Doly wrote:I'll reply to the comments in an aggregated form again:I would venture that your equation for how fast the supply of a resource is coming on line is flawed, and this flaw is correlated with and only specific to a small subset of the actual resource base available for development in the future. It is similar to the "field growth" problem in that if you make the assumption that only what you see is available for development, you massively UNDERestimate how much resource will be converted into reserves and available for use in the future. Laherrere's estimates are very much a reserve estimate rather than a resource estimate, and would lead any model directly into this particular trap. The original modelers in Limits to Growth stumbled into this issue as well, if I recall correctly.
Actually, that isn't an issue in my model or in the Limits to Growth model. One thing that is easy to test is what happens assuming that there are more fossil fuels available. I said before that I tested for this and you get something similar happening, only a bit later. In the original Limits to Growth model the same kind of test was done by duplicating the amount of nonrenewable resources, and exactly the same thing happens.
Actually, I would say there is an issue. For example, I applied your equation to the basic numbers Hubbert provided in his 1956 paper "Nuclear Energy and the Fossil Fuels", in particular, Fig 21 for starters. Your equation, correct me if I'm wrong, is Production Increase = 0.2 *( Fossil Fuel Percent Remaining - 0.5 ) * Current Production.
Applied to Hubberts high estimate in 1956, that solves as approximately
Prod Increase = 0.2 ( (1-(52.4/200) - 0.5 ) * 2.5 = 0.119 , or, 4.7% increase in that particular year. According to the EIA, that particular year was a 2.6% increase, and the AVERAGE from that point in time to peak production in the US was 2.4%.
But lets not forget, Hubbert was using undiscovered resources in his number...the Laherrere numbers you use equate more to reserves rather than resources.
Again using Hubberts Fig 21 numbers and reserves instead of Hubberts resource numbers:
0.2*(( 1 - ( 52.4 / 82.4 ) - 0.5 ) * 2.5BBO/Yr = -0.07BBO/Yr, a decrease in production of approx 3%.
This is exactly what I said, that a low estimate of the resource base will cause your equation to come unglued, when we know from this particular example that no such profile emerged for another 15 years, and your equation has already called peak based solely on low resource estimates.
How does this equation work in a known decline regime? Using EIA data from 1985 to 1990 and your equation, again on reserve numbers rather than an actual resource base ( something Kawata and Fujita did account for ) it solves as:
0.2*(1- (145/171 ) - 0.5 ) * 3.16BBO/Yr = -0.21 BBO/Yr or 6.6% drop. Actual EIA in that year says it dropped 3.2% and the 5 year running average was approx. 3.1%
So...in one of the few environments where Hubberts peak concepts have actually been reasonable, your equation calls peak and decline early on the upside solely because of a pessimistic resource base estimate, at least in this example, and on the downside overestimates the drop by 2X.
This is why I said there was a problem, here is a systemic flaw which in this example fails in a unidirectional manner, particularly when used in conjunction with large underestimates of resources, which Laherrere certainly uses.
Did you test this equation in any systematic way against a full range of production increases, peaks and production decreases to make certain it mimicked something, somewhere, sometime? Copper, whale oil, coal, steel, wood, uranium?
Your equation is nearly guaranteed to force transition of some sort earlier than it should if you stick to reserves instead of resources, at least in oil and gas estimates. And if this equation doesn't work in about the only place where Hubberts prediction has worked out reasonably well, how much confidence can you have in it mimicking correctly something he missed badly, such as natural gas production in the US, oil at the global level?
With different and more reasonable non renewable resource estimates in the model, would you be willing to bet that "final decline being more moderate" could easily turn into "no decline for the foreseeable future"?
Actually, I'd be happy to bet the opposite. Increasing the estimate of nonrenewable energy sources is not actually improving things in the long term, it tends to make things worse because it increases climate change and makes the transition to renewables harder.
So you equate climate change to more difficulty in transitioning to renewables...because of EROEI? The wind blowing harder because of more energy in the atmosphere makes electricity from wind power more difficult? I don't understand the link here I guess. You don't take climate change into account to drop your per capita heating, but the model does take into account a windier planet...blowing over windmills instead of spinning them harder?
Dolly wrote:Also, once you open up the non renewable resource base a little bit, you'll allow more CO2 output which might provide another 2 or 3C temperature increase, +6C has got to cause less heating needs somewhere.
According to the book "Six degrees", if we reach that point, the lowering of our heating needs won't be the most pressing of our concerns.
Stopping another Azolla event from crashing our planet back into another Ice Age would definitely take precedence on the list of concerns to humanity, I certainly understand that one!
Dolly wrote:One of the reasons I used World3 was because it's well known, so I hope that there will be many more people that are familiar with at least parts of the model and can detect any major flaws.
You've got me interested in this World3 thing now, particularly since Shanny mentioned its open source, although I find debugging a programmers logic or code distasteful.