Limits to Growth

10 views
Skip to first unread message

Bill Woods

unread,
Apr 14, 2000, 3:00:00 AM4/14/00
to
Pete McCutchen wrote:

> On Thu, 13 Apr 2000 15:29:54 -0700, Samuel Paik <pa...@webnexus.com>
> wrote:
>
> >William December Starr wrote:
> >> What kind of energy per square meter would be hitting the ground under
> >> the proposed [solar power satellite] designs? Is it enough to worry about
> >> if somebody nasty _worked_ at making the beam wander?
> >
> >Something like 1 kW/m^2 -- about the same as sunlight. Rectennas should
> >be around 90% efficient at conversion to electricity. If you use a pilot
> >beam to focus a phased array, then on pilot beam loss the array defocuses.
>
> OK, bear with me when I ask a (concededly) ignorant question. How
> efficient are solar cells? How efficient would they have to be, at
> what price, to compete with traditional power-generation methods?

Geoffrey Landis or George Herbert could give a better answer,
but I think the best get ~30%. Cheaper ones get ~10-20%. umm..

http://www.eia.doe.gov/cneaf/solar.renewables/rea_data/html/front-1.html#highlights

Renewable Energy Annual 1998

Industry Developments

Siemens Solar Industries announced delivery of a record-efficient,
1-kilowatt (peak) thin-film photovoltaic array to the National
Renewable Energy Laboratory (NREL). The 28-module array has an
average module power of 39 watts peak (Wp) and an efficiency of
9 percent. The modules incorporate Siemens' newest improvement
in copper-indium-diselenide-based thin-film technology, which
was developed with support from NREL's Thin-Film PV Partnership
Program. The best module of the array produced 40.6 Wp for a
record efficiency of 11.1 percent.

AstroPower Inc. announced it bested its previous sunlight-to-
electricity conversion efficiency record and fabricated a
16.6 percent efficient thin-film silicon solar cell under
a collaboration with the NREL. The record was set on a
laboratory-scale device measuring 1 square centimeter as part
of the Department of Energy's Photovoltaic Manufacturing
Technology Initiative. The prior record, set a few years ago,
was 14.6 percent.


http://www.eia.doe.gov/cneaf/solar.renewables/rea_data/html/chapter2.html#4
Values and Prices

The total value of photovoltaic module and cell shipments was
$175 million in 1997, a 34-percent increase over the 1996 value
of $131 million (Table 29). ... The average price of crystalline
silicon modules in 1997 was $4.06 per peak watt, an increase of
3 percent from the 1996 price of $3.95 (Table 29).

With clear skies you get about 6 * Wp watt-hrs per day for
a fixed array, or about 2 * Wp kW-hr per year. If you borrow
$4 per Wp at 10%, that will cost you 20¢ / kW-hr, just for the
PV modules. Other equipment add to the total, so you still need
to be a few miles off the grid for solar power to be cost-effective.

http://www.eia.doe.gov/cneaf/electricity/epav1/epav1ta15.html
Average Revenue per Kilowatthour for U.S. Electric Utilities 1998
New Hampshire 11.8 [¢]
Hawaii 11.5
Pennsylvania 7.7
US average 6.75
Idaho 4
Washington 4

http://rredc.nrel.gov/solar/codes_algs/PVWATTS/
PVWATTS calculates electrical energy produced by a grid-connected
photovoltaic (PV) system. Currently, PVWATTS can be used for
locations within the United States and its territories, which
are accessible through links on the U.S. map located below.
Researchers at the National Renewable Energy Laboratory developed
PVWATTS to permit non-experts to quickly obtain performance
estimates for grid-connected PV systems.

--
Bill Woods

"The hardest thing in the world to understand is the income tax."

-- Albert Einstein

George Herbert

unread,
Apr 15, 2000, 3:00:00 AM4/15/00
to
Bill Woods <wwo...@ix.netcom.com> wrote:
>Pete McCutchen wrote:
>> On Thu, 13 Apr 2000 15:29:54 -0700, Samuel Paik <pa...@webnexus.com>
>> >William December Starr wrote:
>> >> What kind of energy per square meter would be hitting the ground under
>> >> the proposed [solar power satellite] designs? Is it enough to worry about
>> >> if somebody nasty _worked_ at making the beam wander?
>> >
>> >Something like 1 kW/m^2 -- about the same as sunlight. Rectennas should
>> >be around 90% efficient at conversion to electricity. If you use a pilot
>> >beam to focus a phased array, then on pilot beam loss the array defocuses.
>>
>> OK, bear with me when I ask a (concededly) ignorant question. How
>> efficient are solar cells? How efficient would they have to be, at
>> what price, to compete with traditional power-generation methods?
>
>Geoffrey Landis or George Herbert could give a better answer,
>but I think the best get ~30%. Cheaper ones get ~10-20%. umm..

I think that's right for the best; Geoffrey does cutting edge solar
cell stuff for his day job, so presumably he'll be weighing in with
detailed information as time allows.

Current best space rated non-concentrating cells are heading past
25% efficiency at beginning of life. Space rating requires radiation
resistance and other features on top of basic power conversion.
Typical end of life performance for those cells is 18%.

If you're talking seriously about surface solar power plants, you don't
want to use the best solar cells. Land is cheap (cents to tens of cents
per square meter) but solar cells are not (dollars to hundreds of dollars
per square meter). As it turns out, the optimal solar cells for ground
power plants are the cheapest ones, amorphous silicon cells, which run
around 10% efficient.

>[...]


>With clear skies you get about 6 * Wp watt-hrs per day for
>a fixed array, or about 2 * Wp kW-hr per year. If you borrow
>$4 per Wp at 10%, that will cost you 20¢ / kW-hr, just for the
>PV modules. Other equipment add to the total, so you still need
>to be a few miles off the grid for solar power to be cost-effective.

Right, best estimates are that current cells are about a factor
of three too expensive for ground power, but there's a significant
price drop curve in effect as production volume increases and
as the technologies improve and mature, with expected crossover
to net parity with current base load costs around 2006 if the
curve stays constant and grid power costs stay about the same.


-george william herbert
gher...@crl.com


George Herbert

unread,
Apr 15, 2000, 3:00:00 AM4/15/00
to
Note added xpost to .science and followups directed there.

Larry Caldwell <lar...@teleport.com> wrote:
>jsba...@aol.com writes:
>> >I would be just as anxious as anyone that any large-scale deployment
>> >of OTEC be closely monitored and any effects on biota, currents, and
>> >climate noted.
>> Including the safety of the system after being deployed for 50,000 years?
>
>This tells me you have never lived near an ocean. Anything on the ocean
>is lucky to survive for 20 years, and 50,000 is absurd. We don't have
>any building materials that would survive the combination of
>encrustation, corrosion, flexing and hammering for long.
>It's another one of those fantasy inventions like orbital elevators.

I have a degree in Naval Architecture and Offshore Engineering.
20 years is a lot shorter than design lifetime for offshore structures
and ships (40 years is more typical, which is really that it still be
in adequately safe shape with margins 40 years down the line, not that
it not fall apart until 40 years and a day). Many survive a lot longer
than that in good working order, though a lot of ships were built in the
70s and 80s which were sort of sketchy on margins.

Minor material changes and margins increases would increase structural
life up past 100 years easily; using monel, and allowing for 1.5-2x
the current standard scantlings, would get you there easily, perhaps
out to 250 years. Monel does dissolve slowly in seawater, so it would
have to be either very very thick or actively protected to last for
thousands of years (very large structures, or very high structural
fraction of total displacement).

There are several possible materials with good structural strength
and positive galvanic potential which should be suitable for building
structures of arbitrarily long lifetimes, various nickel alloys and
titanium and possibly tungsten, though I am not sure of its galvanic
potential. Some ceramics would probably do well too; alumina fiber
in a lower melting temp ceramic matrix, etc.


-george william herbert
gher...@crl.com


Samuel Paik

unread,
Apr 15, 2000, 3:00:00 AM4/15/00
to
In article <8dah0v$7...@crl3.crl.com>, gher...@crl3.crl.com (George

Herbert) wrote:
> power plants are the cheapest ones, amorphous silicon cells, which run
> around 10% efficient.

Any idea on the efficiency and cost of solar thermal?

Sam
my ISP's news server seems to be down right now...


Sent via Deja.com http://www.deja.com/
Before you buy.

Pete McCutchen

unread,
Apr 16, 2000, 3:00:00 AM4/16/00
to
On 15 Apr 2000 12:47:43 -0700, gher...@crl3.crl.com (George Herbert)
wrote:

>Right, best estimates are that current cells are about a factor
>of three too expensive for ground power, but there's a significant
>price drop curve in effect as production volume increases and
>as the technologies improve and mature, with expected crossover
>to net parity with current base load costs around 2006 if the
>curve stays constant and grid power costs stay about the same.

