But the problem never was in the technology. Wind energy has been around for a long time, and it turns out that it has the potential to provide a lot more of our energy than we though. Almost every continent on the planet, has enough wind to supply all of its needs with the use of HVDC long distance tranmsission lines. The problem is that wind is not there when you need it. However, it turns out that if you connect a lot wind farms a long distance apart with these same transmission lines you can not only supply electricity to low wind areas, you improve reliablity a lot - to around 80% or more. Better the times with low wind drop to very short periods, meaning you can increase reliability to 95% with a moderate amount of storage:
I wrote more extensively about this on the Gristmill blog.
similarly we can produce solar power in the desert much less expensively that photovoltaics by using concentrating mirrors to drive heat engines. Reliability is not so great as with wind, due to that pesky detail called "night". But storage is much cheaper than with wind because you can store heat more cheaply than electricity. The gross cost is somewhat higher than with wind, though differences in storage costs bring them closer: but you can use waste heat from solar thermal plants to desalinate water or drive air conditioners, giving them a reasonable net cost.
I did a very brief post about this on Gristmill as well http://gristmill.grist.org/story/2007/1/14/18543/1388
These are just two examples: but wind and solar themal only combined could provide the vast majority of our electricity in a carbon free form. There are other means to provide other forms of energy besides electricty.
The point is we've know for quite some time how replace all our current energy needs with low carbon sources, at higher but not outrageous costs compared to fossil fuels. We've also know for some time how to use that energy more efficienctly at a cost less than that of fossil fuels. That means total cost, more expensive sources used more efficiently would come out to about the same price we pay for energy now.
And what that tells us is that the problem is not a technical one that a political one. If we have the technical solutions to global warming, have for decades, and their total cost is around the same as fossil fules that is pretty good evidence that the barriers to solving it are political not technical.
an