Why aren’t Geothermal heat pumps more common

air-conditioningheatinghvac

Air conditioning and heating are major energy consumers in American buildings – commercial, residential, and industrial. I have been curious for a while as to why it isn't more common to use the practically constant 50-60*F temperature of the earth just a meter below the surface to bootstrap our heating and cooling needs.

More information on Geothermal heat pumps

As I understand it, the "ground loop" is expensive to dig but lasts for decades. And once the system is in place it's 40-70% more efficient than traditional HVAC on a single household basis.

What I'm really wondering is: why don't municipalities provide geothermal ground loops like they do sewage and water pipes? They could and should be laid together. Tapping into the loop would have some monthly service fee but only for maintenance, not for consumption (unlike water usage).

Best Answer

The technology is relatively young, and not as well known to consumers as traditional heating and cooling methods. The upfront costs of a geothermal system are also higher, and there are fewer companies around with the knowledge and tools to install the systems.

In the US most homes are not built by the home owners, they are built by development companies who buy large plots of land and build as many homes as cheaply as they can on them. When they build these homes most of the products they use are "Contractor grade" (meaning cheap), so that the companies can make the maximum profit. Because of this, the builders typically will not choose a geothermal system over a more common HVAC system if the cost of the geothermal system is higher.

As for municipalities controlling a geothermal system, again this comes down to dollars and cents. If you were building a new city from the ground up this might make sense, but to retrofit a system like this would cost billions of dollars.

Hopefully as the "Green" movement marches on, geothermal and other "alternative" power sources will become more popular. And as they become more popular they will become cheaper, and the cheaper they get the more attractive they will look to average home owners and home builders.

Related Solutions

Why don’t programmable thermostats automatically switch between “Cool” and “Heat”

The logic involved is much more complex.

Right now the logic is simple:

if AC Mode and it's too hot, turn on AC, else turn off AC
if Furnace mode and its too cold turn on furnace, else turn off furnace

But the determination of when to switch between heating and cooling modes is much more complex - otherwise the ac would kick on, and it would get too cold, so hte furnace would kick on, making it too hot, and a cycle would begin that would never end.

So the logic must be more like:

if the average ambient temperature has remained below a certain threshhold 
    for a given period of time 
    and the air conditioner hasn't been on in quite a while, change to furnace mode 
but if average ambient temperature has remained ABOVE a certain threshhold
    for a given period of time 
and the furnace hasn't been on in quite a while, change to a/c,

then if we're in furnace mode and it's cold, turn on the furnace, 
but if we're in a/c mode, and it's hot, turn on the a/c.

The circuitry involved is much more complex, so the price is higher and the market share obviously will be smaller.

Wood – Home heating fuel comparison (wood and heat pumps)

You're right, but only because oil is the worst, most expensive way to heat a home. Pretty much anything beats it, except maybe electric resistance in places with high electricity prices. Wood, gas, and heat pump electric will all beat the pants off oil. That said, even 80% efficiency may be optimistic for a modern high efficiency wood stove. But even if that's overstated, as you can see, it's still a pretty good deal.

Additionally, your calculations may even be understating the advantages of a heat pump. 1.4 as the coefficient of performance is very conservative. I'd use 2, especially given how they not have high-efficiency units on the market than can deliver their rated performance at -15f. Some can go as high as 3 or 4 during periods of non-frigid outdoor temperatures and less than peak internal load.

Edit: you said, "Does that calculation make sense? Are heat pumps and wood inserts really that much better than oil? Can I really save 178 dollars a month by going with a 16 SEER heat pump?"

Yes indeed. But again, only because oil is such an awful fuel. Anywhere in the USA, one therm of oil heat is several times four times as expensive as one therm of natural gas heat, simply because of the relatives prices of oil vs natural gas. If you were comparing a wood stove and an electric heap pump to natural gas, it would get a whole lot more complicated--especially in the cases of a 95% efficient gas furnace, or a state with low gas prices or high electric prices.

No matter what you choose, do your wallet and the planet a favor and heat with something other than oil! It's expensive, it's dirty, and (IMHO) it contributes to awful foreign policy. Just Say No!

Edit 2: Some gov't verification of your numbers: http://www.eia.doe.gov/neic/experts/heatcalc.xls

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Related Solutions

Why don’t programmable thermostats automatically switch between “Cool” and “Heat”

Wood – Home heating fuel comparison (wood and heat pumps)

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