all summer.

might need to bury a whole lotta tubing.

hydronicsmike

Wow!

This stuff is simply amazing! Hope to read more about it...

Mike

Kal Row

i did some study of \"ground source boost\" geothemal...

the ground source btu "RATES" for snowmelt under load just aren’t there, unless you have a big buffer - like a pool 10ft deep under your whole driveway - remember where the term "ton" comes from - it takes 288,000 btu to melt a ton of ice over 24hr or 12,000btu per hour, melting, is a state change like, vaporization and requires a whole lot more btu – so “snowmelt” takes a whole lot of British guys!!!

now, if you had such a pool, and a drain back solar, and a liquid chiller/heater heat pump, that would be another story, in fact, if your house was all slab radiant, 110f supply, 90f return, then one sunny day, could still maintain high efficiency on the heat pump, over two cloudy days, including your snowmelt

If I ever build a house out of town, it will have just that, excavate the whole property, and lay in 1000’s, yes 1000’s of ft, in tens of loops, and build multiple septic tanks, on top to hold tens of 1000’s gal buffer water – I would not even put a boiler in the house, one propane or wood fired hydronic unit to boost the final tank if needed

The biggest problem with the whole setup, is controlling bacteria and algae, oh, just forget about it….;)

RoosterBoy

wow now thats something id love to see done. it may work my driveway is dam hot when the sun is out.

Bob Gagnon plumbing and heating

no bacteria or algae

unless the water is in direct sunlight. I had a solar storage tank that never got over 120 degrees for 2 years and it stayed clean. Bob

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Mad Dog

How about incorporating a solar heat panel

to supplement the geothermal? I've melted snow with 80 degree water running thru the tubing - took a while, but she worked. Good thinkin Dinkins! Mad Dog

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Mad Dog

Hey Bob, where are you located?

I've seen your trucks around NassaU. mAD dOG

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chuck shaw

What about

using it for snow melt in the winter, and heating a swimming pool in the summer? I know it isnt my original thought, but what an idea.

Chuck

ALH_3

Free

It might work if you live in Yellowstone park ;-)

45-50 degrees isnt going to be enough to melt snow. Not to mention the huge amounts of tubing that would be required to be buried underground. Then there's the issue of getting good contact between the disturbed soil and the buried tube......

-Andrew

Dale Pickard

Hee Hee

I think that he needs another beer, after reading this, I sure do.

Dale

Mark Eatherton1

Jeez Myrt...

We just had this conversation last week:-) Good to see you.

Numerous researchers have done studies on deep earth thermal storage. They've found that it is feasible to extract up to 80% of the thermal energy input back out of the ground. More info at

http://www.doc.ic.ac.uk/~mpj01/ise2grp/energystorage_report/node5.html

or Google deep earth energy storage.

You may remember the 13K square foot snowmelt system we did for Target stores in Silverthorne. I tried convincing the corporate engineers that we could run the system during the summer, and utilize water to water heat pumps and efficiently extract the solar heat from the glycol and use it to heat the water used in their 1 Hour Photo lab, and their food prep facilites and prove to the community that they're a Green company. Still waiting to hear back.

I don't remember who it was, maybe Heatboy, but anyway someone here was telling us that Mario Andretti heats his olympic sized swimming pool during the summer with his snowmelt system. If its good enough for him, it's good enough for my customers.

One of our best building contractors hired us 3 years ago to install the tubing for a snowmelt system on a spec home/castle he built. We mentioned to him that the snowmelt system COULD be used to heat the olympic sized swimming pool planned for the back yard. Guess what, he just sold the home this last week and the new owners want to move forward with the installation of the physical plant to make things work. Seems the clincher was the pitch about the snowmelt system being able to maintain his pool :-)

Last weekend, someone was asking a question about using the waste heat from a district steam heating system. The condensate leaves the system at 200 plus degrees F and HAS to be cooled down using potable water before it can be sent to the sanitary sewer. What a DOUBLE waste. THere's a system on the 16th street mall at the west end bus station that uses the waste heat from the condensate to maintain the snowmelt system. It's ALWAYS dry, and only costs the electric power for the pumps to operate, AND it saves the dillution water normallly wasted.

My idea, I have a customer that has a small water to water geo system we installed. He wants to increase the capacity. I want to install some evacuated tube solar collectors on his roof and send the solar heat down hole. This would increase the btu's available without having to increase the size of the well field. Think about how much free solar energy falls on the face of the earth during the summer months that goes un used...

