Geothermal vertical loops

Bushman

I am located on Georgian Bay north of Parry Sound. We had a geothermal system installed utilizing lake loops.This was unsuccessful due to lake conditions. Presently investigating vertical loops to be drilled through granite. Two options with no clear answer which one is best.

1) drill more holes around 150 ft deep using 3/4 in pipe or

2) drill fewer holes around 350 ft deep using 1 1/4 in pipe

Can anyone give me the pros and cons of both please?

nicholas bonham-carter

Finding alternative heat sink

Why was the lake installation unsuccessful? Does it at least work during any season in the year?

Several systems have been described here, using the North Sea as a heat-source/sink, so why not a lake?--NBC

Bushman

geothermal vertical loops

I believe that the lake loops were unsuccessful due

1)water depth

2)insufficient water temp differential

3)insufficient pumping capacity

icesailor

Insufficiencies:

Those reasons don't make sense. It (the lake water temperature) can't be too cold for cooling, the lake water at some point in depth can't be lower than 39 degrees, no matter how much Ice is on the top, and if you can pump water to the moon with a big enough pump, you can certainly pump it out of a lake. How high is the house above the lake? Was this system ever run? Or did someone just tell you that it wouldn't work?

Give us more information please.

icesailor

Drilled Wells:

That makes even less sense to me than the fact that the old system didn't work.

Does anyone close to you have Geothermal wells drilled? Are there any 150' or 300' wells drilled for water wells? Has anyone ever taken any ground water temperature measurements at the bottom of the wells?



What exactly are you trying to do with this Geo-Thermal system? Heat? Cool? Or both?

Jamie Hall

Say again, please?

Lake Huron -- and Georgian Bay -- does sometimes freeze over.  But it does not freeze to the bottom.  As has been pointed out, at some depth -- and probably not that far down -- you will have lake water at a more or less constant 39 F (4 C).  From this a properly designed geothermal system should be able to extract all the heat it needs to heat your property or, conversely, reject all the heat you need to manage to cool your property.



There are two approaches: a closed system, in which you have a system of pipes in the lake (probably at or very near the bottom) with sufficient surface area to extract or reject the heat needed, or an open system, in which you simply pump lake water through your geothermal system heat exchangers directly.  Unless you are in a particularly grungy area of Georgian Bay, I would think the latter would work just fine.



So the question is -- why was the system unsuccessful?  What, exactly, were the lake conditions which caused problems?



I have not drilled wells in the granite in that specific area (if it is granite?) but in general wells in igneous or metamorphic rock has rather poor yields, and may be quite unsuited for open system (pump the water out of one well and back into another) geothermal.

Bushman

geothermal loops

First I would like to thank all that are responding to my question.

The system has run but not when the lake froze over , In moderate outside temp it worked. The system has 2 heat pumps one is a 6 ton triple function that will do cooling hydronic and forced air heat . The second is a 4 ton single dedicated to hydronics. When the system shut down the inside piping and helo pumps were iced up and the heat pumps fault indicated poor water flow. It is a closed system with 2 heat exchangers sitting on lake bottom 150 ft out in 10 to 12 ft depth. The house is not high above ground. I hope I covered all the questions

Jamie Hall

OK -- let's think about this

Your lake water heat exchangers are 10 to 12 feet down, so in the winter time they are in water which is about 39 F -- 4 C.  In order to heat your facility, you need to extract the heat from the water in your loop going through the heat exchangers and raise it's quality (that's the job of the compressor).  That's going to cool the water coming from the lake -- the heat has to come from somewhere, after all; there's no free lunch.  So the return water to the lake is going to cooler than 39 F.  Problem: you only have, at most, a 7 F temperature difference to play with (actually, you'd want to not use all of that -- say 3 F temperature difference, max.



Now the the heat which you can extract is a function of the temperature difference and the flow rate, just exactly like hydronic heating -- same formula.  And, like hydronic heating, to get more heat you either need more flow or more delta T.  You don't have the option of more delta T, so you need more flow.



