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Paul F. Dietz
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 Posted: Tue Jun 05, 2007 3:48 pm Post subject: Re: Bush and VSE (was Re: Breaking News! NASA Astronaut Mars |
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John Schilling wrote:
| Quote: |
SSP doesn't connect to oil prices, because SSP generates electricity and
oil is almost exclusively used in applications where electricity is *not*
an adequate substitute.
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And to the degree that electricity can better become a substitute for
petroleum (for example, by improvements in batteries for vehicles)
then SSP isn't needed, or even particularly helpful. Huge numbers of
PHEVs could be charged on the US power grid with existing capacity
(mostly during off-peak times) before they would require new capacity
additions.
Paul |
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Joe Strout
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| Posted: Tue Jun 05, 2007 8:11 pm Post subject: Re: Bush and VSE (was Re: Breaking News! NASA Astronaut Mars |
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In article <vcj963lp1o6ilgkti6m5jn46sskgpsm5oj@4ax.com>,
John Schilling <schillin@spock.usc.edu> wrote:
| Quote: |
SSP doesn't connect to oil prices, because SSP generates electricity and
oil is almost exclusively used in applications where electricity is *not*
an adequate substitute. You're thinking about "energy" as if it were a
fungible commodity; it's not. There are two almost completely independant
energy markets, one for fixed power and one for motor vehicle fuel.
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This will cease to be true when/if motor vehicles run primarily on
stored electricity. Try <http://www.google.com/search?q=Tesla+motors>
for example.
| Quote: |
SSP is doubly irrelevant to the war because A: see above, and B: SSP can
not possibly be brought on line in significant quantity until the war is
long since won or lost.
|
Well, (B) is true for my lunch too, given that the war has long since
been lost. :)
| Quote: |
And SSP is somewhat relevant to global warming, but mostly to the extent
that it replaces Chinese coal-fired power plants and blast furnaces. But
any plan to devote Sagans of American taxpayer dollars to building new and
better power plants for the Chinese, is an absolute political non-starter.
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China is certainly important, but the US is at the top of total CO2
emissions at least as of 2003:
http://cdiac.ornl.gov/trends/emis/tre_tp20.htm
Of course I realize that what matters is current and near-future
emissions, not total past emissions. But the U.S. is at the head of
that "current" list too, at least as of 2005:
http://www.earth-policy.org/Indicators/CO2/2006_data.htm
Granted, China's got a lot of power coming online in the near future,
but it's extreme head-in-the-sand-ism to say that US emissions don't
matter. We're responsible for over 20% of the CO2 emitted on the
planet. That's huge.
| Quote: |
Furthermore, SSP is *percieved* as being absolutely completely totally
irrelevant to anything in the real world, on account of being a hopelessly
unrealistic fantasy.
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No argument there. Of course if it were demonstrated, even on a small
scale, people would stop laughing. But as long as they're laughing,
it's hard to demonstrate. This is the classic problem space development
has faced over and over, occasionally with success (e.g. space tourism).
| Quote: |
We need clean solutions to global warming and fossil fuels.
Which SSP may not offer, and even if it does, how do you propose to get
it? Shouting for massive government spending to develop SSP technology,
however you propose to structure the program this time, *will not work*.
And damn few of us will join you on that fool's errand.
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True. About the only hope I have for SSP is for some visionary business
leader to do it -- maybe Richard Branson, who has deep pockets and an
obvious interest in both space development and clean energy. But I
don't imagine that there's much we can do here to have any influence on
it at all.
Best,
- Joe |
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Joe Strout
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| Posted: Tue Jun 05, 2007 8:14 pm Post subject: Re: Bush and VSE (was Re: Breaking News! NASA Astronaut Mars |
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In article <FMKdnd_dj4UP0PjbnZ2dnUVZ_qemnZ2d@dls.net>,
"Paul F. Dietz" <dietz@dls.net> wrote:
| Quote: |
John Schilling wrote:
SSP doesn't connect to oil prices, because SSP generates electricity and
oil is almost exclusively used in applications where electricity is *not*
an adequate substitute.
