Geo-Thermal Is this True?

Liberal Lenny

Hello Wallies, Today I read this article , the paper is from Martha's Vineyard. I have zero experence in Geo-Thermal, just #2 Fuel oil. Are these numbers right ?, I can get a 25,000 dollar system and it will pay me back in five years?

http://mvtimes.com/news/2007/02/22/geothermal_energy.php

Dave_4

Maybe

Or you could spend half that on new high performance windows, sealing up the house, and add a heat recovery ventilator and have the same or better payback. A geo-exchange system is not a "magic bullet". They are best when there is a good energy balance on the geo-exchange field (suck as much heat out of it in winter as you dump heat back in during the summer). You cannot use a geo-exchange field for strictly heating (or strictly cooling) unless the soil conductivity and other ground conditions will allow it.

They still use electricity to generate heating and cooling, albeit at a much higher efficiency compared to other forms of combined heating and cooling. In the NE US, most of that electricity is generated by thermal plants with a net efficiency of maybe 10% to get that Kwh of electricity to your plug (gotta burn 100 Kwh of coal or oil to get 10 Kwh to your plug in the house) so a gas fired condensing boiler in your house is actually more environmentally friendly when you compare it to a geo system on an overall basis.

Singh_3

Liberal Lenny

A lot of what is said is true , but..
What is not true, I can't see a five ton system, with radiant and DHW costing only
$25,000 to install. Most likely three times that amount.
I went to IGSHPA both in Albany,NY and at Oklahoma State University. It did not cost me $10,000 .
IGSHPA does not recommend copper exchange systems, although copper does have better transfer, for longevity, poly pipe is suggested. Notice the sand at the Vinyard, dry sand is one of the worst exchanges, I would make sure you really design, or have someone design the ground loop with care. You only get one chance.
Yes, what Geoff says is true, start with envelope. And, the fuel needed to generate the electricity is in-efficient. Not unless the install those windmills in the vinyard, but thats another thread.
I would like to see some REAL comparisons GSHP vs Mod-Con w/AC. (since geo does both) And all the efficiencies necessary to generate and run a complete system from power plant to house.

Perry_3

Before you complain about the efficiencies of power generation..

Look at the options.

Without that "inefficient" power generation and distribuiton system... Virtually no power for modern society.

I do not dispute that on average - the overall efficiency of electricity delivered to your door is about 16% (its not 10%). From a purly theoretical standpoint - which says that a power plants output is at about 33% thermal efficiency.

The problem is that you really can't do much better than that as the thermal cycle efficiency of most power plants is like 35% max.... (and no one has yet figured out a large scale more efficient system).

Another way of looking at it is that most power plants are 90+% efficient of what can be actually gotten from the fuel with that process.

Since almost half of the electrical production is lost in low voltage distribution (the wires that run arround town and your house) that makes it about 45% efficient.

Trust me -- if someone had a more efficient power generation process... that works as a large scale application - we would habe buildt it. There are some promising things in the future to eek it up some if you wish to stick with coal and oil power production.

Back to topic: Without the electrical grid - no one would be producing those solar cells or windmills either. They take power to manufacture too... Battery systems, inverters, windmills, etc... also are not really that efficient from a theorectical standpoint either. Just be sure you are comparing apples to apples..

Perry

Bernie Riddle_2

I could throw a rock

But If you read half way down, it say's it is "one of the first" on the Island>> If it is such an outstanding source, why isn't everyone using it [And don't say money, money is all there is on MV]

Plus 50° ground temps, sounds like it will take boiler running to constant preload the system?

mikea23

Geo works great

But like any hydronic system proper design is key.
A five year pay back wont happen its more like 7 to 10 but the larger the structure the faster the pay back.

50 deg ground temps are perfect for the system you arent using the loop to heat the home the compressor in the unit does that. The loop simply cools the refrigerant or warms it depending on the season.

Geo has taken off in the last few years we installed 2 systems in 2003 and 21 in 2006. But the upfront cost is high so you need a educated consumer to purchase it. Just like Mod cond boilers they took a long time to catch on and a spicific customer to purchase them.

Mike A

design

geothermal with vertical loops

What could be the biggest geothermal project is in Lawrence, MA. Will have 1.3 million sqft, using 1500 ft deep holes.

See article in today's Boston Globe
http://www.boston.com/realestate/news/articles/2007/03/05/grounded_resources/

Sidebar article says a residential geothermal retrofit is an estimated $20,000 to $25,000. Single well 1000' or less. Payback 5-10yrs.

http://www.boston.com/business/technology/articles/2007/03/05/system_can_work_in_single_family_houses_specialists_say/

I know northeastgeo.com and keyhvac.com in NH have installed several climatemaster.com systems.

