WN: But there's got to be good things about coal.

Carl: It's cheap.

But look -- the price of the mineral itself is irrelevant. Nobody wants coal, after all, they want electricity services: warm showers and cold beer, as the man put it. If it was only fuel price that mattered, then solar would win every time, since however cheap coal may be, sunlight is free.

The relevant comparison is this: the cost of end-use electricity services delivered by coal-fired power plants vs. the cost of end-use electricity services delivered by some combination of renewables and efficiency. That's the only cost comparison that matters.

The fuel cost is only a tiny part of that comparison. You also have the capital costs to build plants in compliance with all relevant regulations, the operation and maintenance costs of running them, the transmission and distribution costs of carrying electricity over wires, and -- if you really want to be a hippie -- the cost of the externalities created along the way.

If you make the relevant comparison in the U.S., coal is not cheap. Even without CO2 regulations or other externalities priced in, just with Clean Air Act compliance, new coal is about as expensive as wind or solar thermal, and far more expensive than the equivalent negawatts of efficiency. Include a price on carbon or other externalities and the gap widens.

Since India and China have fewer regulations on coal pollution than the U.S. does, and no regulations on CO2, you might still get a lower number for coal over there, if you exclude externalities. But if you include them ... well, here's a tidbit from a World Bank report on China:

Health costs related to air pollution total $68 billion a year, nearly 4 percent of the country's economic output, the report said. And acid rain has contaminated a third of the country, Sheng Huaren, a senior Chinese parliamentary official, said last year. It is said to destroy some $4 billion worth of crops every year.

That's to say nothing of polluted rivers and political unrest. Factor them in, or factor in the money China would have to spend to clean up coal, and it's not cheap any more. Once more from the top: coal is cheap only insofar as it is given freedom to be filthy.

Of course it's not easy to replace coal with renewables and efficiency. Markets for the latter are, as Bill Clinton keeps saying, undercapitalized, underinformed, and underorganized, in the U.S. and even more so in India and China. It will be a huge undertaking to scale them up to meet the challenge.

Should we focus on scaling them up instead of spending a sh*tload trying to clean up the world's dirtiest energy source? I think so. Others disagree. But either way, you have to argue for your answer. You can't just assume that "coal is not going away" and thus that we have to live with it. That kind of assumption makes an ass out of you and ... well, mostly you.