Even if you take 9/11 out of the equation, the economics make it difficult.

"We're still not getting the rents of the late 1980's and the economics don't make sense," he said.

"We were pleased to learn that the economics made sense as well."

"The economics just doesn't make sense for these regional theaters."

Sometimes we see a few more get started, but the economics make it difficult to keep them going.

But isn't it the case the economics of blockbusters make no sense?

Now, the economics of this made absolutely no sense.

The question is, 'Can you bring it in at a cost where the economics make sense?'

And, of course, the economics only make sense to people who think that prices for conventional energy will keep rising.

But as the numbers grow, so do the questions about whether the economics of such an approach make sense.