Simple question with broad impacts. When will our planets fossil fuel resources be depleted.
As a framework for this poll lets assume the following:
Fossil Fuel primarily represents all forms of crude oil used in the making of transportation fuels on a mass scale. I am not any form of an expert so maybe coal and other resources can be used but lets not muddy the waters here. 
I answered < 50 but that’s only w/r/t oil, and possibly natural gas depending on how heavily we use it. We have that flexibility with regards to gas, but not coal, because while we have a crapload of it, it’s dirtier. So while I think our oil will only last for 50 or so years based on current consumption patterns, our coal will likely last longer.
I answered < 25, but I think it will be the high end of 25. That’s for oil (crude + condensate), not counting natural gas.
This guess is based on continued world population growth, continued increase of oil demand in China + India in the next few years, and depletion of conventional oil in Saudi Arabia, northern Europe, the US and elsewhere. While the depletion of conventional oil can to some extent be mitigated by extracting non-conventional oil (tight oil), tight oil wells have steep decline rates that necessitate the constant drilling of new wells to maintain extraction rates. So the situation doesn’t look good.
Of course, it depends what you mean by depleted…in 25 years’ time there will still be some oil left. But I suspect that it will be expensive to extract, and we’ll be living in a time of scarce, expensive oil instead of abundant, cheap oil. In other words, I would predict that we’ll be on the “decline” side of the world oil production curve. (Right now it seems that the rate of production has approximately plateaued.)
What that will do to our economy I don’t like to think about.
Never. It will simply get more and more expensive, to the point where alternative fuels become competitive.
I have to agree with Crafter. There is so much oil and coal and gas out there that’s just not “economical” to tap at today’s prices. Every time energy costs more, more of that fossil fuel becomes available. Eventually renewables will be cheaper.
I may have misread the OP, I assumed it said “assume there will be no alternative fuels used for transportation” but upon rereading I do not see that. There will be a degree of substitution by the end of 50 years, which will decrease the rate of depletion. That said, if there are million of barrels left, if they cost $1000 a barrel inflation adjusted, they will count as depleted for almost all purposes.
That is an answer I suspected would come up (and I agree with)… I tried to mitigate it with the “functionally” and “mass scale” qualifiers.
I suspect that 500 years from now Oil may still “exist” but if it is priced like diamonds if will cease to be functional.
My company does business with Big Oil, and as a consequence we have corporate presence in the big oil markets. I travel to Houston fairly regularly. One one such trip, I was hoisting a couple beers with an exec from one of the Big Oil companies and asked him if there was any truth to the idea that we were going to run out of oil some day. He said “No. Never. There’s so much oil that we haven’t even begun to scratch the surface of what is availaible”, or something along those lines.
True or not, it was an interesting response, and an interesting conversation.
This.
+1
This is obviously the best answer, however I chose <100 years because I think we will still affordably be using fossil fuels at least till then. We can argue on the definition of affordability, but nothing packs as much cheap energy per unit of measure than oil; and if it did we would have converted long ago.
What would you call it when it reaches the point where it’s impractical to use for fuel/energy put still practical for making plastics and whatnot?
I voted >100 years. The case for ‘never’ is solid, but I think there is a point where fossil fuels stop being widely used. ‘Depleted’ is a strong word.
Anyway, stories about shale oil are in all the magazines these days. Apparently there are 100bn barrels of recoverable oil, and scads of natural gas, in the Bakken formation around North Dakota. Venezuela actually has more oil than Saudi Arabia, if you don’t mind steaming that much asphalt out of the earth. There are huge shale deposits scattered all over the planet. I bet we’ll drill it for a long, long time.
That seems unlikely; I don’t think we be in all the hard-to-reach, hard-to-extract oil fields (like, for example, the oil sands of Alberta and Saskatchewan that are making so very much money these days) if all the low-hanging fruit was still available.
I think we’re still asking the wrong question here; the oil will take a very long time to technically run out, but the easy to get at stuff definitely will, and I think that won’t be too far in the future.
The OP asked about fossil fuels and that includes coal of which there is at least a 500 year supply. Probably more like 1000. But that’s not “never”. So I didn’t vote. I expect oil to be effectively depleted within 100 years though. I am not sure about gas.
On the other hand, if sea levels rise, say 50 feet, there may be a political problem maintaining the current level of consumption. Still, they did cut down the last tree on Easter Island.
There is enough coal, land based natural gas and permafrost methane to last a couple hundred years.
However technology should advance to the point where it isn’t cost effective to use fossil fuels long before that. The energy equivalent of a gallon of gasoline costs about $0.80, so when electric cars advance the incentive to use FF will go down.
Ideally. Wind is cost competitive with coal in ideal situations with current tech, and solar is getting close in ideal situations (assuming a 20-25 year lifespan of the panels).
The problem is that the ‘never’ answer is followed up with ‘peak oil is a lie!’ We could still (and probably will) be using oil 100 years after peak production, even if it is only 1/10th today’s consumption.
And I understood the question to be essentially asking when that would happen.
I think it’s reasonable to expect that, within 25 years, oil will be expensive enough that ordinary people will not be able to drive personal gasoline-fueled vehicles.
Again, this seems to be confusing functional depletion with absolute depletion. If oil consumption is economically forced down 90%, that is functional depletion for most people and purposes.
We have about 8 years left. It’s been that way since the mid 1980’s.