Wow. I hadn't realized that it was that close to being economical.

I assume that it matters where you are, though. Arizona would
probably be a better place than, say, Chicago.

--

Pete McCutchen

George Herbert

unread,
Apr 16, 2000, 3:00:00 AM4/16/00
to
Pete McCutchen <p.mcc...@worldnet.att.net> wrote:
>gher...@crl3.crl.com (George Herbert) wrote:
>>Right, best estimates are that current cells are about a factor
>>of three too expensive for ground power, but there's a significant
>>price drop curve in effect as production volume increases and
>>as the technologies improve and mature, with expected crossover
>>to net parity with current base load costs around 2006 if the
>>curve stays constant and grid power costs stay about the same.
>
>Wow. I hadn't realized that it was that close to being economical.

Yep, knocking on wood but it doesn't appear that far out.

>I assume that it matters where you are, though. Arizona would
>probably be a better place than, say, Chicago.

Definitely. The further you have to transport the power the
more expensive it is, so this will start to be commercially viable
for local power in sunny regions and then spread as costs drop.

Two things it can't do is completely replace existing fossil
fuel and provide 24x7 power. Nighttime base load is significant
and cannot be addressed by solar power (except perhaps with pumped
storage, which is geographically difficult in most areas... the cost
of batteries or flywheels or capacitors to store that much is just
unreasonably prohibitive). If you want mostly clean power but not
requiring entirely zero emissions, the cheapest system will probably
be a combination of solar for day loads with natural gas power for
night loads and cloudy days. If you require zero emissions then
you have to either invest in pumped storage, or nuclear, or some
serious intercontinental long distance power interties and import
your night loads from places the sun is up. Solar power satellites
might also be cost effective for nighttime power loads in 20 or
more years, depending on the state of space development, but the
daytime load (and by far most of the kWhr used over the course of
a full day cycle) will most likely be most cheaply provided by
ground solar.


-george william herbert
gher...@crl.com


Paul F Austin

unread,
Apr 16, 2000, 3:00:00 AM4/16/00
to

"Samuel Paik" <pa...@webnexus.com> wrote in message
news:8dap0l$3es$1...@nnrp1.deja.com...

> In article <8dah0v$7...@crl3.crl.com>, gher...@crl3.crl.com (George
> Herbert) wrote:
> > power plants are the cheapest ones, amorphous silicon cells, which run
> > around 10% efficient.
>
> Any idea on the efficiency and cost of solar thermal?
>

The concentrator/thermal collector efficiency is limited by radiation from
the thermal collector. Collectors do their best to resemble a black body
(material limited) of possibly 1200-1500C temperature. When I worked on
the solar-dynamic power system for Space Station, I recall that the
thermal collectors managed to limit re-radiation losses to 10-20%.

If you assume a backing cycle gas turbine with solar concentrators
replacing the combustors, the thermal efficiency's going to be a lot lower
than a gas-fired plant with turbine entry temperatures maybe 1000C lower,
so the thermal efficiency of the plant would be maybe 30-40%.

The end-to-end efficiency would be roughly 25-35% at best.

The cost of the backing cycle plant would be of the same order as a
current gas-fired plant (cheap). The collectors' cost would be driven by
the need to produce a high quality solar image inside the (small) aperture
into the thermal collector. The optics we proposed weren't cheap but that
was for space station. I have no feel for the cost of a terrestrial
system.


--
"Whatever happens will be for the worse and
therefore it is in our interest that
as little should happen as possible."

Paul F Austin
pau...@digital.net

George Herbert

unread,
Apr 16, 2000, 3:00:00 AM4/16/00
to
Paul F Austin <pau...@digital.net> wrote:

>"Samuel Paik" <pa...@webnexus.com> wrote:
>> gher...@crl3.crl.com (George Herbert) wrote:
>> > power plants are the cheapest ones, amorphous silicon cells, which run
>> > around 10% efficient.
>>
>> Any idea on the efficiency and cost of solar thermal?
>
>[...]

>The end-to-end efficiency would be roughly 25-35% at best.

My understanding is that you can do better than that, but not easily.
The advantage is that the mirror can be very very light and is
completely radiation resistant, unlike solar panels.

>The cost of the backing cycle plant would be of the same order as a
>current gas-fired plant (cheap). The collectors' cost would be driven by
>the need to produce a high quality solar image inside the (small) aperture
>into the thermal collector. The optics we proposed weren't cheap but that
>was for space station. I have no feel for the cost of a terrestrial
>system.

It's been done. The limiting cost is pointing the thing.
You have to aim it accurately at the sun, and/or use segmented
mirrors in an array each of which is seperately pointed, to focus
the sunlight on the small thermal collector. The mechanical and
electronic systems required for precision aim end up being fairly
expensive for ground application, all things considered. As I
pointed out earlier, land cost is among the smallest contributions
to overall system cost, and spending more land and using non pointed
amorphous silicon or other thin film solar cells is as far as has
been demonstrated so far much cheaper.


-george william herbert
gher...@crl.com


Paul F. Dietz

unread,
Apr 16, 2000, 3:00:00 AM4/16/00
to
George Herbert wrote:

> It's been done. The limiting cost is pointing the thing.
> You have to aim it accurately at the sun, and/or use segmented
> mirrors in an array each of which is seperately pointed, to focus
> the sunlight on the small thermal collector. The mechanical and
> electronic systems required for precision aim end up being fairly
> expensive for ground application, all things considered.

The other problem is that in many places, a good fraction
of the insolation is diffuse, scattered off clouds and
such. A high concentration system cannot collect this
light, while a flat plate collector can.

High-concentration system also can be used with PV cells,
since you can spend much more per square cm of cell.
Also, PV cell voltage increases with intensity (if
the cell is kept at a constant temperature); this is
a consequence of the diode equation.

Paul

Paul F Austin

unread,
Apr 16, 2000, 3:00:00 AM4/16/00
to

"George Herbert" <gher...@crl3.crl.com> wrote in message
news:8dcu20$f...@crl3.crl.com...

> Paul F Austin <pau...@digital.net> wrote:
> >"Samuel Paik" <pa...@webnexus.com> wrote:
> >> gher...@crl3.crl.com (George Herbert) wrote:
> >> > power plants are the cheapest ones, amorphous silicon cells, which
run
> >> > around 10% efficient.
> >>
> >> Any idea on the efficiency and cost of solar thermal?
> >
> >[...]
> >The end-to-end efficiency would be roughly 25-35% at best.
>
> My understanding is that you can do better than that, but not easily.
> The advantage is that the mirror can be very very light and is
> completely radiation resistant, unlike solar panels.

Yep. We delivered a 60m deployable mirror to Lewis Research Center in
about 1991. Unfortunately, solar-dynamic systems didn't make the cut for
Space Station.

Neil

unread,
Apr 16, 2000, 3:00:00 AM4/16/00
to
In rec.arts.sf.written Brett Evill <b.e...@nospam.tyndale.apana.org.au> wrote:

> A few years ago I attended a very interesting seminar given by Dr George
> Dupont-Roc, the head of Energy Futures for the Shell company. On grounds
> that seemed quite sound he predicted a proliferation of new economical
> power sources in the next thirty to fifty years, as the technology
> matures and unit costs drop. Solar, gasified biomass and quite a few
> others will, he predicted, join our current mix of coal, natural gas,
> oil, hydroelectric, and nuclear power sources. But although the existing
> technologies will lose market share, they will not be completely
> supplanted. The prospect for 2050 is that there will be eleven or twelve
> energy technologies each supplying 5% or more of global power
> requirements, each one concentrated in a niche dictated by geographical
> factors and the technical niceties of energy density and delivery mode.
<SNIP>
Excellent! My only dissapointment is that we have not given a bit of a
push to this process by taxing carbon more heavily. I say increase the
gas tax; lower the income tax.

> I think my notes on the seminar are still on the hard drive of my
> machine at work. I'll post them if I can find them and if anyone is
> interested.

Please do post it. I am sure a lot of people here would read it.


--

Neil

Brett Evill

unread,
Apr 17, 2000, 3:00:00 AM4/17/00
to
George Herbert wrote:

>
> Pete McCutchen <p.mcc...@worldnet.att.net> wrote:
> >gher...@crl3.crl.com (George Herbert) wrote:
> >>Right, best estimates are that current cells are about a factor
> >>of three too expensive for ground power, but there's a significant
> >>price drop curve in effect as production volume increases and
> >>as the technologies improve and mature, with expected crossover
> >>to net parity with current base load costs around 2006 if the
> >>curve stays constant and grid power costs stay about the same.
> >
> >Wow. I hadn't realized that it was that close to being economical.
>
> Yep, knocking on wood but it doesn't appear that far out.