Here's the skinny on the Dutch holding company doing snowmlet for free.

http://www.ooms.nl/english/pages/divisie_gww/road_energy_systems.html

Looks VERY interesting...

Lastly, I had a student that attended one of my 1 day Radiant Basics classes that as a young man help install a system in Wyoming. It was a heat pipe system. THe heat pipes were buried 50 foot deep. These heat pipes were connected to a snowmelt system incorporated into the concrete of a bridge that crosses over a creek on I80. He said it works great, until the wind starts blowing.

This same student invited me to see the heating system in his own home. On his detacched garage, he had installed 7 each 4 x 12 flat plated solar collectors. He had intentionaly thickened the slab in his garage to 18" thick in the middle and tapered it down to 6" on the edges. In this, he'd imbedded 1/2" tube at 12" OC. In addition to this, he'd installed 1/2" tube at 6" OC in the parking slab on the north side of his garage. All of this is ONLY solar heated. He raises Earth worms in the garage, so it CAN'T drop below 40 degrees F or his worms will die. He's never lost a worm, and he's never had to shovel ice or snow off the north side of his parking area.

SO, yeah, you could say it CAN be done... As Dan says, "If you can THINK about doing it, it CAN be done."

Nothing is impossible. It's just a matter of money and commitment.

See you at RadFest?

ME

Dale Pickard

Energy and Engineering

Sorry Mark,

Money and commitment don't mean anything up against the laws of physics. Engineering allows you to interpret those laws and project their meaning into the real world as successful works of engineering. Putting more money into something than it's worth is foolish, hence one of the more severe constraints on such works is always economic. Even things that can be done, shouldn't be done if it's not worth it.

The things adddressed in this thread are not at all mysterious and quite explicable from an engineering standpoint. A little engineering knowledge, some arithmetic and the back of an envelope can expose the silliness in this kind of compulsive design pretty quickly. I think that our perceptions of the limitation of the real world have been heavily clouded by a few decades of cheap energy.

Most often the compulsion shows up as a misunderstanding or disrespect for the laws of thermodynamics. For example, much of the stuff addressed here comes close to perpetual motion. If things were easy or cheap, we would already be doing them but they're not, and they won't be.

I followed your link, The dutch road conditioning system is free. It's a solar assisted heatpump, which is a common thing. It's a heat pump though, it runs on electricity at a COP of maybe 4:1, so it might bring electricity prices down to natural gas prices, which is a good deal, but only if you don't have access to gas but you do have access to electricty. The energy that's the heat pumps are moving back and forth is solar derived, and it's not free either, as the road was turned into a crude solar collector at some considerable expense.

If the Target store had a large seasonal pool, then using the parking lot as a solar collector for a solar assist might have made some sense. It might be done without heat pumps.

Using it in conjunction with heat pumps to elevate water temps for process water temps probable would not have made sense. Heat pumps that operate with output temps approaching 120 deg, do so at a very low COP, less than 2:1. As you approach 1:1, you are replacing some simple electric resistance elements with a complicated mechanical thing. You'd have to produce heat at better than 4:1 to beat natural gas prices. If Target has acess to nat gas, it would be preferable to use a gas fired boiler, which can produce heat without temp limits to the heat pump which would struggle to do the job.

If the process or domestic hot water load is small then there is no energy to be saved so you might as well put in an electric water heater. It's not worth a bunch of mechanical hoo rah rah to supply not much energy to the small load. You have to use energy to save energy.

Much of the talent in renewable energy applications lies in an accurate and realistic appraisal that leads to an appropriate and economically optimal investment path.

So, I say, all kinds of things are impossible, money and commitment are just silly human mental constructs.
There is no free energy.

There's no free lunch, money and commitment notwithstanding.

Respectfully,

Dale

Mark Eatherton1

Dale...

I guess we can agree to disagree.

Respectfully.

ME

Kal Row

i'm with you me, people are doing it sucessfuly...

so you need new physics

it the same old, every time religious people get into an arg about god and science -
the simple truth – we know zero about god or science!!!!

“there is no free lunch”??? you might be right, “the creator” may one day expect us to pay for all that solar energy (900w Psqft summer 450 winter) "them is ah lotah key-low-waah-ttsss" we are just throwing away

or how about the panama canal, as long as this planet is rotating, the pacific ocean pours into the Atlantic ocean a quite a clip, the central American power authority already has 13 turbine tunnels, we could put enough turbines there to power the planet indefinitely – lay cable across the Bering strait or microwave it via a space mirror to the eastern hem.


