> From: email@example.com
> Oh, and usable solar power systems have been a
> decade away since the mid 70s.
Yes, but you have to study both changes in the economic environment and the rate of maturation of technologies.
The Arab-induced oil shortages of the 70s were "artificial". They were turned on/off on the whims of a few individuals. The reason that there haven't been any since then is that in part because the suffering they caused induced the development of alternate sources (Alaska, North Sea, etc.), and substitutions (France going to nuclear, work being done on gas turbines for electricity [gas is abundant]), etc.
But because those sources & substitutions used 20-60 year old technologies and were *existing* industries (oil, nuclear, engine manufacturing) they could be ramped faster than PV could (which was about a 10-year old technology (& a non-industry) in the mid-70s). PV is now a relatively mature technology (we can build cells at close to the theoretical limits of efficiency) and has developed into an industry (all those communication satellites don't run on kerosene...).
So PV technology has moved from the science phase through the engineering phase and into the industrial phase, where you have a production experience learning curve & return-on-investment calculations involving volumes that determine what things will cost when. Competition in the industry helps as well.
So while the predictions may have been premature in the '70s, they are much less so now (there is an equivalent of "Moore's Law" for PV costs, but it isn't as dramatic). On the other hand fusion (cold or hot) are still pretty much in the pre-engineering phase so I'm relatively sure the singularity will be here before I've got a fusion reactor in my house.