A few years ago I attended a very interesting seminar given by Dr George


Dupont-Roc, the head of Energy Futures for the Shell company. On grounds
that seemed quite sound he predicted a proliferation of new economical
power sources in the next thirty to fifty years, as the technology
matures and unit costs drop. Solar, gasified biomass and quite a few
others will, he predicted, join our current mix of coal, natural gas,
oil, hydroelectric, and nuclear power sources. But although the existing
technologies will lose market share, they will not be completely
supplanted. The prospect for 2050 is that there will be eleven or twelve
energy technologies each supplying 5% or more of global power
requirements, each one concentrated in a niche dictated by geographical
factors and the technical niceties of energy density and delivery mode.

Dr Dupont-Roc suggested that although oil production will decline
substantially in that time, oil will not become scarce, because it will
be supplemented by other technologies in the large static power
generation task, so that adequate oil will still be available for use as
a vehicle fuel where needed.

I think my notes on the seminar are still on the hard drive of my
machine at work. I'll post them if I can find them and if anyone is
interested.

Regards,


Brett Evill

Sea Wasp

unread,
Apr 17, 2000, 3:00:00 AM4/17/00
to
Neil wrote:

> Excellent! My only dissapointment is that we have not given a bit of a
> push to this process by taxing carbon more heavily.

You carbon-based lifeforms want to tax yourselves more heavily?

--
Sea Wasp http://www.wizvax.net/seawasp/index.html
/^\
;;; _Morgantown: The Jason Wood Chronicles_, at
http://www.hyperbooks.com/catalog/20040.html

Brett Evill

unread,
Apr 18, 2000, 3:00:00 AM4/18/00
to
Here is the summary I wrote for my supervisor after Dr Dupont-Roc's seminar:

********************************************************
Franzi,

Today's seminar was very interesting. We were only shown the tip of the
iceberg, but there was plenty of depth where-ever anybody chose to sound. The
scenarios presented, although very comforting in their conclusions, seem to be
reasonably conservative in their assumptions. The weakest point would seem to
be that developing nations were assumed to fuel their future progress by
adopting (as they become commercially available) what are now emerging
technologies, with technology being transferred by direct investment.
Institutional impediments to this process could result in developing nations
relying rather upon low-tech, resource-intensive sources of energy.

We were treated to an overview of the history of energy sources in the last
century, with transport fuels as a central example. In the scenarios that
followed, the emerging energy sources were assumed to develop as coal, oil,
and gas have in the past. Wind-power, gas turbines fueled by gasified biomass,
photovoltaics, hydroelectricity, geothermal power, and a surprise (perhaps
fusion) were projected to become cost-effective in succession, without it
being assumed that oil prices would rise.

In the scenarios, population growth and development were assumed to continue
current trends up to 2050 (the horizon of projection), with population
reaching 11.2 billion and global average per-capita GDP rising to about the
current Italian level. One scenario assumed that the energy-intensity of
production in various countries would either continue current trends or
follow a path similar to that followed by the developed countries as they
industrialised, as appropriate. This was called the 'Continued Growth'
scenario. The other, more optimistic, assumed that technological improvements
and the growth of information and service industries would allow the
energy-intensity of production to continue to decline at 2% per annum. This
was called the "De-materialisation" scenario.

The projections depicted a great increase in the diversity of energy sources,
with ten primary sources each having 5-20% of the market by 2050. Global
energy consumption was high and climbing fast at 2050 in both scenarios. As an
aside, CO2 emissions had been projected. These peaked around 2010 or 2020, and
then began to decline steadily. According to the presenter, his
De-materialisation scenario would stabilise the CO2 level at about twice the
pre-industrial (I think, might have been current) level, and his Continued
Growth scenario would stabilise it at around three times. He expressed great
skepticism about the IPCC projections, which he has apparently analysed in
some detail, despite obstruction by the IPCC people (he had to get a lot of
their unpublished data by the back door).

I asked about the energy investment in generating capacity per unit of power
generated, and discovered that it was assumed to be fixed in the Continued
Growth scenario and to decline at 2% per annum in the De-materialisation
scenario.

Most of the emerging energy sources are either fixed-output (eg. biomass,
solar, hydroelectricity) or fixed stock (geothermal), so cannot support
indefinite growth. On the other hand, they can easily support projected growth
to the limits of these scenarios. Back-of-envelope calculations suggest that
when photovoltaics become economical, France (for instance) would be able to
meet twice its energy requirements with an area of collectors equal to what it
now dedicates to non-urban roads.

Where-ever the assumptions underlying the projections of future energy demand
and supply were questioned, they seemed plausible, even, sometimes,
conservative. This work seems sound, and important. We must keep an eye on it.

The head sarang is Georges Dupont-Roc, who gave this seminar.

Regards,


Brett.
*******************************************************

--
Brett Evill
(The opinions expressed above are not those of the Bureau of Transport
Economics, the Federal Department of Transport and Regional Services, or the
Australian Commonwealth Government.)


cfr...@my-deja.com

unread,
Apr 19, 2000, 3:00:00 AM4/19/00
to
In article <8dbpdr$b...@crl3.crl.com>,
gher...@crl3.crl.com (George Herbert) wrote:

Ref solar power:-

>
> Two things it can't do is completely replace existing fossil
> fuel and provide 24x7 power. Nighttime base load is significant

Nightime baseload is 55% of daytime baseload (in north America).

> and cannot be addressed by solar power (except perhaps with pumped
> storage, which is geographically difficult in most areas... the cost

Pumped storage is environmentally damaging even where it is feasible.

> your night loads from places the sun is up. Solar power satellites
> might also be cost effective for nighttime power loads in 20 or
> more years, depending on the state of space development, but the
> daytime load (and by far most of the kWhr used over the course of
> a full day cycle) will most likely be most cheaply provided by
> ground solar.
>

Well, night time baseload is only 45% lower than daytime. In even in
nominal daytime, there are long periods of outages caused by normal
cloudy days, so solar power for daytime baseload is very unreliable.
In most locations you cannot predict from one minute to the next how
much power will be delivered.

A better way to think of it would be a solar power satellite giving the
steady 24 hour baseload, and the terrestrial solar power handles the
daytime spike (as best it can). There will still need to be some
storage in daytime to handle the clouds passing between the sun and the
collector.

cfr...@my-deja.com

unread,
Apr 19, 2000, 3:00:00 AM4/19/00
to
In article <8dbpdr$b...@crl3.crl.com>,
gher...@crl3.crl.com (George Herbert) wrote:
> Pete McCutchen <p.mcc...@worldnet.att.net> wrote:
> >gher...@crl3.crl.com (George Herbert) wrote:
> your night loads from places the sun is up. Solar power satellites
> might also be cost effective for nighttime power loads in 20 or
> more years, depending on the state of space development, but the
> daytime load (and by far most of the kWhr used over the course of
> a full day cycle) will most likely be most cheaply provided by
> ground solar.
>

SPS will also have a major role in daytime power, that is....

As clouds move across the face of the Earth, masking out terrestrial
collectors on an unpredictable basis, SPS can instantly switch power
beams from place to place to smooth out local short term variations in
the terrestrial solar collector output.

Switching power beams is a light misnomer, the beams would have their
power increased or decreased over a range of power levels, it is not
simply an on/off mode.

The only alternative to this would be either long distance power
transmission or local power storage via batteries or whatever.

Brett Evill

unread,
Apr 20, 2000, 3:00:00 AM4/20/00
to
cfr...@my-deja.com wrote:

> A better way to think of it would be a solar power satellite giving the
> steady 24 hour baseload, and the terrestrial solar power handles the
> daytime spike (as best it can). There will still need to be some
> storage in daytime to handle the clouds passing between the sun and the
> collector.

If the solar collectors are hooked up into a continent-spanning power
grid the variation in supply due to cloud will be very small, since
cloud is mostly a local phenomenon.

Solar energy can be stored to supply the nighttime load by electrolysing
water by day and feeding the hydrogen and oxygen through a power cell by
night. Pumped storage is by no means the only choice.

And how do you plan to get power generated in a satellite down from
orbit? A beanstalk? Microwaves? Is either of those technologies
currently practicable? Will either of them be safe? Will either one be
without adverse environmental impacts?

