Green energy technologies like wind, solar and biomass presently constitute only 3.6% of fuel used to generate electricity in the U.S.   Energy expert Vaclav Smil calculates that achieving Al Gore's renewable energy goal in a decade would incur building costs and write-downs on the order of $4 trillion, note Jerry Taylor and Peter Van Doren at Forbes. 

Is that a lot?  Not spread over 10 years.  That is only 25% of what the U.S. economy lost in 2008-2009 so anyone claiming this investment would be devastating has to note America did not collapse when 4X that much value disappeared completely, so shifting it to something else would certainly have been inefficient, as government always is, but nowhere near as devastating as what happened anyway.     

No one even knows what the Department of Labor in the federal government does but 50% of the cost of implementing renewable energy would be achieved just wiping that thing out.  The Treasury Department costs 2X as much per year as we'd need, though that includes interest on the debt we incur to subsidize a Department of Education which gets $100 billion per year, even though education is supposedly done at the local level and not the federal.

And the military?    I am not knocking the value of helping people oppressed by mass-murdering dictators, I am instead heartened that Democrats have come around to seeing the benefits of using American military might to aid democracy in places like Iraq Libya, but Iraq and Afghanistan alone have surpassed a billion dollars in costs in 8 years.   And windmills would certainly still be here whereas bullets and bombs are gone.

Otherwise, Mssrs. Taylor and Van Doren make fine points, namely that the recurring cost of old, tired renewable energy schemes would be horrifically expensive.  Wind power is 80% more expensive than current technology without factoring in all of the new transmission infrastructure that would be needed.  Progressives seem to only believe in the miracle of capitalism when they are talking about subsidizing something to get it going - costs will come down when windmills get popular because American business is awesome - but otherwise they hate business so the belief that subsidizing something magically leads to profitability is just that; hocus-pocus.  The instances where more government led to more efficiency are still sitting at zero.

What do they mean by old and tired renewable energy schemes?  They rightly note that wind energy has been tried since the agricultural revolution in Europe - the 13th century.  Today, it is slightly more efficient but not by much and due to the remote locations it requires it would mean waiting for battery technology to improve in order to really be a replacement for fossil fuels.    

And environmentalists should note that the last fad in future clean energy - nuclear - is terrifically unprofitable and a concern to even Europeans, who have long bragged how they have cut CO2 by using more nuclear power, but now nuclear power has protests in Europe because of recent events in Japan.

Not everything needs to be profitable, of course.    The American government subsidizes food because it is a strategic resource and we cannot afford to have it outsourced.    Science is also heavily subsidized.   But we have subsidized wind and solar power for decades and no magical boost in efficiency has occurred and to increase it would mean we will soon run up against limits Europeans have run up against in what the government can subsidize and tax for, and privatizing again is a tough sell once people are used to 'someone else' having to pay.   That someone else is still all of us.

Any economic of political free market commentator could have written what I just wrote, and perhaps a lot better, so what is the solution?    I don't think capitalism is out of it just yet and science has a lot of options in hydrogen and other areas that need some technology but are promising.  For as much as conspiratorial progressives want to believe that current industry is squashing green technology, it never holds up.    Big Horse And Buggy was not able to suppress Ford Motor Company.    Google was very late to the search engine party but Lycos and AltaVista could do nothing about it.

Instead, progressives (and conservatives and liberals) should be more suspicious of green tech that industry is endorsing - I am talking to you, CFL bulbs and ethanol - because it is profitable due to it being paid for by taxpayers.

If we have to bet on government or the private sector, bet on the private sector - and necessity.   The green efforts of the 13th century failed but society marched on.  The government did not invent the heavy plow that made Europe a juggernaut for the rest of the millennium, private industry did.   Let's just hope the Black Plague and fewer people to work the fields are not the Mother of Invention this time.