On Wed, 21 Sep 2005, Wouter van Ooijen wrote:

>> The argument was that, after the higher grade hydrocarbon stores are
>> exhausted, there is no available terrestrial energy source available
>> that produces more energy than it consumes in its production.
>
> If you include sun energy into the equation this statement is an obvious
> truth. If you exclude sun energy it is obviously false, otherwise no
> life would exist on earth.

I will have to ask my pet rock about that.

Seriously, people are a way for nature to increase entropy, from the 
energy point of view. So the 'energy gain' problem's answer will always 
be negative even if we bring in whatever fuel from wherever, because all 
human activities have an efficiency lower than 1.

So as long as nobody tries to build a perpetuum mobile, and losses are 
reasonable, anything goes, from burning camel dung to He3. As to gain, I 
don't think that ever was the case. It all depends on how you set your 
control volume. For example fossil fuel is considered to require less 
energy for extraction than it produces *if* one disregards when it was 
produced and how long it took, but energy quantity is scored by its 
price, and that depends on human factors such as cost of labor, taxes, 
and distances. Economics, and not physics or conservationism drive the 
energy industry.

As long as one stops thinking about 'gain' and starts thinking about 
'maintainable loss' things start to have solutions. Of course each 
foreseable solution has an expiry time associated with it.

Peter
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