I must admit to taking pleasure in monitoring the world of energy. But my typical post is the topsy-turvy world of oil and gas. My Foolish colleague Chris Barker frequently does yeoman's work in deciphering the world of coal for our Foolish community.

While the oil and gas group, from Big Oil companies like ConocoPhillips (NYSE:COP) and BP (NYSE:BP) on down, have all been thumped by dwindling demand (and prices) during the past quarter, most of the coal producers have held up nicely, despite similarly sliding call for their output.

Take Appalachian producer Alpha Natural Resources (NYSE:ANR), for instance. The company reported a 61% jump in its first-quarter earnings to $41 million, or $0.58 per share -- a dime higher than expectations -- compared with $25.5 million, or $0.39, in the same quarter a year ago. All this occurred as revenue actually declined from last year. And there wasn't any real singular magic here: Alpha's Appalachian neighbor International Coal Group (NYSE:ICO) also served up an awfully strong quarter, as did competitor Patriot Coal (NYSE:PCX) last week.

There are a couple of keys to this coal versus oil and gas dichotomy. First and foremost, the coal guys were operating under robust contracts signed last year. Coal prices at Alpha were 25% higher in 2009’s first quarter than a year ago. That, of course, hasn't been the case with the oil and gas operators.

But secondly -- and somewhat amazingly -- Alpha and its coal brethren have been able to cut costs faster than revenues have fallen. The company's costs were $417.3 million in the latest quarter, versus $447.1 million a year ago.

The difficulty is that this set of circumstances can't continue in perpetuity. As Alpha observed, "Most of the key drivers of coal demand remain mired in a slump of historic proportions." And the company also noted that U.S. electricity output has slid by 3.3% through mid-April. Also, with domestic steelmakers like U.S. Steel (NYSE:X) and Nucor (NYSE:NUE) down to less than half of capacity, coal demand is taking another hit. And then we have to account for the growing political considerations likely to affect the group. So we'll have to be diligent about watching that next round of coal contracts.

Nevertheless, this is an amazingly resilient industry. The management of Alpha, for instance, has been extremely adept at staying ahead of the gremlins. For that reason alone, I'd watch the company carefully and, as conditions warrant, perhaps drop a few shares into my portfolio pouch.

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Fool contributor David Lee Smith doesn't own shares in any of the companies in this article. He does, however, encourage your questions or comments. The Motley Fool has a disclosure policy.