DOES GEOTHERMAL MAKE ECONOMIC SENSE? 4

[08201950]

I'm an architect in Toronto. My client wants a very large house built with geothermal heating and cooling. The house will have 12,500 sq.ft. of finished space, 10 to 20' high ceilings.
In Toronto in winter, the average earth crust temperature is 45 degrees. Some geothermal jobs I went to see were extremely elaborate with installations (in houses) costing over one million Canadian dollars. The electricity bills are in the realm of $8000 a month in the winter.
Does it make more sense to install five or six high efficiency heat pumps in a large house than going geothermal?

 

[racookpe1978]

Only place geothermal energy "production" really makes sense is when you're almost directly over the "hot spot" - the volcano basically.

In other words, trying to HEAT your building from the earth's heat will almost certainly fail. (Consider you need to get water pumped down hundreds of feet siply to get to 110 - 120 degrees; and the very deep (thousands of foot) diamond and gold mines that require cooling water for survival would need "regeneration time" to stay hot if you keep pumping cold water down - across a pipe link somehow - and back up in the same place continuously.

COOLING with the earth as a heat SINK does make sense - for exactly the same reason. Shallow depth then is more favorable in a cold climate, very low drilling cost, easy heat transfer with the ground water "flowing" across the shallow pipe field, easier maintenance and installation, and favorable heat exchange between the hot water from the heat pump and the relatively constantly cold ground in Canada.

 

[j79guy]

racookpe1978: Any ground temperature above +5C. will work effectively as a heat source for domestic heating. I have geothermal heat in my home, with average winter ground temp at +5C, and it works just fine.
(Northern British Columbia. 2400 Sq. Ft home, 65,000 Btu geothermal unit. 6 X 300' of 1/2" copper line loops, buried 14' below ground. All-up cost of heating system, $22,000.00 Cdn.)

08201950; Heat pumps too make sense, IF the air temp is above +5C. Colder than that, and you need the primary freon heat exchange medium below ground. In Toronto, your average ground temp should be around +6 in winter, so absolutely, geothermal heating makes sense. It begs the question, why wouldn't you? Go a Google search for Nordic Geothermal, located in New Brunswick.
The newer technology geo units use copper loops in direct contact with the ground to eliminate one heat exchange. (The freon runs directly in the copper ground loops.) This simplifies the systems considerably.

On another note a large majority of all John Deere farm implement dealers built over the last five years, have all had geothermal heat installed, as a company policy out of Peoria Illinois. This includes dealers across Canada.

Robin Sipe.

 

[08201950]

All the geothermal experts I spoke to recommended drilling vertical holes 300' to 400' deep. I got quotes in the range of $60,000 to $80,000 just for drilling. (We are building inside the city of Toronto.)
Furthermore, you are using electricity to extract that tiny amount of heat from the ground source. And electricity isn't exactly cheap, clean or efficient.
I hear people rave about geothermal heating so much, but how does it make sense?

 

[danberry]

I recently evaluated the simple payback period for a residential geothermal heating system. In my opinion, 17 years was way too long, especially since maintenance costs were left out of the equation.

You may get different results. The point is: you have to do the math. Get firm quotes and power consumption numbers. Its hard to tell how much a big house owner is willing to pay for bragging rights on his green geothermal system.

 

[EdStainless]

Two different cases, the one that racookpe referred to where the ground is hot enough to actually provide the heat.
The second is what j79guy is talking about where you use heat pumps and instead of working from the air outside you work from the ground which is warmer (in the winter, and cooler in the summer, both are more efficient).
Wells are compact and warm, but very expensive and require pumps and heat exchangers.
How much land do you have? A subgrade system is a lot less expensive, but requires space.
You well prices sound high, even in $C.
If you need to drill you don't need a separate hole for each heat pump. It would be more cost effective to drill a larger well and put multiple loops into it.

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Plymouth Tube

 

[08201950]

Our lot is small compared to country lots.
Vertical drilling is unavoidable.
Geothermal is all the rage right now in Toronto.
Drilling companies seem to have fixed their prices.
The quotes to drill between $60,000 to $80,000 are real.
It shows how absurd it can get when environmental issues become fashionable and political.
Apparently drilling one big hole doesn't work because the ground temperature is not high enough in winter (in Toronto).

 

[08201950]

Furthermore, it seems Geothermal and electricity always go hand in hand.
Without electricity, there can be no geothermal energy.
Am I right or am I missing something.
I can see geothermal can work if the ground temperature is high enough so that the heat can be easily extracted.
But in Canada?

 

[racookpe1978]

I think we're (all) confusing "geothermal" (actual power or hot water production from under-the-earth sources) as a term with a ground-earth-water electric HEAT PUMP heat dump/heat source.

A heat pump's source of ENERGY is strictly from the power grid. It's ultimate heat dump (when used as an air conditioner) may be the earth, or can be the air around the heat pump housing. The earth is a much more efficient heat dump (cool temperature source) - but as noted above, much more expensive for the drilling and piping.

In winter, the eath again is an effective source of heat energy for the heat pump, but the heat pump's POWER comes (as always) from the grid. NOT from the earth.

 

[btrueblood]

I know that in the Vancouver/Portland area, several large buildings (hospital sized) began using geothermal heat pumps. The first user was located near the top of a hill, and drilled a shallower hole, than subsequent users. As more users came "on line", the water table dropped, and the early user started to experience shutdowns...

 

[j79guy]

Electricity here (North East BC) averages 7.26 cents per kW-hr, for domestic use. Is electricity "green"? No, however I do live next to a 2.9gWe hydroelectric dam, which although the North American grid is interconnected, and gets a lot of it's power from coal fired plants, I take a bit of solace that "my" electricity isn't producing as much CO2 as in other locations.
Vertical bore holes here cost $1000.00 Cdn. per hole @ 400' deep. Sounds like they are raping you in Toronto. (Typical small bore hole, 400' deep will support 1 ton of heating/cooling, give or take depending on soil composition, ground water, ect.)
Back to the OP. does it make sense? Determine "sense". If you want bragging rights, and reduce your CO2 footprint over a traditional natural gas heated home, then yes it makes sense. From a pure economic standpoint, well, it depends. Sounds like your client doesn't really give a rip about the cost, (12,000 sq foot home in Hog Town?) or payback time, so why not go geothermal?

Robin Sipe.

 

[08201950]

An architect in Whistler B.C. got quotes for geothermal system for his 3000sf home - all came in at around $90,000. So he decided to go conventional.
Why do prices vary so much.
I've heard people got their geothermal HVAC system for under $10,000.
In Ontario, only a small portion of our electricity is from hydro, the rest is from nuclear and oil. I don't think that's too 'green'.

 

[EdStainless]

It doesn't matter if all of your electricity come from Coal. A heat pump system will result in less total emissions during cooling season. Big power plants are so much more efficient that it does make sense from an environmental point of view.
As for heating, you can use 97% gas furnaces and probably actually have lower emissions. I would have to look at the COP of modern heat pumps to see.

As to the cost, I put such a system in 15 years ago and I won't tell you how little it cost me. They ran city water out to us and I had an existing well that I could use.

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Plymouth Tube

 

[MJCronin]

To mitigate eco-guilt......

perhaps an advanced wood-burning stove ( yeah....I know...CO2) instead of an electricity gobbling system ?

Wood is renewable.....????

 

[mtngreen]

If you're looking at geothermal for a residential application consider using a direct exchange geothermal system. Rather than pumping water for the heat source/sink, the refrigerant is coupled to the ground.

Search Direct Geothermal Exchange for details.