Fact is the only devices that should be using fossil fuels are aircraft, cars can be all electric – if you embed induction coils into major thoroughfares, and boats can have a ton of mini-windmills and tow 10 miles of thin floating solar-cells

Get real , It’s not science that stopping us dale, as always, it’s short term and sighted economics!!!!
Not to worry, we will certainly close the barn door after the horse runs out!!!

Or we can switch to alternative + electric now, so that the gas companies don’t kill us with panic shortage price gouges later

Bob Gagnon plumbing and heating

we have to do it

just because it's not cost effective now, doesn't mean we souldn't do it. We will find ways to make it cheaper and better, and as fuel prices increase and fuel supplies dwindle, these systems will make more sense. Solar and geothermal is as close to a free lunch as you can get. And all the really cool people have solar collectors on their roofs! Bob Gagnon

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Bob Gagnon plumbing and heating

Mad Dog

I'm located in northern Massachusetts. I just read your find a professional ad, nice job. I thought I was the only one still using lead and oakum. Bob

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Gordy

What is free is what the earth and space can replenish. Wind, Solar, GEO, waves others. What is not free is what the earth can not sustain from over useage and its Bi products. You are right on Bob wish everyone would think like that. Past civilizations have risen and fallen because nature could not sustain their over use of the natural resourses at hand.

ALH_3

Free energy

So soon we'll all be using ground source heat pumps powered by windmills and PV panels? After reading through your post many times I still cant tell if you're supporting ME's point or trying to disprove it. You still cant snowmelt or heat a home with 50F water without a heat pump. That's where the laws of physics and thremodynamics come in. Until they start giving away solar panels, windmills, and batteries those energy sources arent free either.

One of the biggest problems with electricity is storage. These "free" energy sources rarely are delivering power when you need it. (hydroelectric being the exception) The only heat source I know of that can be stored and is essentially free and somewhat renewable is wood. Perhaps we should start using pellet stoves or boilers.

There are people willing to deal with the limitations of these energy sources. The vast majority of people are unwilling. They want the heat to turn on automatically when it gets cold.

If you put 1V into one end of a wire and measure the voltage at the other end, it will be less than 1V. If you have a shorter wire it's closer to 1V than if you have a longer wire. If you run a wire from Panama to Michigan you're losing a lot of power to resistance.

I'm not sure I'd like to drive on a high voltage freeway. What if I would like to pull off the highway? Can farmers run tractors on electricity too? That might be a lot of solar panels or a very long extension cord.

I feel we should focus our efforts on conservation. That includes people not building 10,000sf houses for two people. What about all the fossil fuels being burned to generate electricity so people can live in insanely hot places like Phoenix? How is their insulation? Should state and federal governments help pay for insulation instead of just helping to pay to heat or cool inefficient homes? How many PV panels would it take to run an air conditioner on a pooly insulated house in Las Vegas in July when it's 90F at midnight? How many old, inefficient boilers are running out there? Should everyone have a solar pre-heat on their domestic hot water tanks? Think of the energy that alone would save. Maybe Halliburton will provide some money? ;-)

Alternative energy isnt going to let us live in the style we have become accustomed to in this country. We're going to have to adapt and do without certain things. Things like large snowmelt systems start to sound incredibly irresponsible. (not that they dont already)

Using natural gas to generate electricity to run electric water heaters and electric baseboard? That’s insane. Storage and transport is key.

-Andrew

Rich W

cheap

The reason things like this are not done is exactly because of cheap gas. Here in MI nat.gas went up 30%this year,30%last year and 20%the year before. What about five years from now? Snow melt isn't cheap to run or maintain. I snowblow a five ft. path in the center of my blacktop drive in the morning and the whole thing is clear when I get home. Atleast on a sunny winter day. I haven't done the math-seems like any extra energy would only help. Even if I had to add some collectors and a diff.temp. controller it would save wear on the boiler and gas bill. I'll admit that retrofitting the drive would be expensive- but if you were going to do it anyway...I still guess that buried tube,snow melt tube,collectors and controllers would be cheaper in the long run.If you need to melt it NOW, you could add an aux. loop and HX from the boiler.