Regards,


Brett Evill

Brett Evill

unread,
Apr 20, 2000, 3:00:00 AM4/20/00
to
cfr...@my-deja.com wrote:
>
> SPS will also have a major role in daytime power, that is....
>
> As clouds move across the face of the Earth, masking out terrestrial
> collectors on an unpredictable basis, SPS can instantly switch power
> beams from place to place to smooth out local short term variations in
> the terrestrial solar collector output.
>
> Switching power beams is a light misnomer, the beams would have their
> power increased or decreased over a range of power levels, it is not
> simply an on/off mode.
>
> The only alternative to this would be either long distance power
> transmission or local power storage via batteries or whatever.

Not so. The surface solar collectors can be used to generate hydrogen by
electrolysis of water (the oxygen can safely be vented). The hydrogen
can then be mixed with 1% CO2 (to stop it from adsorbing to steel), and
pumped all around the continent in steel pipes (pumping hydrogen is very
cheap because of its low molecular mass). Some of the hydrogen would
have to be burned to run the compressors along the line, but only 1% per
thousand kilometres.

In each city or city district the hydrogen can be stored in a gasometer
(a lot of cities already have this infrastructure) to provide steady
supplies through daily variations of supply and of demand for power. The
hydrogen can either be piped to households, each with its own
refrigerator-sized fuel cell, or used to generate electricity (in large
power cells or turbine-powered generators) on a neighbourhood or
district scale for domestic distribution.

Regards,


Brett Evill

cfr...@my-deja.com

unread,
Apr 20, 2000, 3:00:00 AM4/20/00
to
In article <38FE9C...@nospam.tyndale.apana.org.au>,

Brett Evill <b.e...@nospam.tyndale.apana.org.au> wrote:
> cfr...@my-deja.com wrote:
>
> > A better way to think of it would be a solar power satellite giving
the
> > steady 24 hour baseload, and the terrestrial solar power handles the
> > daytime spike (as best it can). There will still need to be some
> > storage in daytime to handle the clouds passing between the sun and
the
> > collector.
>
> If the solar collectors are hooked up into a continent-spanning power
> grid the variation in supply due to cloud will be very small, since
> cloud is mostly a local phenomenon.
>
> Solar energy can be stored to supply the nighttime load by
electrolysing
> water by day and feeding the hydrogen and oxygen through a power cell
by
> night. Pumped storage is by no means the only choice.
>

Indeed, it was George Herbert who confined himself to pumped storage,
not I.

The problem with ALL energy storage systems is that they far exceed the
cost of the solar collectors and dominate the overall system cost.

> And how do you plan to get power generated in a satellite down from
> orbit? A beanstalk? Microwaves? Is either of those technologies

Microwaves, beanstalks are not within the current state of the art.

> currently practicable? Will either of them be safe? Will either one be
> without adverse environmental impacts?
>

Microwaves have a lower environmental impact than any of the
alternatives, for example they do not contribute to the greenhouse
effect.

As for safety:

The only known health effects of microwaves are due to thermal
absorption by water, and only certain frequencies get absorbed at all.

The SPS beam would have a peak intensity less than that of sunlight,
i.e. about 1 KW/sq metre. Because microwaves can be converted at about
98% efficiency, versus 20% or so for the best solar cell, it will
deliver a lot more power to the grid per unit area (George Herbert
argues that lavish use of land area is not a problem in any event).

The frequecies used will not be absorbed by water, so will have no
effects on organimsms nor on the atmosphere.

Microwaves have been in our environment for about 50 years, so there is
quite a lot of safety data.

cfr...@my-deja.com

unread,
Apr 20, 2000, 3:00:00 AM4/20/00
to
In article <38FE9F...@nospam.tyndale.apana.org.au>,
> > SPS will also have a major role in daytime power, that is....
> >
> > As clouds move across the face of the Earth, masking out terrestrial
> > collectors on an unpredictable basis, SPS can instantly switch power
> > beams from place to place to smooth out local short term variations
in
> > the terrestrial solar collector output.
> >
> > Switching power beams is a light misnomer, the beams would have
their
> > power increased or decreased over a range of power levels, it is not
> > simply an on/off mode.
> >
> > The only alternative to this would be either long distance power
> > transmission or local power storage via batteries or whatever.
>
> Not so. The surface solar collectors can be used to generate hydrogen
by electrolysis

This is simply another method of storage, within the intent of my
remark.

The cost of your hydrogren based electoysis system will be high, and
will dominate the overall system cost, higher than the cost of the
solar collectors.

Tom Breton

unread,
Apr 20, 2000, 3:00:00 AM4/20/00
to
Brett Evill <b.e...@nospam.tyndale.apana.org.au> writes:

> cfr...@my-deja.com wrote:
>
> > A better way to think of it would be a solar power satellite giving the
> > steady 24 hour baseload, and the terrestrial solar power handles the
> > daytime spike (as best it can). There will still need to be some
> > storage in daytime to handle the clouds passing between the sun and the
> > collector.
>
> If the solar collectors are hooked up into a continent-spanning power
> grid the variation in supply due to cloud will be very small, since
> cloud is mostly a local phenomenon.

Ooh, you've got to watch the weather report more often. It's very
common to see a good fraction of North America obscured by the same
weather pattern. Or unobscured by the same sunny weather pattern, but
that's not reported as news.


> Solar energy can be stored to supply the nighttime load by electrolysing
> water by day and feeding the hydrogen and oxygen through a power cell by
> night. Pumped storage is by no means the only choice.
>

> And how do you plan to get power generated in a satellite down from
> orbit? A beanstalk? Microwaves? Is either of those technologies

> currently practicable?

Microwaves. Rectennas are decades old.

> Will either of them be safe?

Microwaves.

> Will either one be
> without adverse environmental impacts?

Microwaves. I don't mean to be a big microwave booster, but these
questions about microwave power have all come up before and been
answered by people more knowledgeable than I.

--
Tom Breton, http://world.std.com/~tob
Not using "gh" since 1997. http://world.std.com/~tob/ugh-free.html

cfr...@my-deja.com

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to
In article <38FAEF...@wizvax.net>,

sea...@wizvax.net wrote:
> Neil wrote:
>
> > Excellent! My only dissapointment is that we have not given a bit
of a
> > push to this process by taxing carbon more heavily.
>
> You carbon-based lifeforms want to tax yourselves more heavily?
>

This is the central problem.

To put it another way, how much extra are we willing to pay to avert
global warming ?

Brett Evill

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to
Tom Breton wrote:

> > If the solar collectors are hooked up into a continent-spanning power
> > grid the variation in supply due to cloud will be very small, since
> > cloud is mostly a local phenomenon.
>
> Ooh, you've got to watch the weather report more often. It's very
> common to see a good fraction of North America obscured by the same
> weather pattern. Or unobscured by the same sunny weather pattern, but
> that's not reported as news.

We don't have that trouble here. Want us to ship you some hydrogen?

And I must say that I find what yousay surprising. Mexico is less sunny
than I thought.

Regards,


Brett Evill

Brett Evill

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to
cfr...@my-deja.com wrote:
>
> In article <38FE9F...@nospam.tyndale.apana.org.au>,
> Brett Evill <b.e...@nospam.tyndale.apana.org.au> wrote:
> > cfr...@my-deja.com wrote:
> > >
> > > The only alternative to this would be either long distance power
> > > transmission or local power storage via batteries or whatever.
> >
> > Not so. The surface solar collectors can be used to generate hydrogen
> by electrolysis
>
> This is simply another method of storage, within the intent of my
> remark.

Okay. I misunderstood your use of the word 'power'.

> The cost of your hydrogren based electoysis system will be high, and
> will dominate the overall system cost, higher than the cost of the
> solar collectors.

I must say that I find that surprising. Do you have figures?

Regards,


Brett Evill

Brett Evill

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to
cfr...@my-deja.com wrote:
>
> In article <38FE9C...@nospam.tyndale.apana.org.au>,

> > Solar energy can be stored to supply the nighttime load by
> electrolysing
> > water by day and feeding the hydrogen and oxygen through a power cell
> by
> > night. Pumped storage is by no means the only choice.
> >
>

> Indeed, it was George Herbert who confined himself to pumped storage,
> not I.
>
> The problem with ALL energy storage systems is that they far exceed the
> cost of the solar collectors and dominate the overall system cost.

I am surprised to read that that is the case. I had no idea that
gasometers were so expensive. But in any case, most of those cities that
have ever had natural gas or town gas supplies still have gasometers, so
this expensive storage infrastructure already exists.

Regards,


Brett Evill

Riboflavin

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to
Brett Evill wrote in message <38FFCD...@nospam.tyndale.apana.org.au>...


