renewable energy (was: nuclear power: abundant? and cheap?)

["John S. Denker" <jsd@MONMOUTH.COM>]

AFAICT my previous remarks about what it would take
to replace nuclear electric-power generation (or all
electric-power generation) by photoelectrics remain valid.
My numbers are not contradicted by the numbers in Rick
Tarara's reply, even though the numbers are radically
different.  His numbers are the answer to a different
question.

And Rick's question is certainly the more-important
question.  Even if you think getting rid of nuclear
reactors is super-important, they are only 20% of
the US electricity industry, which is only 20% of US
energy budget.  So there would remain a big problem:
93% of the US energy comes from nonrenewable sources.
Nonrenewable includes fission;  renewable is about
half hydro and half biomass, plus negligible amounts
of wind, geothermal, et cetera.
http://www.eren.doe.gov/consumerinfo/refbriefs/da8.html

Looking toward the future, it seems to my non-expert eyes
that the decision tree doesn't leave much wiggle room:

        Start
        |     \
        |      \
        |       \
        |        \
        |         nuclear
        |         |     \
        |         |      \
        |         |     fusion:  unproven
        |         |     possibly unworkable
        |         |     (End)
        |         |
        |         fission
        |         |      \
        |         |       \
        |         |      breeders:
        |         |      serious safety &
        |         |      proliferation problems
        |         |      (End??)
        |         |
        |         non-breeders:
        |         exhaustion
        |         (End)
        |
        non-nuclear
        |       \
        |        \
        |         \
        |          \
        |           non-renewable
        |           |           \
        |           |            \
        |           |             \
        |           |              \
        |           greenhouse      no greenhouse,
        |           disaster        just exhaustion
        |           (End)           (End)
        |
        |
        renewable
        |\      |\
        | hydro | \
        |       |  \
        photo   |   \
        voltaic |    other
                |
                biomass



So it appears to come down to a stark choice between
breeder-reactors and various renewables.

Rick also makes the point that efficient renewable energy
sources are incompatible with many present-day energy uses.
This is a problem that requires serious attention.  But we
should not assume it is insoluble.

For example:  all-electric cars could be built, and would
be good enough for most purposes.  This does _not_ mean that
we need to have a "flag day" when we write off our entire
investment in cars.  Instead, we note that very few cars on
the road are more than 15 years old.  So we just arrange that
over a 25-year period or some such, we phase out gas-guzzlers
and phase in something else.  By way of analogy:  The rail lines
near me were gradually electrified over a many-year period.

And we need not adopt a one-size-fits-all approach.  Renewable
carbon-based fuels (corn oil or whatever) might be used for
specialized applications (perhaps military aviation) where
power-to-weight ratio is at a premium.  Of course one would
pay premium prices for this.

I don't have all the answers.  I haven't worked out the
details on any of this.  But it sure seems like an important
set of questions.