More info at geoexchange.org

GMcD

Not Complaining

Just stating the situation. I accept that the electrical generation and grid system currently has this level of inefficiencies, it's "the way it is". I am just pointing out that it depends on ones' motivations for a geo system- to save energy? But how much energy would it save given that "big picture"?, and on a macro scale it may be likely more energy efficient in an area of high thermal electric generation to use a local high efficiency condensing boiler - less global emissions, and energy cost is still saved.

I think that global/macro scale energy efficiencies for those thermal generating stations can be directly improved by much higher efficiencies and conservation at the terminal end of the plug- if every house improved their energy efficiency, that would be a 1/0.16 = 6.25 times improvement/reduction on coal and oil use at that central generating station.

Keep up the great posts on the electrical grid, nukes and "source energy" - valuable stuff.

Mason

Geo payback

Geo's work well here in MI with 52`F ground temps, and the payback really is 3-7 years. I have MANY more than satisfied clients that Heat and Cool their avg 2000 sqft homes for about $65/month. The math doesn't lie.

Luke Lefever_3

same here

We have similar ground temps here in Northern Indiana as Michigan. Payback on a recent project was 2 year and 7 months assuming constant utility costs. We have had no luck with DX systems (direct exchange). Too many leak paths to keep track of.

Luke Lefever
Lefever Plumbing & Heating, Inc.
Elkhart, IN

ALF

I'm a geo guy. Yes, the over all efficiency if you go all the way back to the generating plant, maybe you can say that fuel is more economical. As a consumer I want to buy BTUs as cheap as possible, geo is hard to beat. The limiting factor is the available water temp will top out at aroung 130 deg. F. If you can do less, the system will be more efficient. Works great for radiant and that's why I am visiting this site to learn radiant.

Perry_3

Don't forget the efficiency loss of transporting oil and gas...

It doesn't get to your house without some substantial losses either...

I do not have the numbers handy; just rest assured - they arn't trivial.

For example, ever wonder how much fuel a tanker that brings crude oil to the US from literally the other side of the world... My bet - at least a million gallons.

How much energy does it take to refine oil.... A LOT...

How much energy to pump it through the pipelines across half of North America... More than a drop or two.

How much to deliver it from the tank farm to the service station or depot, and finally your house....

Perhaps when I get some free time I'll see if I can find some data on that.

Natural gas does not flow by itself down pipelines either. There are huge compressor stations along the way... Natural gas powered or course...

Some people never consider the losses of all the systems...

Perry

Dave_4

The big picture

Well, I like to think that I take all of the embodied energy costs into account when I decide on building design approaches, and it just reinforces the basic fundamental goal of increasing efficiency at the terminal end user to pay huge dividends in the source energy use. The cheapest new source of energy is conservation at the terminal end.

Liberal Lenny

So what about payback

I have a family place on MV so I'm familiar with the electric rates currently it's about 20 cents per kwh, my oil bill is about 2.75 a gallon, like I said I'm an oil guy so after reading the article I question the validity of saving 25,000 in five years. I mean if they had installed say a Buderus wall mount, instead of the geo system how long would it take to payback, probably the technology will advance before the payback. Deep thoughts.

Perry_3

Payback - at end of transportation system

In the end - all any of us can really compare is the delivered price of energy to our house.

We can't have much affect on the overall system efficiencies that deliver that energy to us - unless we are willing to move to a location where we can count on virtually point of use service.

So how much will your combined electric bill, gas bill, or oil bill go down if you invest $$$$$ into a system; with a key on how much will it go down compared to the other options:

What are the side benifits of the options in future home changes and environmental awareness.

It is not all black and white - just the numbers in many cases.

Option 1: Crown cast iron Replacement boiler that is installed in same spot using existing chimney with DHW @ $8000

Option 2: Vitodens 200 Replacement boiler with DHW at $16,500 relocated across the basement that allows tearout of existing chimney in the future.

Option 3: Tearout of hot water system and installation of forced air because new furnaces are about $1500 each (which is what the contractor really wanted to do - oh there would be a couple thousand for ducting work).

Option 4: Geothermal... only it could not get me 140 F water for really cold weather (which is what I studied for years and wanted to install). Probably in the $12,000 - $15,000 range.


Which option is worth it? Is it just a simple payback or not - and over how many years.

Perry