Take a look at http://www.wral-tv.com/weather/genesis/ for some weather maps
(it's actually a local station for me that I usually use for tracking
hurricanes, but they do have a US map, which even shows some of Mexico).
Even at the moment I'm writing this, there are some rather large cloud
formations in the US. They're not everywhere, but I'm not sure how easy the
continuously generated hydrogen is to ship around, and a nationwide power
grid would lose huge amounts of power over the lines (this is already a
problem in the more spread out western states, where brownouts and outages
are relatively frequent and rates are higher due to transmission losses).
--
Kevin Allegood ribotr...@mindspring.pants.com
Remove the pants from my email address to reply
"I once met a person with a billion point IQ. Her father taught
politics and she was a practice subject for people studying
unsupported anecdotes." -Jim Balter

Charles F. Radley - CSQE -Oregon L5

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to
>> The cost of your hydrogren based electoysis system will be high, and
>> will dominate the overall system cost, higher than the cost of the
>> solar collectors.
>
>I must say that I find that surprising. Do you have figures?
>

Fair question, I do not have figures handy, I find the US Dept of Energy web
site has a lot of good info. I willl try to put something together over the
next few days.

It seems pretty obvious to me actually.

The up-front capital cost of the infrastructure to safely store and transport
hydrogen is quite high.

The costs will depend reatly on the amount of local storage, i.e. how large a
buffer against solar outages do you anticipate.

Hydrogen is very difficult to contain, it is almost like Helium, it escapes and
diffuses through containers which are nominally hermetically sealed.

Old style gasometers and pipelines will not be adequate, a higher level of
sealing will be needed.
=====
The main question of course is whether such a system could econmically compete
with space solar power.

The answer is by no means obvious.

Delete the not from the end of my email address.

URL: http://members.aol.com/cfrjlr

Software Quality Engineer (former Rocket Scientist)


Charles F. Radley - CSQE -Oregon L5

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to
>case, most of those cities that
>have ever had natural gas or town gas supplies still have gasometers, so
>this expensive storage infrastructure already exists.
>

Not.

My home town in the UK used to have gasometers during the times of Coal Gas.
When they switched to Natural Gas the gasometers were dismantled. The gas is
piped in directly, and the flow rate adjusted at source as necessary.

There are very few gasometers in the USA, I know of one in Long Beach,
California. It is next to an oil refinery. I think there are still one or two
in the Houston area.

In any case, gasometers and pipes to transport methane are inadequate for
transporting hydrogen, the leakage rates will be too high.

=========

And as I explained before, the main energy growth is in the third world, where
there is little infrastructure of any kind.

Cambias

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to
In article <8dnraa$cgj$1...@nnrp1.deja.com>, cfr...@my-deja.com wrote:

> In article <38FE9F...@nospam.tyndale.apana.org.au>,


> Brett Evill <b.e...@nospam.tyndale.apana.org.au> wrote:
> > cfr...@my-deja.com wrote:
> > >

> > > SPS will also have a major role in daytime power, that is....
> > >
> > > As clouds move across the face of the Earth, masking out terrestrial
> > > collectors on an unpredictable basis, SPS can instantly switch power
> > > beams from place to place to smooth out local short term variations
> in
> > > the terrestrial solar collector output.
> > >
> > > Switching power beams is a light misnomer, the beams would have
> their
> > > power increased or decreased over a range of power levels, it is not
> > > simply an on/off mode.
> > >

> > > The only alternative to this would be either long distance power
> > > transmission or local power storage via batteries or whatever.
> >
> > Not so. The surface solar collectors can be used to generate hydrogen
> by electrolysis
>
> This is simply another method of storage, within the intent of my
> remark.
>

> The cost of your hydrogren based electoysis system will be high, and
> will dominate the overall system cost, higher than the cost of the
> solar collectors.
>

And it should be noted that water vapor -- which is what fuel cells emit
-- is an even better greenhouse gas than carbon dioxide.

Cambias

Paul F. Dietz

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to
Cambias wrote:

> And it should be noted that water vapor -- which is what fuel cells emit
> -- is an even better greenhouse gas than carbon dioxide.

And it should be noted that this is a rather blatantly
idiotic canard. CO2 emissions tend to increase
atmospheric CO2 levels for decades or centuries, while
water vapor emissions have no long-lasting effects as
the water precipitates out.

Paul

Cambias

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to
In article <3900600A...@interaccess.com>, "Paul F. Dietz"
<di...@interaccess.com> wrote:

"Canard?" I'm insulting water?

It's not blatantly idiotic because we don't know if really extensive water
vapor emissions will precipitate out so easily. And it's also worth
pointing out that even nice clean hydrogen fuel does involve some risks.
Everything involves a tradeoff; there are no perfect answers.

Cambias

Paul F. Dietz

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to
Cambias wrote:

> "Canard?" I'm insulting water?

Canard: a false or unfounded report or story.


> It's not blatantly idiotic because we don't know if really extensive water
> vapor emissions will precipitate out so easily.

Look, this is all painfully obvious if you bother
to think about it. Do please try to do that.

Paul

Neil

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to
In rec.arts.sf.written cfr...@my-deja.com wrote:

> This is the central problem.

> To put it another way, how much extra are we willing to pay to avert
> global warming ?

If we increased consumption taxes we could decrease income taxes.


--

Neil

pervect

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to

"Paul F. Dietz" <di...@interaccess.com> wrote in message
news:39007209...@interaccess.com...

Why think when you have the chance to repeat pro-CO2 propaganda, courtesy of
your local coal company? :-)

I think it's interesting the way things tend to polarize in our society - I
saw a program on global warming that brought this to mind. The coal company
executives were sponsoring spin on how CO2 was good for plants. The greens
were pursuing pie-in-the sky ideas about renewable energy resources for 100%
of our energy needs. (The program was pretty good about pointing out that
we might not be able to spare 30% of our land area for more biomass, wind,
or solar farms - and that plants normally released the CO2 they absorbed
during life when they died and decayed.)

It seems pretty obvious to me that if we are really serious about reducing
greenhouse gasses, with our current technology we will have to start relying
more on nuclear fission plants. This isn't something I'm really wild
about - the nuclear industry is just as bad as everyone else, they've got
people claiming that ionizing radiation is "natural" and "good for you"
(radiation hormonesis).


George William Herbert

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to
<cfr...@my-deja.com> wrote:
> gher...@crl3.crl.com (George Herbert) wrote:
>Ref solar power:-
>> Two things it can't do is completely replace existing fossil
>> fuel and provide 24x7 power. Nighttime base load is significant
>
>Nightime baseload is 55% of daytime baseload (in north America).

PG&E values for California (which I have in detail; nationwide figures
are not available in depth online, and I haven't found good ones
offline so far) are nighttime baseload of 35-38%, not 55%.

>[...]


>Well, night time baseload is only 45% lower than daytime. In even in
>nominal daytime, there are long periods of outages caused by normal
>cloudy days, so solar power for daytime baseload is very unreliable.
>In most locations you cannot predict from one minute to the next how
>much power will be delivered.

You can much better if you geographically average. Over a given
square meter it's uncertain; over a square kilometer (except right
near mountain crests and other cloud nucleating regions) it varies
slowly and over a hundred 1-sq-km regions scattered around the
southwest it's statistically even better.

You do need alternate generating sources and enough geographical
area to statistically even things out. The key here is that you
can affordably get rid of *most* of the fossil fuel usage and
have fast start nautral gas gas turbines for the statistical
transients which will happen, or other alternate sources or
storage facilities.


-george william herbert
gher...@retro.com


George William Herbert

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to
<cfr...@my-deja.com> wrote:

> Brett Evill <b.e...@nospam.tyndale.apana.org.au> wrote:
>> If the solar collectors are hooked up into a continent-spanning power
>> grid the variation in supply due to cloud will be very small, since
>> cloud is mostly a local phenomenon.
>>
>> Solar energy can be stored to supply the nighttime load by electrolysing
>> water by day and feeding the hydrogen and oxygen through a power cell by
>> night. Pumped storage is by no means the only choice.
>
>Indeed, it was George Herbert who confined himself to pumped storage,
>not I.

I didn't feel like giving the 30 solution long list in the article
in question... I am fully aware of, and support, the various alternative
technologies including electrolyzed water+fuel cells or turbines,
battery banks, pumped thermal storage, large flywheels, etc. etc.
Pumped water storage is the cheapest and easiest to impliment
right now, but would not necessarily be the right long term solution.
I look at 2005 solutions a lot for what's likely to happen when the
amorphous cell technologies hit the price parity with current grid
power point, but there's obviously a lot more going on for longer
down the pipeline than that. Even my favorites for short term are
just that; the situation, if examined in detail, has a lot of
alternatives which are within a reasonably close cost band and
any of them might turn out optimal.

>[...]