Dale Pickard

That makes sense, as long as it's a seasonal pool, that you only use in the summer and you would heat it anyway.

Even then though, the episodic nature of snowmelting demand, coupled with the meager output of the solar system in the winter, would conspire to produce little output to snowmelt.

A better application would be to apply the output of such a solar system to another more constant load that will better utilize the energy collected over the whole winter and the swing seasons. Those loads usually are, domestic or commercial hot water first, and space heating second.

You can't use the output of the solar system twice and you will never size a collector array to do 100% of any of these loads in the winter. So there is really no point in going through the mechanical hassle of moving solar heat into such an intermittant, episodic and very large load as snowmelting.

The general rule is that the more efficient solar systems will contrive to use all the energy produced over the year and that the better solar applications are those in which the load closely follows the supply. As long as a building is under load, there is no solar "system" that is more efficient than a window that is gaining more than it's losing.

Dale

Dale Pickard

Well,

Those are the questions, how expensive is the solar system, how much useful and utilizable heat does it produce, how expense is "conventional" energy, and how long is the long run?

Framing real and appropriate questions and putting realistic answers to those questions is engineering. That information is available, you don't have to guess and wonder.

Dale


I'll admit that retrofitting the drive would be expensive- but if you were going to do it anyway...I still guess that buried tube,snow melt tube,collectors and controllers would be cheaper in the long run.

Dale Pickard

New physics?

Well, speak for yourself. Science is a word we use to describe the things that we can know. That knowledge can be demonstrated without need for belief.

God is a word we use to describe something that's not knowable or demonstrable. (some may argue)

It's interesting that you turn to science to answer these energy questions but then dismiss science when it doesn't tell you what you want to hear. Even when science is the only thinking that ever provides real answers to any questions. The only bastion or means of demonstrably objective thought and discovery.

If you only want to hear what you want to hear, try god.

Dale

Kal Row

solar and geothermal is demostrable science...

as for god:

"the creator" or whatever you concider the living universe to be: is shining on earth with the sun and has covered the earth with 4 fifts water - message is clear:
"natural sourced hydronics rocks!!!"

Kal Row

i wish ...

proselytizing liberal environmentalist hypocrite cooks, would spend some of THEIR money on this

e.g. take Barbara Striesand – telling everybody to use less AC while she runs lots of tonnage in her mansion!!!

Let her put up her megabucks, and I will give her a system with radiant cooling in the ceilings, dehumidification via conveyor driven solar dried desiccants, and the conveyor itself is solar driven, solar driven sterling engines that drive heat pump compressors for boost chilling or heating, huge underground hot and cold storage – huge battery rooms
With her megabucks and space, I can generate enough, to even add power into the public grid

Sure it’s not cost effective – but before she opens her mouth to do anything but sing, she ought to lead by example – I want that commi off our grid !!!

Just rabble rousing…she’s an entertainer…she should be able to take a joke

David Woycio

Solar applications

We have been designing and installing solar thermal systems since 1982 and the "trick" is storage. Sizing a storage tank for your loads (radiant, pools, hot tubs, driveways etc..) is key. Our storage tanks store water and are made of stainless steel. These tanks are heavily insulated (4" of poy-iso.) For domestic hot water heating the "rule of thumb" is 1.5 gallons/square ft. of collector area. Domestic water heating is on the higher temperature scale when compared to other loads. For a swimming pool we may go as high as 4 gallons/ sq.ft. All depends what the load temperature is. Driveways are tough because of they're inherent demand. Most systems that we set up first heat the house (hopefully radiant) and storage tank then any excess can be used to preheat the returns from the driveway before going through the driveway heating system. It's an added expense for equipment (heat exchangers, controls, pumps and plumbing) but if everthing is relatively close can be well worth it considering the huge utility expense for snowmelt.

When the solar array is in direct sunlight usually your loads are requiring the least amount of energy. It's when night rolls around that the stored energy is hopefully great enough to handle these loads. During full sun, a properly designed solar thermal heating system will handle the current loads and also raise the storage tank's temperature. Even in the middle of winter some systems will high limit (180 deg.) when we have a full day of sun. If there is snow on the ground or roof all the better because snow will reflect more sunlight to the collector array. Granted our climate (Denver) is quite a bit sunnier (301 days/year) than some others in the country the same rules apply. You guys back east just need to buy more collectors. By the way we have LOTS of used flat plates for sale it anyone is interested.

