Geothermal heat pumps: why aren't they in much wider use?

[IDemo]

I live in an area that pioneered the type of geothermal heating most people think of when they hear the word: piping hot water from deep wells. I actually enjoyed this type of geothermal heat free at a large apartment complex here in Boise, Idaho several years ago. It is still used to heat many historic homes on Warm Springs avenue, along with the Boise City Hall, Ada County courthouse, the federal building, and many other buildings. Idaho is a very geologically active region, and numerous hot-springs dot the state.

What really interests me now though has nothing to do with the above 160 degree+ sources of water. There is another flavor of geothermal which is accessible by essentially all, regardless of your local geology: Geothermal heating systems, also called ground-source heat pumps. These effectively use a heat pump to both draw and deliver heat energy to the earth, much like a battery. The basic idea: the ground below the frost line, generally four to six feet down, remains at roughly the same temperature year-round, say about 50°. This can be used to the advantage of both heating and cooling systems. Instead of using a regular furnace, which consumes large quantities of natural gas or electricity to bake air and push it through heating ducts, the passive geothermal system draws heat energy from an anti-freeze solution running through a network of buried pipes. Yes, even 'cold' (by human standards) earth and air still contains heat energy.

An added benefit is that a household's hot water requirements can largely be met during summer months with heat drawn from the house. This is referred to as a “desuperheater”.

[LynzM]

1. I think it's coming, especially as heating gets more expensive

I have a friend who is launching a construction business, and is in the process of building his first house with this technology. He's hoping it will catch on around here, and I wouldn't be surprised. New England winters are Expensive.

[Strelnikov_]

13. I Agree. We Are At The Cusp Of The Final Energy Crises

So when we look at systems like geothermal heat pumps, we are prone to wonder why they have not had wider use.

We have to remember that just a few years ago CERA was telling policy makers that North America had extensive natural gas reserves. Considering the price of natural gas (and fuel oil) up to a few years ago, the up front cost of a geothermal system could not be justified from a purely economic standpoint.

[satya]

2. * uses it to cool the pigfarm.

Everyone wants a secure retirement. President Bush can look forward to spending his retirement years in his passive-solar, geothermal-cooled Crawford ranch house that has been called a "paragon of environmental planning." To help today's children achieve a safe retirement, the Bush administration should be adopting energy policies that will create new clean energy jobs for them and help ensure climate security for their Social Security years.

link: http://www.americanprogress.org/site/pp.asp?c=biJRJ8OVF&b=361917

Let them eat cake, says he...

[IDemo]

6. * has had inside info for many years from his brother, Bandar

Along with his uncle Dick. The coming energy crunch won't be kind to those who haven't taken the steps to prepare themselves. Consuming and driving less, to begin with.

This (passive geothermal) strikes me as a relatively easy and inexpensive step, easily achievable without a 'Manhattan Project', that could provide measurable energy-saving results within the next five years, instead of after twenty.

[satya]

10. I agree it's a great idea. My folks use it in their home and we've

considered retrofitting ours. I think we need to start setting up nonprofits/co-ops to do these things; obviously there won't be any leadership on this issue from the BFEE.

[OffWithTheirHeads]

3. It's expensive and very labor intensive

to install compared to more conventional systems. It is hard to justify the payback unless tou plan on syaying in the house for a long time. This may change as conventional fuel sources get ever more expensive but they still burn electricity at a pretty high rate.

[One_Life_To_Give]

14. Any Estimates on additional cost?

What would the cost be compared to say a Gas or oil fired furnace? What about Gas heat with ordinary central air?

[sam sarrha]

4. u have to be in an active geothermal area,

[IDemo]

7. No you don't. Read the OP

This has nothing to do with your local geothermal-hotsprings activity. It involves using the 'temperate zone' four to six feet below the surface as a heat energy source during winter, and as a heat-sink during summer.

[SnoopDog]

5. Geothermal has different meanings....

Geothermal #1 means, yes, using piping hot water from the earth. But this is rare as it is not prevalent all over the USA. Here in Nevada, yes there are geothermal energy but an entire energy system is use to produce energy for parts of a city. This type of energy is not really conducive for individual homes.

Geothermal #2 means that pipes are sunk 100 to 300 feet and latent heat from the earth is used as a preheater for your household energy systems. This would include the hot water heater and furnace heat. I am a firm believer in solar and other forms of renewable energy. I sort of question geothermal in this case. Yes it does preheat the air - that can be between 40-50 degrees and indeed does represent renewable energy. But systems I have looked into costs $16k. I guess I would prefer a PV system that I can gain electricity for the whole house.

my $.02.

[Massacure]

8. # 2 only needs borehooles 100-300 feet deep if you are going verticle.

Horizontal piping is cheaper, but requires more land.

[SnoopDog]

9. Correct..

Should have made that distinction. I somehow feel that a vertical shaft would garner more heat as our earth heats up as we go toward the center. But I stand by my original point that I feel it is more cost effective to utilize PV.