I haven't seen your installation -- obviously -- nor have I seen the design documents, nor the controls.  From the sound of things, however -- based on what you have written -- it sounds as though you need three things: more flow in the lake loop -- probably a lot more flow -- and, most likely, bigger heat exchangers in the lake; you are working with a very small delta T on those heat exchangers, so you are going to need to move a lot of water.   You also need a control logic which cycles the compressors off when the temperature of the return water to the lake drops to some low value -- I'd pick somewhere around 35 F or 2 C as the minimum.  That way you won't get the freezeups you mention.

Bushman

geothermal vertical loops

thank you for your input I will bring that forward.

hot_rod

lake loops

would be my first choice if that can be salvaged. Could be the piping to and from is undersized even if you could increase the lake HX. You really need a qualified designer to start with a load calc, and system design. Most of the GEO manufacturers have fairly simple programs to do calcs for you.



Perhaps start with a search for GEO associations to get a lead on a nearby designer. It's helpful to find someone that knows the "lay of the land"



In my area the DNR limits GEO wells to 200', you might check to see what is allowed in your area.



I'm surprised that allow lake loops in the bay?

Bushman

Geo thermal vertical loops

Presently no permits required for a closed system I have spoken to 3 different companies and one couple coves over cottager with a lake loop. All same response Lake loops are and do not work in Georgian Bay It would be great to have it functional but too many negatives

icesailor

Lake effect Ice:

Jamie, the rule in physics the world over says that when the entire lake freezes over completely, the bottom of the lake is 39 degrees. From the experience of we ice sailors, we know that if there is a lake with 12" of frozen ice, with an open spot, there may be a spring that the water is warming the surface locally. Also, the bottoms of deep lakes can be in the actual flowing groundwater and warmer in the deepest spots than in shallower spots. There is also the issue of flowing water under the ice. A stream fed lake can have thinner ice where the water is flowing that in areas where the water isn't flowing. You can also find a tidal influence in large lakes like Lake Huron or Lake Winnipesaukee in New Hampshire.

Then, you get into the issue of heat gain/loss from the rise of air temperature and water temperature. If you get a lot of radiational cooling at night, the surface water gets much colder than the OAT that is 2' above the ice surface. But the underside of the ice plate will always be 32 degrees. If the plate is 12" thick, and the OAT is zero degrees F, 6" down (the middle of the plate will be +16 degrees F.

There is no way that that system shouldn't have worked if it was properly sized for fluid flow. Especially for AC. Most hybrid systems need back up systems for one side or the other, no matter what.

icesailor

Lake Loops don't work in Georgean Bay:

I'd like to know the reasoning behind that statement. Is it because of continuing poor design and it has become a local Urban Myth?

If you site a power plane next to a lake and suck water out of it to cool the power plant, it is a heat exchanger. Unless the lake has a design that doesn't allow enough cooling and warms up, it is no different than what you are trying to do.

If the Georgean Bay water quality is nasty and will foul the exchangers, that's another issue. But should be confined to WHY it won't work LONG TERM. But not why it won't work.

icesailor

More on Georgian Bay/Lake Huron:

A look at Google Earth shows some interesting features.

For example, around the town of Big Bay, you can see an interesting feature of lakes that ice up. The ice picks up sand and the expanding ice moves it on to the shore. When the ice melts, the sand drops off and the shore gets shallower. The water will drop off quickly at the edge of the shore. There are homes built along the shore to the right (North East) of the town. There are channels in front of many houses. They are either to get boats into deeper water, or trenches dug for water pipes. I guess a really big problem in the winter time with the need to cross large length of frozen ground would be to keep the water flowing and not be having to waste vast amounts of energy just to get warm water.

The farther North you go, the better Geothermal cooling works. The farther North you go, the worse Geothermal heating becomes. You can buy an awful lot of Propane for the cost of drilling a couple of deep wells. A view of the area shows the practical limitations of using the lake for geothermal heating. The limitations aren't because the science is bad. The on-site situations are bad. Someone should have explained that to you.

I'd be interested to know what their rational is.

icesailor

Lake Ice:

Jamie.

