[ExI] Written for another list

[Keith Henson]

On Mon, Jul 30, 2012 at 5:00 AM,  Adrian Tymes <atymes at gmail.com> wrote:

> Demonstrate it at lower cost with existing technology
> first, even if you have to accept a much, much slower
> rate of payback at first.

There might be a way to do this, but I don't know how.  The people who
have really studied this, for example,

http://www.sspi.gatech.edu/aiaa-2009-0462_ssp_alternatives_potter.pdf

get numbers around a dollar a kWh.  That's acceptable for powering
lasers, but I can't see much of a market for multiple GW at 20 times
the cost of electricity from nuclear plants.

> If what you say is true, then it should be possible to
> achieve profitability in several years with chemical
> propulsion alone, even assuming the amount you're
> squirreling away for R&D on the better-cheaper laser
> propulsion gets wasted.

I can send you the spreadsheet for the financial model if you want to
try making money on conventional propulsion.

> If it is not, then the rest of your model is probably bogus.

Perhaps.  I freely admit the model may have errors in assumptions or
formula.  Though saying that without looking at the model seems a bit
over the top.

> That is what most investors will tell you.

I have no  present intention of showing this project to investors.
For one thing, I am assured that there is only one, the Chinese
government.  That is already underway.

I am mainly interested in making a case that there *is* a way out of
the energy/carbon problems without an 80% die off.

> From: john clark <jonkc at bellsouth.net>
>
> On Sun, Jul 29, 2012? Keith Henson <hkeithhenson at gmail.com> wrote:
>
>>? The energy payback from power satellites is short, two months
>
> I think that's a pretty useless figure

Wind and solar runs about two years.

> because the problem is not the high cost of rocket fuel.

It never has been.  The cost of hydrogen is a few dollars per kg to
GEO in this model.

> In fact even if the launch cost to geosynchronous orbit were zero I'm not at all sure power satellites would be economically viable.?

The cost of power at current $10,000/kg is dominated by the lift cost
of ~50,000/kW.  Cost of power at that transport rate is ~$2/kWh.

For zero lift cost, the cost would be around 1.4 cents per kWh.  The
derivation of this is in the paper.

> I think liquid fluoride thorium reactors are a much better bet and we already have the technology or nearly so, we've had most of it since the 1960's, and that is pretty amazing considering the tiny amount of money spent developing the concept.? About half a century ago we made a blunder and turned to solid fuel uranium reactors and not to liquid fuel thorium reactors and we've been paying a huge price for that mistake ever since.

First, will thorium scale to 10s of TW?  If it will, i.e., there is
enough, how much capital investment per kW?  Make a convincing case
it's possible and less expensive than power sats and I will work on
that instead.

I am concerned with solving the problem and am not that particular as
to how.  Google oil drum stratosolar.

Keith

Keith