[boise1]

15. This looks like a quicker payoff than photovoltaic to me

http://www.eere.energy.gov/consumer/your_home/space_heating_cooling/index.cfm/mytopic=12640

Even though the installation price of a geothermal system can be several times that of an air-source system of the same heating and cooling capacity, the additional costs are returned to you in energy savings in 5–10 years. System life is estimated at 25 years for the inside components and 50+ years for the ground loop. There are approximately 40,000 geothermal heat pumps installed in the United States each year.
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http://www.motherearthnews.com/Green_Home_Building/2005_June_July/simpler_solar/

The time it will take for your system to pay for itself depends on the amount of sunshine in your area; the cost of the system; local electric rates and future inflation; your state’s metering laws; your system’s type and size; and rebates and tax credits. A good installer should be able to work out all these variables for you on paper. Or once you have a system price quote, you can download the spreadsheets at www.MotherEarthNews.com/downloads/simplesolar to calculate your approximate payback period and return on investment (see Grid-tied Solar Money Management for examples). “Payback” is the number of years it takes for your electricity savings to equal the system’s cost and maintenance.

If you live in an area where net metering is not available, a solar electric system for your home probably won’t pay for itself during your lifetime, unless the declining supply of coal and oil causes unprecedented increases in the cost of electricity. Your money may be better spent on energy-efficient home improvements (see The Size of Your System Relates to Energy Efficiency).

[IDemo]

11. No need for 300' depths. Again, I think the term 'geothermal' may confuse

the concept for many. This does not involve the use of either geothermally heated water or of 'hot zones' within the ground. It is all about using a thermally-neutral section of the subsoil, four to six feet down, to extract heat energy as needed during cold weather, and to sink (lose) heat energy during hot weather.

http://www.popularmechanics.com/home_improvement/home_improvement/1275586.html?page=2&c=y

- "a ground-source heat pump, with its underground piping loop, is able to tap a warmer, more stable heat source. The soil below frost level–4 ft. to 6 ft. deep–stores the sun's energy at a more or less constant level, with temperatures keyed to latitude. Subsoil temperatures range from the low 40s in the North to the low 70s in the South.

For purposes of comparison, we'll use the 55 degree F soil temperature common in much of the Midwest and Central Plains. This area of the country suffers some extreme temperatures, but also has a fair number of mild days, so it's a reasonable choice.

With a ground temperature of 55 degrees F, the system needs to boost the heat a mere 15 degrees to 20 degrees to reach a comfortable indoor temperature. Compare this to the 40 degrees to 60 degrees maximum differential that an air-to-air heat pump may handle, and even greater differentials expected of standard furnaces, and the logic comes into focus pretty quickly. The only influence outside air temperature has on the equation is in the home's ability to retain heat. Houses lose heat faster on colder days, so all systems work harder in cold weather. But while a ground-source heat pump may need to run more often on these days, it doesn't run less efficiently.

The geothermal principle works about as well for air conditioning. Instead of an outdoor compressor laboring against the heat of the day having to use hot air as its heat-shedding medium, a ground-source heat pump operates indoors, using ground temperature as its starting point. The result is a 20% to 40% savings over conventional heat pumps and air conditioners."

[SnoopDog]

12. As per my post - I totally understand the concept.

And thanks for pointing out the 4 to 6 feet vertical system gain.

I truly feel this is advantageous however I would also investigate the PV solution. One proposal I got had a price tag of $16k and felt maybe a $20k PV system you be more cost effective.

I am totally open to all clean energy systems.

[skids]

16. It is a growth industry.

Geoexchange has been building its share of the HVAC market for 20 years, gaining support in both the public and private sectors. Today, it captures about one percent of the United States' $64 billion HVAC market. Market analysts expect that figure to grow to nearly seven percent early in the next century, carried on the demand for efficient, earth-friendly 'space conditioning.'

In the residential HVAC equipment market, there are two major sectors: new construction and residential retrofit. Currently, 66 percent of the activity is in the retrofit area, which includes energy upgrades, replacements, add-ons and remodeled units

In new home construction, reasonable interest rates and favorable demographics are expected to fuel the home building industry for the foreseeable future. The largest increase is expected to be in the 35-64 age range-baby boomers who have higher income and higher standards of living.

Current data supports a scenario of continued growth across all market sectors.
Over the past five years, unit sales nationally have climbed at an average of over 22 percent per year. The 22 percent growth rate represents an increase of over 10,000 units annually.

http://www.geoexchange.org/press/builders.htm
One must ask: How fast it would grow if the companies were big enough to have TV ads and scale up quickly with demand?

[Kolesar]

17. Is such an electrical system cost effective at $0.13/kWh?

Most homes in Ohio use natural gas.

Note: There is a new development in the next town that has geothermal for every house. That makes more sense than trying to do one retrofit at a time.