And to the degree that electricity can better become a substitute for
petroleum (for example, by improvements in batteries for vehicles)
then SSP isn't needed, or even particularly helpful. Huge numbers of
PHEVs could be charged on the US power grid with existing capacity
(mostly during off-peak times) before they would require new capacity
additions.
|
It's not just about adding new capacity as needed -- it's about reducing
existing emissions, by replacing existing fossil-fuel-burning plants.
But maybe I'm missing the point here, which was merely about oil prices.
For that I agree, widespread electric vehicles alone would reduce oil
prices without SSP.
Best,
- Joe |
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Henry Spencer
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| Posted: Tue Jun 05, 2007 9:46 pm Post subject: Re: Bush and VSE (was Re: Breaking News! NASA Astronaut Mars |
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In article <FMKdnd_dj4UP0PjbnZ2dnUVZ_qemnZ2d@dls.net>,
Paul F. Dietz <dietz@dls.net> wrote:
| Quote: |
And to the degree that electricity can better become a substitute for
petroleum (for example, by improvements in batteries for vehicles)
then SSP isn't needed, or even particularly helpful. Huge numbers of
PHEVs could be charged on the US power grid with existing capacity
(mostly during off-peak times) before they would require new capacity
additions.
|
With one small caveat: some of the generating capacity now used only for
peak loads, which would have to run 24x7 if some new big off-peak energy
use appeared, is not suited to providing base-load power -- too expensive,
too polluting, etc. (Some utilities use older plants, or inefficient but
low-capital-cost technologies like gas turbines, to help meet peak loads.)
It would have to be replaced with new base-load generating capacity in
this scenario.
That's a detail, though; Paul is still basically correct.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net |
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Henry Spencer
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| Posted: Tue Jun 05, 2007 10:20 pm Post subject: powersats (was Re: Bush and VSE) |
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In article <e7Z8i.13483$296.4237@newsread4.news.pas.earthlink.net>,
robert casey <wa2ise@ix.netcom.com> wrote:
| Quote: |
...a pilot plant has to *be* an operational system in all but size.
If it can't deliver hundreds of megawatts 24x7 to the power grid, it's not
a pilot plant.
Something capable of that would likely need to be built in place...
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Almost. You couldn't build it on the ground; you'd have to assemble in
orbit, at the very least. But you can consider building it in an orbit
different from its final operation orbit. Yes, it's big and heavy, but it
has *lots* of power available for electric propulsion (ion rockets etc.),
so it is not as hard to move as you might think, if you're not in a rush.
This is particularly helpful for powersats in geostationary orbit, which
is in the fringes of the outer Van Allen belt and gets enough radiation to
complicate long-term manned operations. (For that matter, most any likely
powersat orbit has the same caveat. The non-geostationary concepts mostly
want to operate closer in, not farther out.) You'd assemble in LEO for
Earth-launched concepts, and in very high orbit if you're going to get
most of the materials from the Moon.
| Quote: |
It's probably a lot cheaper to just build the solar power plant on the
ground (like in a desert in Arizona), even though it can only work
during the daytime. But power consumption does peak during the daytime...
|
Unfortunately, even Arizona gets clouded out at times, and atmospheric
absorption cuts available power early and late in the day (a particular
annoyance for the latter, since that's when the highest demand peak is).
And there is quite a bit of 24x7 base load to be supplied, and there'll
be much more of that if electricity is used to manufacture or replace
petroleum-derived liquid fuels.
(Also note that ground solar plants contribute, a little bit, to global
warming! Deserts mostly are quite reflective, with much of the incoming
energy going back out into space. But a power plant captures almost all
incoming light, and much of it ends up as waste heat at the power plant.
For power generation on a many-gigawatt scale, this isn't entirely
negligible. Powersats do the inefficient part outside the biosphere.)
