Demand for Geothermal Heat Pumps To Grow 14% by 2015

[Fledermaus]

Dallas, Texas, United States – School districts across the nation are starting to replace conventional electric Heating, ventilating, and air-conditioning systems (HVACs) with ground source heat pumps (GSHP). Since the 1990s, when a handful of campuses installed the first GSHP systems, the technology has proven reliable and efficient with energy costs 30 to 50% less than the chiller systems of old. Many new schools now forgo the old roof-top units to install GSHPs connected to 250-foot-deep wells that transfer heat via water-filled polyethylene tubing.

“The earth temperature in our market is 70 degrees, so we have a resource that lets you keep a building at 70 degrees year-round,” said Don Penn, owner of Image Engineering Group Ltd., which has installed multiple GSHP systems since the 1990s.

Across the country, HVAC contractors are showing interest in learning about geothermal heat pump systems since schools and local governments have embraced the technology. Globally, installations of geothermal heat pumps are expected to grow from 2.94 million units in 2010 to 5.66 million in 2015 – a 14% increase, according to Dallas-based research and consulting firm Markets and Markets.

http://www.renewableenergyworld.com/rea/news/article/2011/01/geothermal-heat-pumps-demand-to-grow-14

[NNadir]

1. Oh good. Now we can have point source heat transfer fluids in our groundwater to go along

with our fracked rocks.

Feeling under the weather? Try a little ethylene glycol in your coffee.

The anti-science squad is certainly having a field day.

[Nederland]

2. Not necessarily

Most Geothermal HVAC systems (like the one I have) are closed loop systems and do not dump anything into the groundwater. The reason for this has less to do with environmental concerns than it does with practical concerns. Open loop systems (systems that take water from one well and then dump it into another) suffer from water quality problems. Well water is frequently hard, and the amount of water flowing through a geothermal system means even slightly hard water cripple your system after just a few years. There is also a trend here in Colorado to DX systems that don't use water at all...

http://geothermalhelp.com/index.php?option=com_content&view=article&id=83:open-loop-vs-closed-loop&catid=47:ground-loops-articles&Itemid=426

[saras]

5. necessarily and likely are two different things

They're only closed-loop if they don't fail.

Is that a reasonable expectation for something built these days, probably by a combination of big energy companies, the cheapest available Chinese manufacturing, and the building trades?

And personally, I'd like to see a large chunk of solid research documenting what effects may be caused by large-scale transfers of heat between the surface and a couple of hundred feet under. Especially research on the effects that we haven't considered because they're not obvious to us. Like the quality and quantity of research we'd have available if we'd taken the energy crisis seriously back in the seventies - you know, the fifty-year studies that look for currently unknown effects as well as the short-term studies of economic feasibility.

If there's one thing we've learned from a hundred years of pollution, it's that experimenting on the earth on a large scale is a stupid, dangerous way of doing research.

[Nederland]

8. It is obvious you don't understand geothermal

Given that a leak in a closed loop system often means several thousands of dollars in repair costs, owners (and installers who guarantee their product) have a large financial incentive to make sure it doesn't happen. That being said, even when there is a failure and a closed loop system does start leaking, it will dump 20 or 30 gallons of water into the soil and then stop working. Not exactly the kind of thing that causes an environmental catastrophe.

[oldhippie]

4. NNadir, I'm surprised at you .......

For one that is usually so technically correct, why would you think there would be ethylene glycol in a ground loop heat pump system transfer fluid? It's a closed loop system, but is not ever exposed to freezing. Water should work just fine.

[RC]

6. Ethylene glycol is used for corrosion control.

It lucubrates the pump seals better than plain water does. And then there is the bacteria problem to consider sometimes.

BTW, the proper term is "Ground Source Heat Pump". Geothermal is like Old Faithful, where you have an under ground heat source of a 100°+ to several hundred or more degrees.

[IDemo]

7. "Passive Geothermal" is a widely used term as well

http://www.energyboom.com/category/tags/passive-geothermal-energy

[Nederland]

9. True, but it stays sealed in the system

The only way ethylene glycol is going to get into the ground water is if you develop a leak. As I pointed out in the post above, owners and installers have a large financial incentive not to have leaks. The amount of ethylene glycol getting into the ground water from leaking geothermal systems has got to be trivial. If it weren't, geothermal systems wouldn't be popular because they simply would be too costly to operate.

[Statistical]

11. Most ground loops comes with a 20 year warranty.

It is hugely labor intensive to dig up a leaking loop, install new loop, and then retrench it.

Thus leaks are very rare. The pipes are actually pipes inside pipes to add layer in defense and top quality materials are used.

Labor costs are far more than the material costs so skimping on material doesn't make economic sense.
Save $500 per install using cheap pipes ending up costing company $8,000 in labor to reinstall leaking pipe.

[DemSigns]

12. Northern climates

Northern climates use glycol or methonal or other things to lower the freezing point in closed loops because the return to the ground loop can be below freezing and sometimes the supply from the ground loop is too but it is still moving heat out of the ground via the heat pump.

[txlibdem]

13. Ethylene glycol breaks down rapidly -- it's only dangerous for direct contact

Per the Center For Disease Control website:
What happens to ethylene glycol when it enters the environment?
The primary source of ethylene glycol in the environment is from run-off at airports where is used in de-icing agents for runways and airplanes. Ethylene glycol can also enter the environment through the disposal of products that contain it.
Ethylene glycol in air will break down in about 10 days.
Ethylene glycol in water and in soil will breakdown within several days to a few weeks.

