[ExI] Engineering

[Keith Henson]

On Tue, Dec 18, 2012 at 4:00 AM, Adrian Tymes <atymes at gmail.com> wrote:
>
> On Mon, Dec 17, 2012 at 7:53 AM, Keith Henson <hkeithhenson at gmail.com> wrote:

snip

>> The problem with power satellites is *not* collecting power in space
>> or beaming it to the ground.
>
> Actually, it is *a* problem.  There may be larger problems, but
> that doesn't mean the smaller ones can be ignored.
>
> More importantly, demonstrating that you can solve what you
> are certain you can solve, directly helps with the bigger problem:
> getting the money to put the large satellite into space.

You forget that I have specifically disavowed raising money.  That's
beyond my skill set.

OK, if the people who can raise the money say they have to demonstrate
things like power beaming before they can raise the money, fine.  They
can raise the money to do whatever they think is needed to raise the
rest of the money.

snip

>> it's cheaper to set up the parts pipeline for hundreds of them
>> than it is to build just one.
>
> Actually, when you factor in the cost of capital acquisition
> on this scale, it might prove to be cheaper to build just one.

Let's put numbers on it.  One power sat, 25,000,000 kg x $10,000 per
kg, $250 B for the transport alone.   Setting up the parts pipeline
and building the first one I have estimated at $140 B.

> (At least at first: costs come down the more financiers can
> be certain that not only will the idea work, but that you - or
> whatever specific persons are doing the asking - can in
> fact pull it off.  This is why startups and large companies
> make such a big deal over who their CxOs are - you and I
> might see it as overhyped, but the people who provide the
> money think differently than you and I.)

There I agree with you.  One high powered CEO required.  What would
you think of David Petraeus in that role?

 "Andrew Mckee" <andymck35 at gmail.com> wrote:
>
> On Sun, 16 Dec 2012 07:34:58 +1300, Keith Henson <hkeithhenson at gmail.com> wrote:
>
>>> From: "Andrew Mckee" <andymck35 at gmail.com>
>>> Is chasing 100% utilization really worth the expense of putting a PV array in orbit?
>>>
>>> What am I missing here?
>>
>> Lots.  Particularly transmission cost and storage costs.
>
> Maybe not so much, I caught your original post about StratoSolar a while back.
> And like many commentators on TOD had the initial reaction that even if a tethered solution could work from an engineering perspective, the NIMBY crowd are going to a have field day tearing that proposal to shreds.
>
> IMHO seems like a better idea to go untethered so the array can be put anywhere the NIMBYs can't object to it,

And how are you going to keep it there?  The subject has been
considered in depth by people who want a platform they can keep over
disputed territory like Afghanistan and earlier, Iraq.  Some of the
time there is enough power from the solar cells to keep it in place.
But far below the maximum expected wind it can't station keep and gets
blown down wind.  Now you have it crossing boarders like Iran and
Russia.

> and as already pointed out use the power generated to extract water from the lower atmosphere and make some kind of liquid fuel from it.
> I picked liquid hydrogen,

I have looked into producing LH2 in vast amounts since a power
satellite project uses upwards of 240 tons per hour.
http://www.scribd.com/doc/46580743/A-Future-Energy-Chain-Based-on-Liquefied-Hydrogen
 But I have not considered the mass of the machines needed to make and
liquefy the hydrogen.  It may be in the tens of thousands of tons.
Storage is going to be difficult too.

> more as a convenience factor since I envisioned a lot of hydrogen being needed just to lift everything required in the first place, plus its possible use in a gazillion fuel cells when that long overdue thing called the hydrogen fuel economy actually starts becoming a significant reality.

>> And just how do you propose to move power plants from the arctic?
>
> Power plants???, if you mean shifting energy around, I would've gone for using high altitude airships shipping liquid hydrogen to where its needed much like the oil industry does currently.
>
> If you meant the stratospheric PV arrays, I imagined the rafts being built as semi rigid modules with tilting PV panels on the roof and storage and directional thrusters bolted underneath so that the modules can transport themselves around and contribute to the yearly migration to and from the polar skies.

This might be possible without burning off too much hydrogen during the move.

>> I know a good deal about this topic.  http://www.theoildrum.com/node/8323
>
> Yep, no worries, as far as I'm concerned your THE GotoGuy for advice on such matters.
>
>> If you really want to go through the details, ask.  Though there are...
>
> Well I am still somewhat puzzled why you seem to be a frequent supporter of space based solar despite the number of show stopping problems it faces, but seem (and it could be just me) somewhat less enthusiastic about StratoPV type approaches when it seems that they could be pressed into service for far less cost, and without any great technology breakthroughs as far as I can see.

On the prospect that StratoSolar could make power for a lower cost
than power satellites, I worked on it for about two years.  It finally
developed so many engineering problems that Ed Kelly was forced from
the thermal type into a PV design that was more likely to work but
more expensive than what is required to displace fossil fuels (and
while it is above the clouds, it has the night problem of ground
solar).  And even so, that design has a number of unsolved problems.

> Apologies in advance if I've simply misread your intention's, but it's in the back of my mind that maybe you have stated somewhere I've missed (entirely possible) that stratospheric structures can't work with our current level of technology due to the e.g. 180 km/h winds blowing through the stratosphere every few years wrecking any structure we can build that can float that high.

We can probably cope with the winds even with tethered units, though
it complicates the design.  If you can just let them float downwind,
then there is relatively little force on them, only the shear forces.
I know someone who is interested in this concept.  I don't know if he
has done the mass estimates, will ask.

Keith