Daytime-only solar power generation has some uses, but it's a specialized
niche technology, ill-suited to taking over a large fraction of our energy
needs. To be more generally useful, it would have to be backed up with
some highly effective energy-storage technology, and that's really hard to
do (except in a few favorable locations where pumped hydroelectric storage
is practical).
| Quote: |
...And you don't need to convert the power to RF and back again.
|
Actually, conversion to RF and back is more efficient than long-haul
transmission by high-voltage power lines. (Long-haul transmission is
currently fairly minor -- most power is generated close to its users --
but that would have to change for large-scale use of ground solar.)
| Quote: |
And access for building it and maintenance is nothing out of the ordinary.
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Powersats do require a big up-front investment in space transportation.
Once that's done, though, access for building and maintenance *would* be
nothing out of the ordinary. You can't realistically hope to build and
operate powersats with the sort of space transportation we've got now --
it's a whole new order of magnitude -- so the current situation, in which
access to space is difficult and infrequent, simply isn't relevant.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net |
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robert casey
Guest
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| Posted: Tue Jun 05, 2007 11:47 pm Post subject: Re: Bush and VSE (was Re: Breaking News! NASA Astronaut Mars |
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| Quote: |
No, it doesn't need to be--that's only one potential architecture.
The benefit of GEO is that you can get continuous service from a
single satellite, whereas lower altitudes require a constellation of
them. However, the latter would be easier to demonstrate with a
part-time system, which would be a proof of concept for the whole
constellation.
|
Powersats in LEO to me doesn't seem to be much better than just building
the thing on the ground. At night, a powersat visible from the ground
will probably also be in the Earth's shadow. So why bother putting it
in orbit? Getting something that big in orbit is way too expensive
anyway, and if the thing is built on the ground, you can skip the
conversion of the power to microwaves, and skip the rectennas. That
would cut losses by something like 40% or more. And doing repairs and so
on would be way easier with it on the ground. Of course it would only
generate power during the daytime, but that's when electricity usage
peaks anyway. And of course we'll need other power plants at night, but
we'd want multiple methods of power generation anyway. Windmills,
nukes, and so on. |
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Rand Simberg
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| Posted: Tue Jun 05, 2007 11:51 pm Post subject: Re: Bush and VSE (was Re: Breaking News! NASA Astronaut Mars |
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On Tue, 05 Jun 2007 19:47:18 GMT, in a place far, far away, robert
casey <wa2ise@ix.netcom.com> made the phosphor on my monitor glow in
such a way as to indicate that:
| Quote: |
No, it doesn't need to be--that's only one potential architecture.
The benefit of GEO is that you can get continuous service from a
single satellite, whereas lower altitudes require a constellation of
them. However, the latter would be easier to demonstrate with a
part-time system, which would be a proof of concept for the whole
constellation.
Powersats in LEO to me doesn't seem to be much better than just building
the thing on the ground.
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I didn't say LEO. Just an orbit much closer to earth to reduce the
size of the transmitting antenna. Satellites that are eclipsed would
be supplemented by others from the constellation, with split beams. |
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Derek Lyons
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| Posted: Wed Jun 06, 2007 1:23 am Post subject: Re: Bush and VSE (was Re: Breaking News! NASA Astronaut Mars |
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henry@spsystems.net (Henry Spencer) wrote:
| Quote: |
In article <FMKdnd_dj4UP0PjbnZ2dnUVZ_qemnZ2d@dls.net>,
Paul F. Dietz <dietz@dls.net> wrote:
And to the degree that electricity can better become a substitute for
petroleum (for example, by improvements in batteries for vehicles)
then SSP isn't needed, or even particularly helpful. Huge numbers of
PHEVs could be charged on the US power grid with existing capacity
(mostly during off-peak times) before they would require new capacity
additions.
With one small caveat: some of the generating capacity now used only for
peak loads, which would have to run 24x7 if some new big off-peak energy
use appeared, is not suited to providing base-load power -- too expensive,
too polluting, etc. (Some utilities use older plants, or inefficient but
low-capital-cost technologies like gas turbines, to help meet peak loads.)
