Geothermal Home Heating
I am curious why we cannot heat our homes with geothermal
energy? Theoretically, couldn't a hole be drilled deep enough for water
to be heated in an insulated pipe for the return trip and heat our homes
like a furnace heats my hot water. What is stopping us from tapping into
this technology? It would seem, once installed, we would have constant
heat for our homes 24-7 forever and that would offset the cost of the
deep drilling and creation of a pumping system to bring up and push down
the hot water. I am just looking for someone to help me get an answer.
"In principle" one could drill a deep hole (How much would that cost
"up front"?). The well and heating system would have to be maintained
against corrosion, the escape of noxious gases such as H2S and SO2 as well
as water at either high or low pH (That would require constant monitoring
and correction.) How would you power the pump that brings the hot water up
and the cold water down (or dispose of the cold water). That cost would
have to be factored into the overall economics of such a heating system.
Suppose you live in an area that requires cooling in the summertime. How
would a cooling system be engineered that could work both as a
heating and cooling system? How would it compare to other "free" sources
of energy like wind or solar power? How would such a system operate in a
densely populated urban area where there are multi-floor apartments?
My "objections" are not meant to belittle your question. Your's is a
valid question and deserves a serious response. But the problem is
technically complicated, and has many other "side" issues in addition to
drilling a deep hole--overall cost compared to existing systems,
environmental side effects, maintenance, and so on.
There was a time, 50 years ago when paying 40 cents a gallon for
gasoline was viewed as a rip-off. Today we are looking $4.00 a gallon in the
face. So what are objections to your suggestion today may evaporate tomorrow
depending upon the cost of "energy".
You CAN heat your home with geothermal energy. How practical it would be
depends on where you live.
Economical geothermal heat requires that the heat reservoir be close to the
surface. Yes, there are hot rocks underground everywhere, but for much of
the US the depth is quite large. In the US, easily accessible geothermal
reservoirs are located in the Western states, Alaska, and Hawaii. The
country of Iceland has ample sources of geothermal heat and much of the
nation's energy is supplied that way.
There are many web sites that describe different ways of extracting heat from
hot underground formations.
Click here to return to the Engineering Archives
Update: June 2012