by zoidberg » Wed 03 Sep 2008, 22:39:12
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')You are correct. It's called EROEI, energy returned on energy invested. I don't know the exact EROEI of tar sands but i do know you'll end up with a lot less energy extracting oil from tar sands than you do extracting oil from a 'regular' oil field.
EROI is about 1.5-3 depending on various things. It is however trending down as the mining operations have to go farther and farther. Typical resource depletetion story.
Deep sea oil operations have an EROI of about 5.
The first oil fields had an EROI of about 100.
I'm not too sure what the EROI of a Saudi oil field is but I've heard 20-1.
The tar sands will remain profitable in both dollar and energy terms for quite some time, however they will not scale up much farther. It is correct to state they are not a replacement for Arabian light crude. It is not correct to state they are worthless. With Shale gas ramping up rapidly they can provide a substantial liquid fuel output for many years.
What one has to keep in mind is that they allow for a consistent output for long periods of time, without a substantial growth potential. Their EROI wont go below one for decades. This doesnt support a growth based economy, but does support a constant state economy.