It would have to be replaced with new base-load generating capacity in
this scenario.
|
Two small caveats: some of the power currently sold East-to-West (and
vice versa) will instead be used locally during off peak hours.
| Quote: |
That's a detail, though; Paul is still basically correct.
|
Agreed.
D.
--
Touch-twice life. Eat. Drink. Laugh.
-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL |
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John Doe
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| Posted: Wed Jun 06, 2007 1:25 am Post subject: Re: Bush and VSE (was Re: Breaking News! NASA Astronaut Mars |
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Re : Space Solar Panels replacing petrol in cars.
People forget that in the USA, a signififant percentage of electricity
is produced with polluting coal. This is a major source of pollution for
the planet. So if you can get alternative sources of electricity, it
will alleviate this very nasty source of pollution. It may not fir the
car problem, it helps fix another problem. |
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Hyper
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| Posted: Wed Jun 06, 2007 1:32 am Post subject: Re: Bush and VSE (was Re: Breaking News! NASA Astronaut Mars |
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On Jun 5, 10:47 pm, robert casey <wa2...@ix.netcom.com> wrote:
| Quote: |
No, it doesn't need to be--that's only one potential architecture.
The benefit of GEO is that you can get continuous service from a
single satellite, whereas lower altitudes require a constellation of
them. However, the latter would be easier to demonstrate with a
part-time system, which would be a proof of concept for the whole
constellation.
Powersats in LEO to me doesn't seem to be much better than just building
the thing on the ground. At night, a powersat visible from the ground
will probably also be in the Earth's shadow.
|
In shadow only twice a year during equinoxes, and only for an hour or
so per day.
| Quote: |
So why bother putting it in orbit? Getting something that big in orbit is way too expensive
anyway, and if the thing is built on the ground, you can skip the
conversion of the power to microwaves, and skip the rectennas. That
would cut losses by something like 40% or more. And doing repairs and so
on would be way easier with it on the ground. Of course it would only
generate power during the daytime, but that's when electricity usage
peaks anyway. And of course we'll need other power plants at night, but
we'd want multiple methods of power generation anyway. Windmills,
nukes, and so on.
|
Envisioned power loss (due to atm.) about 5%.
Advantages:
1. roughly double efficiency - no atm.;
2. +30% approx. depends on location of equivalent Earth based array -
no weather;
3. double that again for 24/7 operation - no night life  )
Disadvantage: requires *really* cheap launches. IIRC, $100/kg would
just about do it, for Moon produced arrays.
IMHO, nukes are the only reasonable way to cut CO2. They would replace
the worst source of pollution - coal. Incidentally, nukes would also
*diminish* radioactive waste released into the atm.
FYI http://www.ornl.gov/info/ornlreview/rev26-34/text/colmain.html |
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Joe Strout
Guest
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| Posted: Wed Jun 06, 2007 1:52 am Post subject: Re: Bush and VSE (was Re: Breaking News! NASA Astronaut Mars |
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In article <a5j9i.16988$Ut6.15996@newsread1.news.pas.earthlink.net>,
robert casey <wa2ise@ix.netcom.com> wrote:
| Quote: |
Powersats in LEO to me doesn't seem to be much better than just building
the thing on the ground.
|
That's OK; this is no doubt just because you haven't looked into them
very deeply.
| Quote: |
At night, a powersat visible from the ground
will probably also be in the Earth's shadow.
|
Incorrect. A satellite in GEO is in sunlight 24 hours a day, except for
a brief eclipse for about 20 minutes (IIRC) twice a year.
| Quote: |
and if the thing is built on the ground, you can skip the
conversion of the power to microwaves, and skip the rectennas. That
would cut losses by something like 40% or more.
|
Wrong again. Conversion to microwaves and back is extremely efficient
-- around 90% is reasonable to expect.
| Quote: |
Of course it would only generate power during the daytime, but that's
when electricity usage peaks anyway.
|
We need to serve baseline power, not just peak power. And as Henry
points out, the daytime peaks may well smooth out as we start
substituting other energy sources for transportation. (Cars will be
charged and synthetic fuels will be generated whenever power is
cheapest.)
