I concur with the opinion that weaning ourselves off oil, or at least fossil fuels in general, is not going to happen within 15 or even probably 30 years.

One additional factor however is, in my opinion, it has been found recently that we have a whole lot more natural gas in the US than previously thought, due to the fact that we now know how to tap into the "unconventional" sources like the "shales" (Barnett shale, etc)

Probably the stupidest energy strategy is to do nothing, in which case it won't be long before we are paying 4,5, 10 dollars per gallon for gasoline. As was pointed out in the original post on this thread, even with demand dropping in an economic downturn, supply will be dropping even faster based on the very rapid dropoff in oil production of existing fields that all analyses have been projecting.

A somewhat better strategy is if we start switching over our ground transportation system to natural gas. If we can do those as hybrids, all the better.

Once we did that we would probably be able to continue, as J Kunstler likes to put it, "happy motoring", in my opinion for 2-3 more decades. I agree with a lot of his assessment of what we may be facing in the future, but I think his time frame is way shorter than the way things are actually going to play out, particularly due to all the natural gas supplies that we now have in the US.

What about other countries? Not sure. They may be able to do a similar scenario relying heavily on LNG from places like Qatar.

Anyway, my view is the peak fossil fuel crisis is certainly coming, but it may very well be posponed a couple decades on account of natural gas.

Ironically, we may have a severe transportation fuel crisis in the next 10 years or so, not because of the time lag to switch over to renewables, but because of the time lag to switch over to natural gas.

What about electric cars? Well, if better batteries are perfected fast enough, maybe we can switch over to those in nearly the same time frame as a switchover to natural gas vehicles.

But functionally a natural gas vehicle will be very similar to a gasoline one, a little crummier because of the large tank, but otherwise about the same. Getting the same functionality out of a pure EV I think may still be quite a ways off.

Of course, if we didn't have fossil fuel vehicles, we would certainly settle for whatever we could get, people would certainly drive something along the lines of a battery powered golf cart than not have a personal vehicle at all. But, so long as there are fossil fuel vehicles to be had that aren't prohibitively expensive to run, which I believe will be the case for natural gas cars for several decades, people are liable to prefer those.

Unfortunately, that means we may wind up with a long period of complacency driving our natural gas cars instead of gasoline cars.

That era of course will eventually end as well. If society is smart enough to continue to improve EVs during that time, then perhaps they will be able to make a fairly painless switchover.

In terms of switching over to renewable energy in general (not just with regard to vehicles), I believe we are looking at about a 100 year transition.

When I talk to lay people who are renewables buffs they think I am nuts to believe it will take that long. However, when you look at the writings by experts on renewables, they talk in terms of goals like 20% of our electricity from renewables by 2020. If we just look at electricity, one would figure, well we ought to be able to do the remaining 80% a lot faster than just at a linear 1% more per year, which is the rate we would be going at if my 100 year hypothesis proved to be correct.

However, I think that there are some important challenges that most renewables advocates, especially those without science or engineering background, fail to recognize.

If to have a renewable electric grid all we had to do was replace all our existing power plants with wind and solar generators, then the switchover indeed could be quite fast, because economy of scale would allow us to ramp up our renewables sources at an exponential, not linear rate.

However, once we reach a certain percentage of renewables, the intermittency problem starts becoming a real thorny one. I saw a discussion on TV from some conference in Seattle recently and one utility guy seemed to be contending that the way you deal with intermittency is you simply change the price on a minute by minute basis. When the wind is blowing you buy your electricity dirt cheap, when the wind is not blowing and the sun is not shining then you pay through the nose.

I guess that's one approach, although not one that is likely to be too popular unless there is no alternative, the alternatives being as far as I can ascertain either 1). huge energy storage facilities or 2). a massive highly-efficient global power transmission system (I believe Al Gore is a proponent of the latter).

The technology does not yet exist for either of those. The second of the two not only has technological challenges; geopolitical considerations might also be a show stopper for that one.

Then of course the other big problem with transitioning to renewables is that not all end-uses of energy can run on electricity. The most commonly cited example, of course, is aircraft. If we're lucky, we may be able to produce enough biofuels for those things that absolutely need hydrocarbons.

Anyway, a renewables world is a long ways off. But for those who think we can get there a lot faster than I do, I think we can all agree on one point. We need to develop them as aggressively and quickly as possible.