>The SPS beam would have a peak intensity less than that of sunlight,
>i.e. about 1 KW/sq metre. Because microwaves can be converted at about
>98% efficiency, versus 20% or so for the best solar cell, it will
>deliver a lot more power to the grid per unit area (George Herbert
>argues that lavish use of land area is not a problem in any event).

...Primarily because the total land area usage in most countries
for peak world population power requirements at first world
per-capita power ranges is pretty small. The US for example
is talking about 1% of total continental US surface area or so
assuming reasonable endstate population and per-capita power;
I think 350 million and about 1.5 times current per-capita were
my planning assumption, and we use around 20% for farming now.
If it were 10% I think it would be a problem people would yell
about, but it's not. Lavish in terms of total count is one thing,
but in relative terms (total space used by human activities
including urban, suburban, farming, other resources, etc)
it's not that much.

I have not yet identified any country except Bangladesh which
cannot possibly support local solar generation in the long term,
though India is a difficult case. Bangladesh would have to
import power anyways, be it fossil or nuclear fuels or whatnot,
so importing power via long transmission lines is not fundamentally
worse than the alternatives. India may want to buy power from
desert countries in the near east and africa, as might Bangladesh.

I will end with my usual disclaimer; my analysies show that in
general Solar is a good alternative for both near (5 year) and long
term clean power generation, but I in no way wish to insult or degrade
the other alternatives. There are quite a few possible solutions
which appear both feasible and affordable; I personally think ground
flat panel Solar is the most feasible and affordable but remain
interested in alternatives and am willing to sit corrected if my
assumptions prove wrong or another alternative is more cost effective.


-george william herbert
gher...@retro.com


Dan Holdsworth

unread,
Apr 21, 2000, 3:00:00 AM4/21/00
to
On Fri, 21 Apr 2000 10:59:51 -0400, Cambias
<cam...@SPAHMTRAP.heliograph.com>
was popularly supposed to have said:

>In article <3900600A...@interaccess.com>, "Paul F. Dietz"
><di...@interaccess.com> wrote:
>
>> Cambias wrote:
>>
>> > And it should be noted that water vapor -- which is what fuel cells emit
>> > -- is an even better greenhouse gas than carbon dioxide.
>>
>> And it should be noted that this is a rather blatantly
>> idiotic canard. CO2 emissions tend to increase
>> atmospheric CO2 levels for decades or centuries, while
>> water vapor emissions have no long-lasting effects as
>> the water precipitates out.
>>

>"Canard?" I'm insulting water?
>

>It's not blatantly idiotic because we don't know if really extensive water

>vapor emissions will precipitate out so easily. And it's also worth
>pointing out that even nice clean hydrogen fuel does involve some risks.
>Everything involves a tradeoff; there are no perfect answers.

Err, yes we do know what happens to large amounts of water vapour.

Go look up what a "Monsoon" is, please.

--
Dan Holdsworth PhD da...@supanet.com
By caffeine alone I set my mind in motion, By the beans of Java
do thoughts acquire speed, hands acquire shaking, the shaking
becomes a warning, By caffeine alone do I set my mind in motion

Brett Evill

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
Riboflavin wrote:
>
> They're not everywhere, but I'm not sure how easy the
> continuously generated hydrogen is to ship around

It leaks a bit faster than natural gas. But it's still easy to pipe, and
I can't think of any reason why those CNG tankers shouldn't carry it.

>and a nationwide power
> grid would lose huge amounts of power over the lines (this is already a
> problem in the more spread out western states, where brownouts and outages
> are relatively frequent and rates are higher due to transmission losses).

We have a national power grid in Australia. It doesn't, in fact, cover
the whole continent, but it does stretch from Adelaide the Sydney and
from Melbourne to southern and perhaps central Queensland. Losses aren't
crippling, or even particularly expensive.

Regards,


Brett Evill

Brett Evill

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
Charles F. Radley - CSQE -Oregon L5 wrote:
>
> There are very few gasometers in the USA, I know of one in Long Beach,
> California. It is next to an oil refinery. I think there are still one or two
> in the Houston area.
>
> In any case, gasometers and pipes to transport methane are inadequate for
> transporting hydrogen, the leakage rates will be too high.

Some of my colleagues looked into this issue while we were working on
the greenhouse gas abatement study. What you say may be true for the
urban distribution pipes. But the engineers assured us that it would be
practicable to pump hydrogen along the existing long-distance gas
pipelines build for natural gas, provided that 1% CO2 was included to
combat the tendency of hydrogen to adsorb to the steel.

But what if we did have to replace the pipelines? To build them was
economic for piping methane and ethane from a gas field. Why would it
not be economic for piping hydrogen from a photoelectric electrolysis
plant?

Regards,


Brett Evill

Brett Evill

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
Charles F. Radley - CSQE -Oregon L5 wrote:
>
> It seems pretty obvious to me actually.
>
> The up-front capital cost of the infrastructure to safely store and transport
> hydrogen is quite high.

So is the cost of boosting hundred of square kilometres of photoelectric
material, microwave generating and focussing equipment etc. into orbit.
If these facilities are to be below geostationary orbit, the beaming
equipment will have to be orientable, and that will mean that the
facilities will have to be continually supplied with consumables. If
they are to be in geostationary orbit the placement cost will be all the
higher.

What does it cost to place a square kilometre of photocells with
supports and cabling in geostationary orbit?

> Hydrogen is very difficult to contain, it is almost like Helium, it escapes and
> diffuses through containers which are nominally hermetically sealed.

I would have guessed that it was worse than helium. Diffusion rates
depend inversely on molecular mass if I recall correctly.

> Old style gasometers and pipelines will not be adequate, a higher level of
> sealing will be needed.

I'm not sure about the gasometers, and will concede that they may need
to be replaced. But as I said in another post, the advice that the
engineers gave my colleagues when they were studying means of reducing
Australia's GHG emissions was that our modern loss-distance gas
pipelines are adequate to carrying hydrogen, provided that the
compressors and regulators were replaced with more suitable designs, and
provided that a little CO2 was included in the hydrogen (something about
adsorbed hydrogen making components brittle.

> The main question of course is whether such a system could econmically compete
> with space solar power.
>
> The answer is by no means obvious.

Quite true.

Perhaps the issue is one of timeframe. I am thinking to a system that
could be delivering power on an commercial scale within ten to fifteen
years. When we have colonies in space and on the Moon the cost of
orbital power stations might not be so high.

Regards,


Brett Evill

Brett Evill

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
Cambias wrote:
>
> And it should be noted that water vapor -- which is what fuel cells emit
> -- is an even better greenhouse gas than carbon dioxide.

No it isn't. The greenhouse warming potential of a gas depends not only
on its opacity to IR, but also on its propensity to accumulate in the
atmosphere, and also on the pre-existent opacity of the atmosphere in
the wavelengths it blocks.

If you emit CO2 into the atmosphere its average life in the atmosphere
is ninety years. So emitted CO2 will accumulate. Also, the atmosphere is
far from opaque in some of the wavelengths that CO2 blocks. Accumulating
CO2 will make the atmosphere more IR-opaque.

Water vapour does not accumulate in the atmosphere. It is a vapour, not
a gas, it exists in equilibrium with open bodies of water. Emit water
vapour into the atmosphere and it will condense out as rain, snow or
dew, not accumulate in the atmosphere. Further, the pre-existent water
vapour in the atmosphere is already sufficient to make the atmosphere
completely opaque in the wavelengths that water vapour blocks.

It *is* true that most of the natural greenhouse warming that keeps this
planet habitably warm is provided by water vapour. And it is true that,
by themselves, water vapour is a more potent greenhouse gas than CO2.
But water vapour emissions from burning hydrogen as fuel cannot
significantly increase the concentration of water vapour in the
atmosphere, and even if they did, it wouldn't cause extra greenhouse
warming.

Regards,


Brett Evill

Brett Evill

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
pervect wrote:
>
> (The program was pretty good about pointing out that
> we might not be able to spare 30% of our land area for more biomass, wind,
> or solar farms - and that plants normally released the CO2 they absorbed
> during life when they died and decayed.)

30%?

I once saw an estimate by the head of Future Energy Research (Dr. George
Dupont-Roc) for Shell International (an oil company) That France could
generate all the power it currently needs using less land than it has
devoted to non-urban roads. That's a lot less than 30% of the
countryside.

By I agree with you about fission. It has dangers and it causes
pollution, and therefore it kills people. But estimates indicate that
the nuclear fuel cycle kills an order of magnitude fewer people per unit
energy supplied than the coal power cycle. I haven't seen figures for
oil, but I'm far from happy about the number of oil spills at sea we
currently tolerate.