Best,
- Joe |
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Joe Strout
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| Posted: Wed Jun 06, 2007 1:55 am Post subject: Re: Bush and VSE (was Re: Breaking News! NASA Astronaut Mars |
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In article <1181079128.135114.282920@q75g2000hsh.googlegroups.com>,
Hyper <hyperboreea@yahoo.com> wrote:
Unless, of course, Bussard's approach to fusion can be made to work. It
certainly looks promising from the preliminary data -- it's appalling
that it's not getting a drop of funding.
http://www.strout.net/info/science/polywell/
(Incidentally, I've donated $50 to this research; if you see any merit
in it, I encourage you to donate whatever you can as well. Waiting for
government or angels to step in doesn't seem to be working.)
Best,
- Joe |
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Wayne Throop
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| Posted: Wed Jun 06, 2007 1:56 am Post subject: Re: Bush and VSE (was Re: Breaking News! NASA Astronaut Mars |
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:: Powersats in LEO to me doesn't seem to be much better than just
:: building the thing on the ground. At night, a powersat visible from
:: the ground will probably also be in the Earth's shadow.
: Joe Strout <joe@strout.net>
: Incorrect. A satellite in GEO is in sunlight 24 hours a day, except
: for a brief eclipse for about 20 minutes (IIRC) twice a year.
OK, but how does what happens to a satellite in GEO make that claim
about LEO incorrect?
Mind you, nobody was proposing a LEO SPS upthread, but if anybody had,
I'd agree there are quite a few problems with the notion.
Wayne Throop throopw@sheol.org http://sheol.org/throopw |
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Joe Strout
Guest
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| Posted: Wed Jun 06, 2007 1:57 am Post subject: Re: Bush and VSE (was Re: Breaking News! NASA Astronaut Mars |
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In article <joe-FAECAA.15524105062007@comcast.dca.giganews.com>,
Joe Strout <joe@strout.net> wrote:
| Quote: |
In article <a5j9i.16988$Ut6.15996@newsread1.news.pas.earthlink.net>,
robert casey <wa2ise@ix.netcom.com> wrote:
Powersats in LEO to me doesn't seem to be much better than just building
the thing on the ground.
That's OK; this is no doubt just because you haven't looked into them
very deeply.
At night, a powersat visible from the ground
will probably also be in the Earth's shadow.
|
Oops -- sorry, you said LEO, and my brain read it as GEO.
You're right, a LEO powersat doesn't make too much sense, though one in
a somewhat higher (even if below GEO) satellite might. That's one of
those continuous engineering trade-offs, that would require running some
real numbers (and detailed other assumptions) to find an optimum.
Best,
- Joe |
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Rand Simberg
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| Posted: Wed Jun 06, 2007 2:13 am Post subject: Re: Bush and VSE (was Re: Breaking News! NASA Astronaut Mars |
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On Tue, 05 Jun 2007 14:32:08 -0700, in a place far, far away, Hyper
<hyperboreea@yahoo.com> made the phosphor on my monitor glow in such a
way as to indicate that:
| Quote: |
On Jun 5, 10:47 pm, robert casey <wa2...@ix.netcom.com> wrote:
No, it doesn't need to be--that's only one potential architecture.
The benefit of GEO is that you can get continuous service from a
single satellite, whereas lower altitudes require a constellation of
them. However, the latter would be easier to demonstrate with a
part-time system, which would be a proof of concept for the whole
constellation.
Powersats in LEO to me doesn't seem to be much better than just building
the thing on the ground. At night, a powersat visible from the ground
will probably also be in the Earth's shadow.
In shadow only twice a year during equinoxes, and only for an hour or
so per day.
|
That's the case only for GEO. We were talking about LEO. |
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