Hello Gerrit,

On Sunday July 01 2018 08:20, you wrote to me:

 MvdV>> Strictly speaking geothermal energy does not qualify as
 MvdV>> renewable. Half of it is the result of the cooling down of the
 MvdV>> fireball that the earth once was and the other half is caused
[..]
Geologists speak of "fossil heat".

 GK> The definitions are different, though:
 GK> 
 GK> ---
 GK> Renewable energy is energy that is collected from renewable resources,
 GK> which are naturally replenished on a human timescale, such as
 GK> sunlight, wind, rain, tides, waves, and geothermal heat.
 GK> ---

Indeed, by that definition it is renewable. It is not uncommon that definitions
differ depending on ambiance...

 GK> The reason for this is the timescale you already mentioned. Otherwise,
 GK> we'd also have to take solar, wind and water energy out, because
 GK> eventually this is all driven by our sun that will stop shining in
 GK> some far future, too, and annot be renewed.

Indeed. On a cosmological timescale, solar energy is not renewable...

 MvdV>> Other than that , I am not at easy that extracting geothermal
 MvdV>> energy on a large scale will not cause some unforseen nasty
 MvdV>> side effects. Such as eartquakes...

 GK> No single method will be the magic cure. We need a combination of
 GK> everything, depending on location, availability etc.

I say closing down the nuclear plants is a mistake. Especially closing down the
research reactors. we loose the expertise than we one day may need...

 GK> Geothermal power appears to work well enough for Icelanders.

Iceland has a totally different geology. Here we have been pumping natural gas
out of the ground for half a century at a rate of 50x10^9 m^3/year. We thought
we could continue to do so for another decade. But now we suddenly have a
serious earthquake problem... :(

No wonder we are a bit uneasy about cooling down the earth at a depth of 2 to 3
km by extracting heat from it. We will not easely cool down the entire planet,
but cooling locally may have some unforseen side effects in the type of geology
that we have here. Some seismic activity HAS already been reported in areas
were geothermal enery is harvested...


Cheers, Michiel

--- GoldED+/W32-MSVC 1.1.5-b20170303