Welcome to European Tribune. It's gone a bit quiet around here these days, but it's still going.
This is a point I tried to make. "One point extra EROI" is quite uninformative, since the difference between 39 and 40 is the difference between a net energy yield of 97.44% and 97.5%, while the difference between 3 and 4 is the difference between a net energy yield of 67% and 75%.

EROI is important when a substantial change in EROI implies a substantial change in Net Energy Yield. We are not at that point yet with most of our status quo systems, but we are approaching that point. Natural Gas is already on the edge of the threshold where difference in EROI starts to become pragmatically imoprtant, according to this Scientific American infographic:

... and coal at a current ERIO of around 18 is under threat of heading that way if climate-change oriented policies fail to keep coal in the ground and we hit peak coal in the coming decade.

And that is an important point. For peak power, solar PV and Natural Gas are coming close in terms of EROI, and solar PV EROI is heading up while Natural Gas EROI is heading down, due to a larger reliance on fracking versus natural gas co-produced from conventional oil production. For nighttime power, coal and windpower are close in terms of EROI, and windpower EROI is rising while coal EROI must inevitably decline.

I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.

by BruceMcF (agila61 at netscape dot net) on Wed Jul 24th, 2013 at 11:59:54 AM EST
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