McKinsey& Co. published a really interesting, if geeky, report today onwhat it will cost to curb greenhouse gases in the U.S. It's dense andcomplicated and 83 pages long, and I have to be honest and say Ihaven't had time to read it all carefully yet. But I have written aboutit! That's how Internet journalism works.

My first take on the report in today's CNNmoney.com columnis that it offers encouraging news - not the least of which is thatroughly 40% of the carbon reductions needed to cut GHG back by 35 to50% will pay for themselves, over time. This is a complicated way ofsaying that there is an enormous amount of energy waste in the U.S.economy.

Squeezingout the waste won't be easy. Adam Smith nothwithstanding, markets alonedon't seem able to do it - if they worked as they should, most lightbulbs in America would be a CFL bulbs because they are cheaper, interms of their lifecycle costs, than old - fashioned incandescentbulbs. But they cost more upfront and so many people shy away from them.

Likewise,we don't think much about the lifecycle energy costs of the homes webuy or the computers, plasma TVs, VCRs, DVRs, iPods and cell phonecharges that stay plugged in (and draw power) round the clock.

Inany case, if the economy can find a way to realize big savings fromefficiency, it should be able to absorb the higher costs, at least inthe near term, of renewable energy, clean coal and nuclear power, whichare among the other options analyzed in the report.

Anotherencouraging thing about the report is that it assumes no big changes inconsumer behavior. If we can get people to drive smaller cars, live insmaller homes, buy less stuff and recycle more - none of which, Iunderstand, will be easy - then the projected costs of GHG reductionswill be even less.