The higher utility prices rise the quicker the payoff for solar heating systems. Go OPEC!

hydronicsmike

MARK

I remember the Target Superstore you did. If you want, I'll help you out on the Controls side of things. You should and most definitely will be able to use some of the heat from the Slab in the summer as source for other, smaller loads.

Mike

Dale Pickard

There you go

That all sounds like pretty straightforward solar design, including the storage sizing. No perpetual motion involved.

I question the real efficacy of the driveway systems though. If you are doing space and water heating in the winter, do you really have the energy to provide anything but a minor fraction of the very large snowmelting load?

s it really worth the mechanical hassle to move heat from the storage tank to the driveway?

An optimally sized solar array would never provide anything close to 100% solar contribution to space heating. Maybe at best 40-50% after the dhw is taken.

Where does the energy come from for snowmelt?

Dale

Rich W

cheap

Since I don't know his details it's impossible for me to do the math. I don't think he wanted to do snowmelt for a Mall of America sized parking lot though. Melting snow was the original idea- not DHW and space heating. I don't know how much he gets, but snow starts melting well below 50deg. were I live. As I said before- use a second loop from the boiler for "must melt" times. When we bury tubing we use a power tamper for back filling- we get good contact. Also, I'm willing to wait 5 or 10 years for the break-even point- I know most people aren't. If the tube is buried around the perimeter of the house during construction you'd realize a big cost savings. Yes, digging a huge hole just for this idea is not cost effective.For "free melting" at the start and end of winter it could work with a blacktop drive.

David Woycio

billygoat22

how does water flow throught the Panama Canal from the oceans? The water to run the whole thing flows by gravity from a freshwater lake on top of the strait, down either side. Water could not flow uphill from either ocean.

If there was a tunnel under the landmass below sea level, that would work, I believe there is an elevation differential between the two bodies of water, so there would be flow.

But that ignores the environmental problems that already exist with organisms hitching a ride in ballast tanks over the canal. Look up "zebra mussells", quite a problem on the Great Lakes, they snuck in in ballast tanks and are now a problem for localities.

Kal Row

prevaling westerlys - just like the wind...

the central american power tunnels are level - the earth's rotation is doing it

Jack_21

Resources

Check out the Geo-Heat Center at the Oregon Inst. of Tech in Klamath Falls. Also, the CA Energy Comm did a bunch on analysis of various geothermal deposits in CA and compared performance of the various fields. It will take some digging perhaps but a lot of good info on ground heat transmission. Areas like Klamath Falls work well with a downhole HX. In Calistoga, CA the hot water had to be pumped as it did not have a flow gradient. Klamath Falls was a river, Calistoga a lake. Antoher thing I recall wasup in the Reno area there was a geothermal deposit that got cold capped by over drawing and quit producting. Due to the low Reynolds number of the soil. All this is over 25yr old info, but is very well documented. And, by golly, it wouldn't surprise me at all if there has been additional work done since...

David Woycio

Well.......

Actually we shoot for a 60 -70% savings on the AVERAGE heating loads for winter. Domestic hot water heating is not much of a load drain with systems of this size. 300 plus sq. ft. of collector area and 1100 plus gal. storage on a 3500 sq. ft. home. Set the storage tank to cut off heat to the driveway at say 130 deg. or so and you in business. Dumping heat into the ground when we have excess solar heat is a good thing. The ground becomes the storage "tank" and will hold temps. b4 the next snow. It helps if we have some perimeter insulation around the drive. Obviously if the drive is the size of Graceland it's going to be like pissin' in the ocean. But for lighter loads solar can provide "some" assistance. You have to do the heat loss calc. to see where you're at.

I guess it comes down to the final energy bill. If joe homeowner pays $100/mnth heating the home and $300/mnth melting the snow off the dirve I say heat as much of whichever load you can. We can even set these systems up to heat the radiant with solar as cool as 100 deg. then dump the remaining energy into the drive. The tank temp for snow melt can then be run down as low as 50-60 deg and still provide energy.

What REALLY works great is a solar - boiler - fireplace combo. Run the solar storage till depleted then light the fireplace for heat and supplimental heating of the solar storage tank via a fireplace hx. Talk about some nice BTU gains. 200-300 deg fireplace hx with about a 10-20 gpm pump and the tank picks up temp very nicely. Careful on how you set this one up, you're playing with fire, and some serious temp extremes.