Let's connect some dots...

[RandomGuy]

I do believe that we can replace coal with wind and solar. That makes it a bit more than "supplementary".

Here is why:

As mentioned before, the Chinese are building 2 new coal plants per week, and that is likely to continue. This will rapidly drive global demand for coal up, just as their useage of oil has done something similar to oil. This "locks" them into using coal for the lifetime of those plants, approximately 30 years.

Coal, like oil, faces the same depletion problems that oil does. Yes, there is a lot of it, but it is getting increasingly expensive to mine over time for many of the same reasons.

Coal energy is somewhat tied to the price of oil as it is an alternative source of fuel.

Over time, the grandfathered "dirty" coal plants will start obsolescing. The newer plants that must be built as replacements face higher scrubbing requirements in terms of pollution reduction, and this will drive the costs of new coal plants higher comparative to past trends.

Technology will bring the costs of wind/solar down at the same time that coal energy starts getting COMPARATIVELY more expensive. Not only will the tech get better, efficiencies of scale will start to kick in, further driving costs down.

All this will happen whether we do anything about it or not.

Personally, all I am really advocating is that we get a step or two ahead of this.

Yes, it requires an up-front investment that will make prices higher in the short term.

Over the long term that means we get to:

1) divorce ourselves from the price volatility that fossil fuels are prone to, and
2) keep from having to import quite so much of our energy base.

I would sooo much rather our money go to providing jobs in the US than to propping up tinpot jackasses like Chavez, Khadafi, or Amadinidork.

Long term it will mean that we will end up paying MUCH less for energy, as we will be insulated from the worst effects of Peak Oil.

[RandomGuy]

Photocells will become a viable way to supplement small scale needs like a home, but I seriously doubt it will ever be viable for large scale electrical production. There is better technology for this purpose. I forget the name, but it entails concentrating the suns energy with mirrors, then run a steam turbine or other similar method.

You are talking about "power towers" or heliostats. The tech part of what is termed "thermal solar", although even within this term there are a couple of different technologies.

"Concentrating/Concentrate Solar Power" is probably the best term.