by gego » Fri 22 Dec 2006, 13:19:54
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Assuming that this graph is correct (no insult intended), that is one scary looking green line.
Sorry, but no warranty comes with my machinations.
The possible flaws: The EROEI (halving every 20 years since 1930) numbers provided by others may be inaccurate; the EROEI rate of decline may not continue at 3.5% (could be worse or better, but a trend in motion should not be ignored); the 2010 peak oil date is an assumption and could be earlier or later; the rate of decline in production after 2010 could be different than the 3.5% assumed (I have read estimates of 8% also).
I am comfortable that I did the math correctly in converting the EROEI ratios (the blue line) to % of net oil available out of gross production (the red line) for each of the declining ratios. The little list of ratios and corresponding % is on page 3 of this thread. You can check this out yourself by some fairly simple calculations. For example, the table shows at an EROEI of 3.125 a net 68%. On 1,000,000 barrels 68% is 680,000 remaining. That means 320,000 barrels were used in acquiring the 1,000,000 barrels. Since the EROEI is 3.125:1 multiply 3.125 X 320,000 = 1,000,000 barrels, proof that the 68% is the correct % for a 3.125:1 EROEI.
For the green line; If the decline rate is 3.5%, this means production falls by 50% every 20 years so the progression of lost production is 100%, 50%, 25%, 12.5% etc. I took the table of %'s on page 3 of this thread and multiplied by this progression; 100% X 84% for 2010 (since 2010 is the assumed peak production date), 50% X 68% for 2030, and 25% X 36% for 2050. This may seem a little contorted, but I did it that way to get it on the graph by keeping everything in percentages. The red line is what would remain out of any theoretical production level after cost of producing. Since we assume that 2010 is peak production, we can then use this as a reference point, hence the green line becomes the % of 2010 gross production that is left at each future date taking into account declining gross production and increasing production cost (falling EROEI). I may be having difficulty explaining the logic, but I do think it is sound. One thing that bolsters my confidence is that the three lines on the graph meet at 1:1 EROEI in 2060.
I tested using different rates of decline in gross production and the slope of the green line changes, but it always meets the red line where EROEI falls to 1:1.
If you are shocked by the slope of the green line as I presented it, consider what it would look like using a depletion rate of 7% instead of 3.5% for post peak production. Instead of falling to 34% for 2030, the line falls to 17% at that date, but is still reaches zero at 2060, so it flattens later. No matter what rate of depletion you assume post peak, you always will arrive at the destination of zero, controlled by EROEI. If you assume gross production stays constant after 2010 the green line matches the red line, if you assume production increases after 2010 the green line is higher than the red line, but it still falls to meet it in 2060; all roads lead to Rome.
This is why Gazzatrone's thread is so important; the issue is not peak oil; it is falling EROEI. The only thing peak oil means is how fast we get to hell; whether we go directly there by 2030 at anywhere around 3.5% or above depletion rate post peak, or we play in the sandbox for a decade or so more before we drop off a relatively higher cliff to go to zero in 2060.
The discussion might better come from oil insiders who have a better understanding of the present and future overall cost structure of oil production, because the better we understand EROEI, the better we can predict our future.