Nobody, least of all power utilities, has ever said that you have to have 100% conventional power as backup for renewables. In fact, most utilities believe that you can get by with about 20% renewables without having to maintain a lot of idle conventional capacity. They can do this using the excess production capacity they already have for plants going down, peak demand periods, etc. Beyond that, you have to start paying for keeping conventional power plants idle as backup. So the real argument isn't that you can't run your economy on 100% renewables at least part of the time, but at what cost.
Mr. Neider's article points out that Germany is around 14% renewables. In fact, 29 US states such as California (33% by 2020) and Colorado (30% by 2020) are currently under state-imposed mandates to provide a certain minimum of renewables. Xcel even believes that they are ahead of schedule in Colorado (see
http://www.denverpost.com/business/ci_18061499 ).
With current technology, providing renewable power at these levels will require maintaining a lot of idle conventional power as backup. This means added expense, which will be charged to customers. On top of that, new transmission lines must be run to wind and PV sites. And there's the simple fact that renewables still cost more per KWH than natural gas. The current Federal subsidy for wind, around 2.2 cents per KWH, is about what it costs to produce a KWH with natural gas (this doesn't include transmission and other overhead). It's so bad that in 2010, states with renewable mandates have electric costs that are 32% higher than non-renewable states (see the Manhattan Institute study referenced below).
In Colorado, Xcel lets customers choose to go on 100% wind if they want. The cost? In 2010, it was 2.16 cents per KWH -- ABOVE the full retail rate (
http://www.xcelenergy.com/Save_Money_&_Energy/For_Your_Home/Windsource/Windsource_for_Residences_-_CO_-_Pricing_Terms_and_Conditions ). Of course, the full retail rate in Colorado already includes the price of meeting the 2020 renewable mandate.
Mr. Neider optimistically says that somehow we will figure out grid optimization and storage issues. But while the power industry is hard at work on these issues, they still have no satisfactory answers. We still have no cheap way to store intermittent power from renewables, for example. Because electric generation is so critical to our economy, it would be folly to bet our future on technologies that have yet to invented.
The study by the Manhattan Institute provides details (
http://www.manhattan-institute.org/html/eper_10.htm ). I should point out that while they compare renewables to coal, the country is moving to natural gas which is now even cheaper than coal.
