For solar power, clouds are more of a problem in some areas than in others, but night-time darkness is a problem pretty much everywhere.

It almost goes without saying - but one does wonder - that heat and light come in pretty handy at night.

Much like wind power, solar power will remain a bit player until we have much better batteries. Beyond that, big solar power arrays require large tracts of land in sunny areas. As always, there are hidden costs lost in all the gee whiz enthusiasm over small reductions in panel prices.

We have lots of coal. Compared to the rest of the world's big coal burners, U.S. coal-fired power plants are extremely clean-burning and reasonably cost-effective.

We should not be punishing ourselves because China, India, and Russia have dirty coal-fired power plants, and ambitious plans to build more. Let us shake off the undeserved green cloak of guilt and let the blame fall where it belongs, on those nations responsible for pollution, nations which, as it turns out, just happen to be fierce economic rivals.

And in case anyone is wondering, I have absolutely no connection to or financial stake in any coal, mining, or mining equipment concerns.

All I have is common sense and concern for my nation.

S