Writing for Salon, Joseph Romm says that concentrated solar power (CSP) is the key to solving our energy problems.

One of oldest forms of energy used by humans -- sunlight concentrated by mirrors -- is poised to make an astonishing comeback. I believe it will be the most important form of carbon-free power in the 21st century. That's because it's the only form of clean electricity that can meet all the demanding requirements of this century.

Romm argues that CSP, which uses heat from the sub to move an electricity-generating turbine (as distinct from photovoltaics, which convert sunlight directly into electricity) can produce energy more efficiently coal or oil or even nuclear power. He claims that CSP can provide power at a cost of 10 cents per kilowatt hour or less. Concentrated solar power's big advantage over conventional solar power has to do with storage:

The key attribute of CSP is that it generates primary energy in the form of heat, which can be stored 20 to 100 times more cheaply than electricity -- and with far greater efficiency. Commercial projects have already demonstrated that CSP systems can store energy by heating oil or molten salt, which can retain the heat for hours. Ausra and other companies are working on storing the heat directly with water in the tubes, which would significantly lower cost and avoid the need for heat exchangers.

Romm provides a number of interesting examples of CSP applications throughout history. Before the invention of photovoltaics, CSP was the only real model for generating solar power. He even gives an example of a CSP-powered pumping station that was built and put into operation in Egypt in 1913. It was shut down during WWI, and then never reopened once cheap oil established itself as the dominant energy source.

So it's interesting to see CSP making such a striking comeback. It reminds me of the recent news about production of automobiles running on compressed air - another idea that was experimented with a century or so ago, then pretty much forgotten, and which has now found new life. New technologies and new market conditions provide the opportunity for abandoned and all-but-forgotten ideas to re-emerge. My favorite example of this has to be the idea of building a Charles Babbage-style difference engine at the nano scale -- a model of computing that would have been awkward and clunky to implement using 19th century industrial technology, and which was deserted in favor of 20th century electronics technology, now finds new life with 21st century nanotechnology.