Regards,


Brett Evill

Brett Evill

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
cfr...@my-deja.com wrote:
>
> In article <38FAEF...@wizvax.net>,
> sea...@wizvax.net wrote:
> > Neil wrote:
> >
> > > Excellent! My only dissapointment is that we have not given a bit
> of a
> > > push to this process by taxing carbon more heavily.
> >
> > You carbon-based lifeforms want to tax yourselves more heavily?
> >
>
> This is the central problem.
>
> To put it another way, how much extra are we willing to pay to avert
> global warming ?

It's a very interesting question. I was on a research team that did
cost-effectiveness studies for a wide range of abatement measures in
transport. (Other teams did similar studies of possibilities in
industry, power generation, waste disposal, and land-use change. The
combined program was designed and times to inform our government for the
Kyoto Conference) We discovered a number of 'no-regrets' measures:
things that we could do that would *pay us* for reducing or GHG
emissions. I was therefore rather disappointed when the official
Australian position at Kyoto was that because we mine coal and have a
large transport task, we refused to abate emissions even when it was in
our own interest to do so.

The Germans and the Norwegians, on the other hand, are making great
progress already. German, for example, has achieved a 20% cut in
emissions, well ahead of schedule.

Regards,


Brett Evill

cfr...@my-deja.com

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
In article <39007209...@interaccess.com>,

"Paul F. Dietz" <di...@interaccess.com> wrote:
> Cambias wrote:
>
> > "Canard?" I'm insulting water?
>
> Canard: a false or unfounded report or story.
>
> > It's not blatantly idiotic because we don't know if really
extensive water
> > vapor emissions will precipitate out so easily.
>
> Look, this is all painfully obvious if you bother
> to think about it. Do please try to do that.
>
> Paul
>


Paul,

We have exchanged posting much in the past so you know where I am
coming from.

Water vapor will precipitate out just fine of course.
But I still have a minor concern
that depending on the locations of the emitter, local increase in cloud
cover could be caused as a result of the increased humidity around the
H2O emitter. This will not be a problem in most climates zones.

In practice we have plenty of H2O emitters already, as well as emitting
CO2, most power stations, factories, motor vehicles and aircraft emit
vast quantities of H2O into the atmosphere, and there seems to be
little measurable increase in cloud cover.

cfr...@my-deja.com

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
In article <cambias-2104...@d7b143.dialup.cornell.edu>,
cam...@SPAHMTRAP.heliograph.com (Cambias) wrote:
> In article <3900600A...@interaccess.com>, "Paul F. Dietz"
> <di...@interaccess.com> wrote:

>
> > Cambias wrote:
> >
> > > And it should be noted that water vapor -- which is what fuel
cells emit
> > > -- is an even better greenhouse gas than carbon dioxide.
> >
> > And it should be noted that this is a rather blatantly
> > idiotic canard. CO2 emissions tend to increase
> > atmospheric CO2 levels for decades or centuries, while
> > water vapor emissions have no long-lasting effects as
> > the water precipitates out.
> >
> "Canard?" I'm insulting water?
>
> It's not blatantly idiotic because we don't know if really extensive
water
> vapor emissions will precipitate out so easily. And it's also worth

Actually we do, billions of tons of water vapor are released to the
atmosphere right now by the very same sources which are emitting CO2.
The impact on the climate/environment of these massive H2O emissions
is negligible, compared to the CO2 emissions.

That is power stations, cars, aircraft, factories.

> pointing out that even nice clean hydrogen fuel does involve some
risks.
> Everything involves a tradeoff; there are no perfect answers.
>

Indeed, a hydrogen based fuel system represents a lower risk than a
carbon based fuel system.

We already have the data to show this.

cfr...@my-deja.com

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
In article <390121...@nospam.tyndale.apana.org.au>,
Brett Evill <b.e...@nospam.tyndale.apana.org.au> wrote:

> pervect wrote:
> >
> By I agree with you about fission. It has dangers and it causes
> pollution, and therefore it kills people. But estimates indicate that
> the nuclear fuel cycle kills an order of magnitude fewer people per
unit
> energy supplied than the coal power cycle. I haven't seen figures for
> oil, but I'm far from happy about the number of oil spills at sea we
> currently tolerate.
>

By comparison, what do you think of the safety or health risks of
microwave power beams ( at 1 KW/square meter) ?

cfr...@my-deja.com

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
In article <8dqrpt$i6$1...@gw.retro.com>,

gher...@gw.retro.com (George William Herbert) wrote:
> <cfr...@my-deja.com> wrote:
> > gher...@crl3.crl.com (George Herbert) wrote:
> >Ref solar power:-
> >> Two things it can't do is completely replace existing fossil
> >> fuel and provide 24x7 power. Nighttime base load is significant
> >
> >Nightime baseload is 55% of daytime baseload (in north America).
>
> PG&E values for California (which I have in detail; nationwide figures
> are not available in depth online, and I haven't found good ones
> offline so far) are nighttime baseload of 35-38%, not 55%.
>

There arte certainly regional variaitons.

55% was quoted on the recent PBS 2-hour special on global warming as a
national average.

> >[...]
> >Well, night time baseload is only 45% lower than daytime. In even in
> >nominal daytime, there are long periods of outages caused by normal
> >cloudy days, so solar power for daytime baseload is very unreliable.
> >In most locations you cannot predict from one minute to the next how
> >much power will be delivered.
>
> You can much better if you geographically average. Over a given
> square meter it's uncertain; over a square kilometer (except right
> near mountain crests and other cloud nucleating regions) it varies
> slowly and over a hundred 1-sq-km regions scattered around the
> southwest it's statistically even better.
>

Yes, as you said before, we need expensive inter-regional trnamissions
grids, which will dominate the system cost.

Either that, or storage which will dominate the system cost.


> You do need alternate generating sources and enough geographical
> area to statistically even things out. The key here is that you
> can affordably get rid of *most* of the fossil fuel usage and
> have fast start nautral gas gas turbines for the statistical
> transients which will happen, or other alternate sources or
> storage facilities.
>

Yes, and these things will dominate the system cost.

To the extent that power beamed from space begins to look attractive.

Paul F. Dietz

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
cfr...@my-deja.com wrote:

> In practice we have plenty of H2O emitters already, as well as emitting
> CO2, most power stations, factories, motor vehicles and aircraft emit
> vast quantities of H2O into the atmosphere, and there seems to be
> little measurable increase in cloud cover.

Not to mention the hundreds of cubic kilometers of liquid water
that get evaporated through agriculture every year.

Any water vapor emission from hydrogen combustion is going
to be globally unnoticable, and cannot have long term
cumulative effects. The water cannot build up in the
atmosphere.

Paul

Paul F. Dietz

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
cfr...@my-deja.com wrote:

> Actually we do, billions of tons of water vapor are released to the
> atmosphere right now by the very same sources which are emitting CO2.
> The impact on the climate/environment of these massive H2O emissions
> is negligible, compared to the CO2 emissions.

And, compared to the the hundreds of thousands of cubic kilometers
of liquid water that evaporate naturally each year, mostly from the
oceans.

Paul

Ian Montgomerie

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
On Fri, 21 Apr 2000 09:21:06 -0400, cam...@SPAHMTRAP.heliograph.com
(Cambias) wrote:

>> This is simply another method of storage, within the intent of my
>> remark.
>>
>> The cost of your hydrogren based electoysis system will be high, and
>> will dominate the overall system cost, higher than the cost of the
>> solar collectors.
>>

>And it should be noted that water vapor -- which is what fuel cells emit
>-- is an even better greenhouse gas than carbon dioxide.

The problem with CO2 is that it builds up in the atmosphere. Added water
vapor seems to be removed by the well-established natural cycles for
removing water vapor from the atmosphere. Like rain.


Ian Montgomerie

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
On Fri, 21 Apr 2000 10:59:51 -0400, cam...@SPAHMTRAP.heliograph.com
(Cambias) wrote:

>In article <3900600A...@interaccess.com>, "Paul F. Dietz"
><di...@interaccess.com> wrote:
>
>> Cambias wrote:
>>

>> > And it should be noted that water vapor -- which is what fuel cells emit
>> > -- is an even better greenhouse gas than carbon dioxide.
>>

>> And it should be noted that this is a rather blatantly
>> idiotic canard. CO2 emissions tend to increase
>> atmospheric CO2 levels for decades or centuries, while
>> water vapor emissions have no long-lasting effects as
>> the water precipitates out.
>>
>"Canard?" I'm insulting water?
>
>It's not blatantly idiotic because we don't know if really extensive water
>vapor emissions will precipitate out so easily.

Ahem. Turning every power source in the world into fuel cells would, AFAIK,
result in a water vapor release that is quite trivial compared to the
natural evaporation from the world's bodies of water. Which do, after all,
cover most of the Earth.

