The Naked Scientists

The Naked Scientists Forum

Author Topic: Why are we not making more use of Geothermal energy ?  (Read 1452 times)

Offline Grimbo1

  • Jr. Member
  • **
  • Posts: 24
    • View Profile
Why are we not making more use of Geothermal energy ?.
Are the technical problems that difficult?
What are the problems?


 

Offline CliffordK

  • Neilep Level Member
  • ******
  • Posts: 6321
  • Thanked: 3 times
  • Site Moderator
    • View Profile
Re: Why are we not making more use of Geothermal energy ?
« Reply #1 on: 21/01/2014 20:50:15 »
I've wondered a lot about that.  At least for heating. 
Iceland of course has a lot of volcanic activity, but also leads the world in geothermal resource utilization. 

I think to effectively use the geothermal energy, one must have a fairly deep well shaft, say a few thousand feet deep.  Perhaps one should have a pair of holes so that one can pump water down one hole and up the second.  The advantage of a volcanically active region like Iceland is that I assume the holes can be much shallower.  Nonetheless, the geothermal development of a single pair of wells is expensive.

The capital investment is likely quite high, but then the payoff should be good for a very long time.  It may be possible to locally decrease the crust temperature slightly, but that may not be bad either.  There may even be some advantage of pulling up deep minerals.

It may be hard to justify the expense for an individual home, but the University of Oregon has annual energy expenses of about $2.3 million in Natural Gas plus $2.1 Million in Electricity.  So, a few years total energy budget would pay for quite a bit of well drilling and well casing.  It would seem to be worth it for universities, or perhaps even some large buildings that are as big as small cities.

What can be used on an individual basis are water based heat pumps, using the water at about 60 degrees as a energy exchange medium, cooler than the hot summer days, and warmer than the cool winter days.  Some people have also used buried pipes for air circulation and direct summer cooling.
 

Offline David Cooper

  • Neilep Level Member
  • ******
  • Posts: 1505
    • View Profile
Re: Why are we not making more use of Geothermal energy ?
« Reply #2 on: 21/01/2014 22:05:56 »
The cost of drilling is the main barrier, so it's only viable if the hot rock is shallow enough to be worth drilling down to. Southampton (https://www.southampton.gov.uk/s-environment/energy/Geothermal/) is lucky in that regard, but there are only a handful of other sites in Britain where the same could be done without losing money. For power generation it needs to be hot enough for the water to turn to steam, but it's still worth getting to the surface for heating purposes, so lower temperatures are also of use. There's hot rock everywhere if you drill deep enough, but if the drilling costs are too high, you never get paid back on your investment, and that's the problem.
 

Offline Grimbo1

  • Jr. Member
  • **
  • Posts: 24
    • View Profile
Re: Why are we not making more use of Geothermal energy ?
« Reply #3 on: 22/01/2014 09:52:53 »
I see the point about drilling costs but there must be plenty of deep mines that could be used.
Thermal vents on the ocean floor, maybe even volcanos.
All that heat going to waste, it must be better than burning fossil fuels or nuclear power despite the cost. 
 

Offline CliffordK

  • Neilep Level Member
  • ******
  • Posts: 6321
  • Thanked: 3 times
  • Site Moderator
    • View Profile
Re: Why are we not making more use of Geothermal energy ?
« Reply #4 on: 22/01/2014 10:17:18 »
The easiest access for geothermal energy is when the hot water naturally just comes bubbling up to the surface as at Belnap Hot Springs where they have hot spring fed swimming pools.

Since Oregon is part of the "Ring of Fire", one would expect more geothermal exploitation.  As David mentioned, Steam would be nice for power generation, but a lot of energy is used with building heating, which could be supplemented with even more moderate temperatures of geothermal heat (or use it to feed heat pumps). 

Urban vs Rural locations of the high grade sites may be an issue if one is planning on using it for building heat, although it is often good to locate power plants in rural areas.  I'm not sure what the risk of deep wells in active volcano areas, but presumably if one is actually slightly cooling the subsurface area, the risk would be minimal away from volcanoes.

A while ago I suggested using abandoned oil wells for geothermal energy recovery.  One might have issues with urban vs rural location of the wells if one is just recovering low level hot water for use with direct building heating, but I would think there would be some wells that were applicable.  Of course one probably wouldn't get boiling water from an oil well, but warm water would still be nice.
 

The Naked Scientists Forum

Re: Why are we not making more use of Geothermal energy ?
« Reply #4 on: 22/01/2014 10:17:18 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums