[ExI] Thoughts on Space based solar power (limited time?)
hkhenson at rogers.com
Sat Nov 22 20:25:56 UTC 2008
At 07:32 AM 11/22/2008, Paul wrote:
>>I am not even discussing space habitats when talking about power
>>sats in the current mode where all the parts have to come up from the earth.
>>There might be a few, perhaps even up to a thousand, people in GEO
>>monitoring the equipment that's turning out power sats but this
>>isn't what O'Neill had in mind. I frankly don't think there will
>>be any serious human habitation of space this side of the
>>singularity and after that who knows? In any case, humans as we
>>know them will not be in charge.
>OK, now I see where you are coming from. I had not understood that.
>Thanks for clarifying that. People move on to new things now and
>then. And sometimes they don't. Both are important at various times
>in our lives. :-)
>I've cared about space habitation since before I was ten
About the same age for me when my mom read me "Farmer in the Sky,"
something she bitterly regretted in later years. (She never approved
of L5 etc.)
>(probably no doubt in part indirectly due to your early efforts. :-)
>The possibilities of expansion into space is central to my views on
>the world (for good or bad), even as I have integrated that with
>ideas for sustainability on Earth. Space habitation I feel for sure
>is possible, as is making Bucky Fuller's "Spaceship Earth" work for
>everyone pretty much as it is. The singularity is a big unknown, we
>agree. But, we also don't know what role space habitation or an
>effort towards space habitation will play either. We don't know what
>role a positive vision of human life on Earth and in the universe
>may play in getting us a happier singularity. Which way do you want
>to bet if there are unknowns? :-)
>>>There are a lot of good reasons to develop space habitations. Cheap energy
>>>beamed back to Earth in the short term is not one of them IMHO.
>>Cheap energy beamed back to earth and used for such things as
>>making synthetic fuel out of water and carbon dioxide is a good
>>reason to develop space based solar power.
>It might well be.
>There is still the launch costs and hardware costs and such.
>Whatever hardware you put in space, it could get, with weather
>effects and the earth's day and night cycle, only about six times
>more power in space than on Earth (unless you exploit some important
>aspect of space, like mylar mirrors). But the cost and uncertainty
>of launching satellites and maintaining it are potentially huge.
>Also, again it requires a large capital investment in a coordinated
>way. Which means it is high risk. People can put up solar panels
>today on their own house. Maybe it is not cost effective yet in many
>places, but if you look at the trends it is growing more and more
>cost effective for more and more people.
There are parametric cost reasons to think it will never be cost
effective, at least not this side of nanotech.
The budget for power sats works out thus, $200/kW for the rectenna,
$200/kW for the power sat parts and $400 for lift and
construction. With an estimate of 4kg/kW, that requires the lift
cost to GEO to be down into the $100/kg range.
If we had the cable, a moving cable space elevator would probably get
the cost down in the range of $10/kg. Unfortunately we don't.
But as of this year there seems to be two methods, both starting with
relatively low performance rockets, that look like they will meet
this requirement. (High performance rockets, like going to LEO, are
exponentially more costly as you go up in delta V.) See the web site.
>>They may be a good idea, but there simply isn't time for them to happen
>>before the singularity.
>We just don't know -- that's the nature of the singularity.
In detail no. However, we can get there either of two ways, nanotech
will do to reverse engineer brains, and strong AI should be well up
to the task of designing nanotech. Given the onward march of
technology, I can't see this failing to happen by 2100. I don't even
see it holding out past mid century and could be even closer. If I
were confident it was within 5 years I wouldn't worry about energy,
we could get that far without a massive die off. But if it holds off
to mid century, we are in a world of hurt without power from
space--or some other really massive source of energy.
>So, we can ask ourselves what do we want as a vision of the future?
>Do we want to batten down the hatches and assume social collapse,
>and perhaps in making that assumption cause one? Or do we want to
>remain optimistic that endless possibilities await and continue to
>do things we think are productive?
>And if life is *already* a simulation, then how do we want to live
>it anyway? :-)
>We have no proof that strong (independent or swarm robotic) nanotech
>of the type Drexler suggests will ever exist. Thermal effects may
>render it infeasible or unstable (the heat dissipation required for
>that much coordinated communications and action). Nature has had at
>least billions of years to refine cellular machinery, perhaps
>billions more if it came from outside the solar system, and perhaps
>even longer than that if our ideas about the universe are wrong. And
>in all that time, nature missed something completely obvious that
>would spread across the universe?
>While I have little proof (beyond a gut feeling from graduate
>studies in Ecology and Evolution), I'm more of the opinion that the
>energetics of cells is about as good as it will ever be. That the
>replication times are the same no matter how you build them. That
>the biological world with a complex ecology is a tough place to
>survive for cells and we are not going to see some super stand-alone
>nanotech any time soon, even though we may see lots of nanomaterials
>or artifacts assembled on the nanoscale. Now, this does not mean we
>cannot wipe ourselves out with plagues -- I'm just talking about
>something appearing that is somehow way "better" than bacteria
>optimized over billions of years (bacteria essentially form a
>worldwide supercomputer exchanging genetic information across the
>globe in days or weeks).
>But neither of us can be sure.
>Let's say nature has missed something and strong nanotech is around
>the corner like in your story. We still don't know what will happen
>or when or how other events will shape it. Why abandon the simplest
>way to get some diversity of living spaces and a diversity of ideas
>of how to approach things as space habitats?
I would be working on space habitats if I thought there was any
chance of them happening pre singularity. I simply don't. If we set
up to build 500-1000 GW of new power sats a year, a side effect would
have a significant number of people working (and living) in
space. If we build the power sats out of Invar, perhaps the most
sensible material, then the nickel mines on earth get
exhausted. Perhaps if that happens someone will remember that nickel
is a major part of some asteroids and dedicate a power sat mass
(10,000t) to go mining asteroids. But these generate construction
housing and mining camp housing not O'Neill habitats. Sorry.
>The image of Earth from space has had a profoundly positive effect
>on our society, an effect so large it was IMHO worth a thousand
>times the cost of the space program just by itself:
>What else might we get by cooperatively reaching for more?
>In my opinion, if the singularity is a mirror of who we are (or want
>to be), then we should think hard on that.
> "What is the Mirror of Erised?"
>>I understand your points, but consider them to be way out of
>>date. Time marches on and the future isn't what it used to be. Sorry.
>If I'm arguing so strongly for emphasizing space habitations over
>SPS, think of it only as an echo from your previous successes. :-)
>Maybe you are right and will succeed at SPS systems as well. Time
>will tell. Thanks for the reply.
>Best of luck with your projects. And as I said before, when we get
>into space in a big way, and build those space habitats (O'Neill,
>Savage, Bernal, whatever design :-) we're going to need solar space
>satellites. So, technologically I think solar space satellites are a
>good idea and well worth designing and testing. It's more an issue
>of which way the microwaves are to be beamed -- towards Earth or
>towards space habitations. :-)
If you build a habitat, you connect it to the power plant with 99%
efficient _wires_ not a 50% efficient heavy and expensive microwave system.
>Anyway, sorry to take up so much list bandwidth on this topic.
Not a problem, the subject has to be reviewed once in while for new
people anyway. And as you can see there have been big conceptional
jumps this year.
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