I'm not claiming such an alternative exists at the moment, but that doesn't mean we should stop researching renewables and conservation and put all our eggs in the clean coal basket. The nature of innovation is that we try many things before finding something that works. If clean coal really is the best answer, then it will happen.
I too believe that we need to work on a lot of methods. Backing any one horse is insanity. Wind is nice, but not a constant producer. Solar is nice, but also not a constant producer. We don't really do mass energy storage yet. Nuclear is great except for PR and waste (still irks me we spent all that tax money on a permanent solution and then we cannot use it). We need a whole list of sources that provide a secure blanket no matter what goes on.
Conservation will work for the first world, but not the growing economies. They want a first world life and know how we got there.
Also, the US needs to realize there is a large tax implication in switching from a liquid fuel economy for transportation. We need to work out these issues without killing the poor (GPS = big hit bills = poor with transport in large areas of country not serviced by mass transit) or messing up other areas of the economy.
Look at China, coal is their answer because it is cheap and available. We could do more good in the world, if someone created a clean coal process and license / gave it to the Chinese.
We have the luxury of being greener with current technologies, much of the world is not in that position.