If you have any interest in ice and lake ice, here is a long, comprehensive explanation of lake ice. Take what you need and leave the rest.



http://lakeice.squarespace.com/

Bushman

geothermal vertical loops

Big Bay is quite a distance away from where I am. Although Lake Huron and Georgian Bay is the same body of water there are significant differences.The eastern side of the Bay where I am a little north of Parry Sound is mostly a terrain of rock Granite. Actually the home Is built out of a hole that was created by blasting.It is good quality of water but prone to huge water level fluctuations and wind.A friend who works at a water pumping station stated that last winter at a depth of 140 feet the water temperature was consistently 1 to 2 degrees above freezing

nicholas bonham-carter

Cold water from the well

If the underground water is so unbelievably cold, then the benefit of drilling a heat sink well would be nil. It might be time to install a wood stove or propane boiler., to make up heat during the the colder months.

Were all the lake loops installed by the same person?--NBC

Jack

If the system works other than the very coldest months of the year

Before I threw the well drilling cost into the equation I'd look at methods to augment the supply water temp. What about installing a boiler with a buffer tank to help out on this. All he needs is about 20* or so temp rise to get the HP in operation.



The comments on poor heat transfer in rock is correct. Years ago there was a big geothermal project in the Reno area. It was a "hot rocks" project. It worked fine until they had depleted the rocks temperature. The heat transfer to the cooled area was glacial in pace. End of project. In a well of this type you also have to look at the "flow gradient" across the well. Klamath Falls, OR has geothermal resource and everyone heats their homes with a hair pin of pipe in a well. That same system in Calistoga, CA where I lived would not work. The hot water in Klamath Falls flowed underground, and replenished the resource. Calistoga is on a lake of hot water and the water has to be pumped.



I wouldn't't spend the money on the wells. It may be good money chasing bad.

icesailor

Locations:

I was only commenting on the location of Georgian Bay. The fact that I picked Big Bay was only that it was a spot I randomly picked from Google Earth.

The fact that it is almost 32 degrees at the surface in a well doesn't change the fact that it will be close to 39 degrees in the bottom of the water column. The heaviest water will be at the bottom of the column with the lighter (warmer and colder) at the top. Water has its maximum density at 39 degrees F.

No matter where you go on Lake Huron or any other Great Lake, if the surface is frozen over, it will be 39 degrees at the bottom of the lake. But back from the shore, the farther you go from the shore of the lake, the groundwater will be warmer. Because the ground gives up heat to the water. And the groundwater is higher in elevation than the level of water in the lake.

I did some "afterwork" in a large public building recently where the entire building was done with Geothermal heating and cooling with no back up. It doesn't work well because at the extreme ends, there isn't enough "nuts".

They have 5-6" wells with 160 GPM worth of pumps (32 GPM, each). That's close to 80,000# of water per hour. If you can pull 20 degrees out of the water (55* to 35*), you have about 1,6000,000 BTU's available. But the wells have to be big enough to have a high enough flow of water and far enough away from the water source (the lake) to have the warmer water. The lake will always have a lower elevation than the groundwater in the land. The water in the ground is ALWAYS flowing toward the water body. Whether it is the ocean or a lake. The land under your property is probably igneous rock. It is probably heavily fractured and compressed from ancient glaciers. That's where the water is. But at what temperature. The farther North you go, the colder the groundwater is. It may not be warm enough to heat your home in the coldest months. But it will work in the Spring and Fall. Even if you can't practically put well suction and return pipes into the lake, you are still using the lake because it is close to you and effects the temperature and flow of groundwater.

I'd be interested in how the wells are drilled. The cost of drilling may just make the cost of that source of energy just too expensive. Any time I ever had people interested in these alternative sources of energy, the cost was so high that they went another way. Consider the cost of electricity to pump all that water to heat your house.

icesailor

Latitudes:

Parry Sound, Ontario. Penobscot Maine and Saint John, Maritime Provinces, Canada are on the same approximate Latitude.



Maine and the Maritimes are warmer because of the ocean and the Gulf Stream.

That part of Canada is cold because of the Artic High that spends the winter over Canada and Ontario. Part of that Polar Vortex thingy.

Bushman

Geothermal vertical loops

Yes the lake loops were installed by the same person. The drilling quotes I got for a 19 ton system are

1) 10 wells @ 150 ft for $3000 per totaling $30,000

2) 3 wells @ 350 ft for $6,000 per totaling $18,000

Bushman

Geothermal vertical loops

sorry typo 10 ton system