How might I be exposed to ethylene glycol?
The general public can be exposed to ethylene glycol through skin contact when using antifreeze.
Accidental or intentional ingestion can occur because antifreeze is a sweet tasting, brightly colored liquid.
Exposure to ethylene glycol in air, drinking water, or soil is not expected.
People who work in industries that use ethylene glycol may be exposed by touching products such as solvents, antifreeze, and feedstocks that contain this substance.
Workers can also be exposed to low levels from ethylene glycol-containing products such as airplane de-icing solutions that have been sprayed into the air.

http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=85&tid=21

[madrchsod]

3. northwestern illinois is a perfect place for geo-thermal.

commonwealth edison drilled the granite bedrock and found that it would generate enough heat to turn a turbine. this was done in the late 70`s. the biggest problem they would face is building the towers...this area is the start of god`s country and the locals do`t want towers.

[txlibdem]

10. Too late to R but here's a Kick, thanks for posting this --something we all should know about

Here in North Texas you see a quite a few commercial buildings and homes that have buried air ducts under ground to provide cool air without having an A/C unit. There are issues with water condensation and possible mold growth that require periodic maintenance, basically running a string through the duct with a vinegar-soaked towel tied to it so it both cleans out dust and kills any mold. If you use bleach you will need to open up all the windows and run the fans for a few hours till the smell goes away; bleach is harmful to breathe.

[Odin2005]

14. My high school uses that very clever.

[Kennah]

15. Perhaps this is a stupid question ...

... but why don't GSHPs use propylene glycol? It is my understanding that propylene glycol is food safe and used in solar hot water systems.

[Statistical]

16. EG has far superior heat transfer properties than PG.

The thermal energy of earth is rather diffuse which is why EG is needed for good efficiency.
With solar hot water systems the suns energy is concentrated into a more intense form.

The more concentrated the energy source the more inefficiency you can get away with.

EG is better in two other important properties. EG lowers freezing point more for a given concentration. This means you can use less EG and more water getting even higher heat transfer rates (water transfers heat better than EG or PG). It takes higher concentration of PG to get same level of freeze protection resulting in higher costs and lower heat transfer rates.

EG also has a much lower viscosity. It puts less stress on pumps. Important because since ground energy is diffuse you will be pumping a lot of working fluid.

[txlibdem]

17. Isn't there a food-grade oil that would work equally well?

I thought I'd read that some of the CSP (concentrated solar power) plants use a food grade oil like Canola Oil or something. Couldn't a geothermal heating/cooling system use that instead of EG? (cost would be minimal since it's only 40 gallons of fluid we're talking about here)

Here's a Maine company that uses PG:

Typically, in a CLVB system, we drill 3-4" wide holes, about 100' in depth about 20' feet apart, until there are enough vertical bores to handle the capacity of the installed heat pumps plus the heat loss of the building. Our design software calls for about 150' of borehole per ton of heat pump when drilling into granite. We call this type of installation a "Mini-Borefield".

Into each of these holes we drop a loop of 3/4" HDPE pipe. The HDPE tubing is heat fused to IGSHPA procedure and the bores are grouted using special Bentonite Geothermal Grout to provide maximum heat transfer. The system is then filled with a 15% food grade propylene glycol anti freeze/water solution for maximum thermal transfer efficiency and freeze protection.

http://www.evergreengeo.com/welcome.htm
**note: CLVB means "closed loop vertical bore"

Here is a Minnesota company that uses PG:

The closed loop system is a series of wells or loops. A food grade glycol solution is circulated through these pipes to transfer heat from the ground to the home. The solution then goes to the heat pump, which transfers the heat to the home.

http://www.lyon-lincolnelectric.coop/Products/Ground_Source_Heat_Pumps/index.html

FYI, I did the google search: geothermal heat pump "food grade"

It sounds to me like you might be able to shop around and find an installer who will use food grade glycol instead of the toxic kind. Maine and Minnesota get some of the coldest winter weather in the US so I don't think EG is needed, even in the northern climes. Just some "food for thought."

[Statistical]

18. Yeah you CAN use it. Just be aware the thermal efficiency is lower.

Thermal efficiency is how effective the medium is for transfering heat.

This is why water at 100 deg "feels hotter" than air at 100 deg. The water is more effectively able to transfer heat energy from the water to you. Likewise water at 20 degrees "feels colder" than air at 20 degrees. Your body is more effectively able to transfer heat from your body to the water.

A system with lower thermal efficiency will still have same/similar indoor unit but it will require a larger thermal mass. In essence the ground is a giant heat energy battery. Less efficiency means you need a bigger "heat battery". The way you achieve that is with more piping. That adds cost.

EG in the environment isn't particularly dangerous. It breaks down in about 10-20 days. Still if it something someone is concerned about it is an option.

[txlibdem]

19. Agreed

I think that's the choice I would make, especially if I got my water from a well on the same property.

The extra piping and trenching wouldn't be as much of an issue for me because I'd be doing it all myself. I get giddy like a kid just talking about operating those big-ass machines. Is that so wrong?