[ExI] pentagon wants orbiting solar power stations

[hkhenson]

At 11:31 AM 10/16/2007, Samantha  wrote:

>On Oct 14, 2007, at 11:51 AM, hkhenson wrote:
>
> > At 10:46 PM 10/13/2007, Samantha  wrote:
> >
> >> On Oct 13, 2007, at 3:56 PM, hkhenson wrote:
>snip
> >>> Also, the biggest use of oil is transport fuel, and that not easy to
> >>> displace with fission.  It can be done, but the resultant fuel will
> >>> be very expensive.  See my discussion on dollar gasoline here a
> >>> while back.
> >>
> >> What kind of transport are we talking?  Some 60+% of oil used in the
> >> US is used by cars and trucks.  How many of them could run just fine
> >> off of electricity generated by nuclear power?
> >
> > Not very many of them.  But even if *half* could, it won't solve the
> > carbon and energy problem.
>
>Why can't all cars and light trucks be electric?

It's the same reasons we are having so many problems with trying to 
design and build electric cars now.  But you mentioned 
"trucks."  Every calculated how much energy it takes for a big truck 
to go over the passes in California?  The key to hydrocarbons is they 
are energy dense and 65% of the mass of the products comes from 
sucking in air.  Refueling an automobile from a gas pump is (from 
memory) 20 MWs thermal.  I.e., if you just burned the gas coming out 
of the pump, the flame would be 20 MW.  (For comparison, a large line 
locomotive at full power might produce 3 MW.)

>And why wouldn't a  substantial decrease in oil burned help?

Because you are not going to get it.  Any savings the US might manage 
are going to be sucked up other places in the world.  We have to 
displace oil and coal with something better.  Nuclear power is a 
relatively short term solution (limited supplies of uranium) and has 
really horrible risks.  If there were no other choice, I would 
reluctantly support it.  It may turn out there is no other choice if 
there is some engineering/physical reason we can't build SPS.

Keith Henson

PS, one alternative to abundant energy is some combination of war, 
starvation and disease that cuts the population back.  Oil supplies 
would last a lot longer if there were far fewer people.