Cheap power under our feet

[Aurora]

The Independent - 22/07/12

UK borrows Iceland's geothermal techniques to tap the heat at the centre of the Earth to solve our energy woes.

Article continues ...

[adam2]

This shows some promise, but as usuall is being overhyped.
Heat from geothermal sources is by no means free, drlling the wells is an expensive business, as is installing miles of district heating mains.
Water from deep underground contains various minerals and metal salts and is now considered to be toxic, requiring either proper disposal or pumping back down another well.

In most places the hot water is not hot enough for electricity generation, but is useful for heating.

[kenneal - lagger]

Let's hope that they insulate the houses first to make the whole system more efficient and smaller. It's again a technological fix that might not be resilient in the long term. It's also not likely to be applicable to all towns or to rural areas where the pipe runs would be too long.

[adam2]

If houses were properly insulated, the heating demand would be reduced to the point where district heating from geothermal sources is unlikely to be worthwhile.
The capital costs of supplying 12KW of heat per dwelling are almost the same as the capital costs of supplying 3KW per dwelling.

A larger demand means larger pipes, but the pipes themselves are very cheap. The costs are in planning/nimbyfests, road excavation and making good, and in joints and connections. The costs of burying 300mm pipe are about the same as for 100mm pipe.

Geothermal may have a better future when there is substantial domestic hot water demand, hotels and hospitals for example. If the hotel or hospital do the vast volumes of laundry on the premises (or send it to a laundry contractor that is nearby and connected to the geothermal hot water) then the idea is even more viable.


The space heating demand for offices, department stores and the like is suprisingly small, and falling year on year.
Cooling is the big energy demand, and geothermal is not very suitable for this.

[kenneal - lagger]

In the Woking and Southampton district heating schemes they use the office cooling load as a source of heat for domestic hot water supply during the summer.

I wouldn't want to rely for all my personal heating on a district heating scheme, especially one relying on geothermal heating: not resilient enough for my liking.