We're capable of CO2 emissions that are "really extensive" in comparison to
what is already emitted, but not water vapor emissions.


Archie Robertson

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
On Fri, 21 Apr 2000 13:11:19 -0700, "pervect" <perv...@netscape.net>
wrote:


>


>It seems pretty obvious to me that if we are really serious about reducing
>greenhouse gasses, with our current technology we will have to start relying
>more on nuclear fission plants. This isn't something I'm really wild
>about - the nuclear industry is just as bad as everyone else, they've got
>people claiming that ionizing radiation is "natural" and "good for you"
>(radiation hormonesis).
>


I would say that hydroelectric is a much better solution than nuclear
fission. It has very little impact on the enviroment, and is also
quite safe.

what we really need is neclear fusion...

Charles F. Radley - CSQE -Oregon L5

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to

>What does it cost to place a square kilometre of photocells with
>supports and cabling in geostationary orbit?
>

I thought you'd never ask :-)

Here is a nice sumary from Tom Abbott:-


Subject: Cost-Competitive Solar Power Satellites (was Re: The solar
power
satellite)
From: tab...@intellex.com (Tom Abbott)
Date: Sat, 08 Nov 1997 22:14:06 GMT
[begin quote]
If we wanted to supply 2,400 megawatts using thin-film solar power
satellites, what would it cost? Let's use the 10 GHz bicycle wheel
SPS with a mass of 50 tons and an output of 110 MW, which means we
need to put 22 thin-film SPS in geosynchronous orbit (GEO) to equal
the output of the three nuclear powerplants.

We don't have a launch vehicle capable of putting 50 tons in GEO in
one launch so we need to develop one. Estimates for a shuttle-derived
heavy-lift vehicle (Shuttle-C) of this capacity are around $3 billion
in development costs, and George H estimates his Big Dumb Booster
(BDB) at about the same development cost.

George thinks he can launch his BDB for about $50 million per launch
and I think a Shuttle-C can be launched for about the same, so I'll
use $50 million as the launch cost for each SPS.

Heavy-lift vehicle development= $3 billion

Cost to launch 22 SPS= $1.1 billion

Now, if the SPS materials costs, ground facilities and receiving
antenna costs are around $5 billion, then thin-film SPS look superior
to nuclear powerplants, especially when you consider that the costs of
nuclear cleanup have not been calculated into the cost comparison,
and, for the future, the next 22 SPS put in orbit will not incur the
$3 billion development cost for the heavy-lift launch vehicle since
it's already developed.
===================================

>> Hydrogen is very difficult to contain, it is almost like Helium, it escapes
>and
>> diffuses through containers which are nominally hermetically sealed.
>
>I would have guessed that it was worse than helium. Diffusion rates
>depend inversely on molecular mass if I recall correctly.
>

It is the size of the molecule, He being monatomic has a smaller molecule than
H2 (diatomic).


>Australia's GHG emissions was that our modern loss-distance gas
>pipelines are adequate to carrying hydrogen, provided that the
>compressors and regulators were replaced with more suitable designs, and
>provided that a little CO2 was included in the hydrogen (something about
>adsorbed hydrogen making components brittle.
>

That sounds realistic.

But in the third world, there is nothing to convert. They are currently
building natural gas pipelines at a fair rate.

>> The main question of course is whether such a system could econmically
>compete
>> with space solar power.
>>
>> The answer is by no means obvious.
>
>Quite true.
>
>Perhaps the issue is one of timeframe. I am thinking to a system that
>could be delivering power on an commercial scale within ten to fifteen
>years. When we have colonies in space and on the Moon the cost of
>orbital power stations might not be so high.
>

You jumped ahead of me , hah.

The timeframe depends on the level of interest and the flow of investment
capital.

Some nice demonstrators could be launched in the 5 year timeframe.

But even terrestrial solutions will take years or decades to put in place.

Paul F. Dietz

unread,
Apr 22, 2000, 3:00:00 AM4/22/00
to
Archie Robertson wrote:

> I would say that hydroelectric is a much better solution than nuclear
> fission. It has very little impact on the enviroment, and is also
> quite safe.

It has a large impact on the environment, is very unsafe,
and is inadequate to replace fossil fuels.

Other than that, it's ok. :)

Paul

Brett Evill

unread,
Apr 23, 2000, 3:00:00 AM4/23/00
to

> > >
> > But I agree with you about fission. It has dangers and it causes


> > pollution, and therefore it kills people. But estimates indicate that
> > the nuclear fuel cycle kills an order of magnitude fewer people per
> unit
> > energy supplied than the coal power cycle. I haven't seen figures for
> > oil, but I'm far from happy about the number of oil spills at sea we
> > currently tolerate.
> >
>
> By comparison, what do you think of the safety or health risks of
> microwave power beams ( at 1 KW/square meter) ?

I don't know enough to have an opinion. 1 kilowatt per square metre
doesn't sound like much: it is less that the areic power of sunlight. I
am assured that the wavelengths that would be used would be ones that
are not absorbed by biological materials. And I think that microwaves
are not ionising.

A very substantial portion of the danger to health and life involved in
fossil fuel cycles is in the extraction and transport of bulky fuels. I
don't guess that microwave power beams would involve risks of that sort.
And dangers involved with the launch could be 'amortised' over a fairly
long useful life. It sounds like a fairly safe technology, just rather
expensive.

Regards,


Brett Evill

Brett Evill

unread,
Apr 23, 2000, 3:00:00 AM4/23/00
to
Archie Robertson wrote:
>
>
> I would say that hydroelectric is a much better solution than nuclear
> fission. It has very little impact on the enviroment, and is also
> quite safe.

I can't agree. A hydroelectric dam doesn't have a widespread effect on
the environment, but it does have an intense effect where it does
effect. Few forests are ever so thoroughly polluted as those which are
drowned under thirty metres of water. You may like lakes. But that
doesn't mean that turning all high valleys into lakes is not a good
idea. We had some controversy here in Australia in 1983, in which the
Federal government had to take action under its foreign affairs power to
prevent the Tasmanian state government from flooding the Gordon and
Franklin river valleys. These two valleys are the last remaining
examples of the biome they contain, and are (now) protected as a World
Heritage site.

I haven't seen the figures, but I guess that hydroelectric power
generation is comparatively safe. But don't forget that workers are
killed building dams, and that when dams do burst, destruction of
livelihoods and loss of life in the valleys below can be copious.

Regards,


Brett Evill

Phil Fraering

unread,
Apr 23, 2000, 3:00:00 AM4/23/00
to
Brett Evill <b.e...@nospam.tyndale.apana.org.au> writes:

> Archie Robertson wrote:
> >
> >
> > I would say that hydroelectric is a much better solution than nuclear
> > fission. It has very little impact on the enviroment, and is also
> > quite safe.
>
> I can't agree. A hydroelectric dam doesn't have a widespread effect on
> the environment,

Are you sure? I was under the impression that they interfered with the
flow of sediments from upstream in the river valley to the lower river
valley and eventually the ocean.


--
Phil Fraering "There's a vampire!"
p...@globalreach.net "...In the parcel!"
/Will work for tape/ "...In the kitchen!"
"...Hate Mail!"

Peter Kwangjun Suk

unread,
Apr 23, 2000, 3:00:00 AM4/23/00
to
On Fri, 21 Apr 2000 13:11:19 -0700, "pervect" <perv...@netscape.net>
wrote:

>It seems pretty obvious to me that if we are really serious about reducing
>greenhouse gasses, with our current technology we will have to start relying
>more on nuclear fission plants. This isn't something I'm really wild
>about - the nuclear industry is just as bad as everyone else, they've got
>people claiming that ionizing radiation is "natural" and "good for you"
>(radiation hormonesis).

There is also the proposal to capture and sequester the CO2. This was
featured in a recent Scientifc American. (Feb 2000)


--
Peter Kwangjun Suk
Cincom Systems, Inc.
s...@pobox.com http://ostudio.swiki.net
(comp.lang.java.advocacy killfile poster-child -- Scene, not Herd!)

Mark Atwood

unread,
Apr 23, 2000, 3:00:00 AM4/23/00
to
ps...@cincom.com (Peter Kwangjun Suk) writes:
>
> There is also the proposal to capture and sequester the CO2. This was
> featured in a recent Scientifc American. (Feb 2000)

When and if the Greens in the wealthy nations do force thru a "carbon
tax", the money should not be used for "ordinary government
spending". Instead it should pay for a identical tax credit for carbon
sequesting.

For example, if the tax was $1 to emit 100 kg of carbon, there should
be a tax credit of $1 to sequester that much carbon.

I can see an entire industry springing up to sequester carbon. We
could base aid to the developing world on it, even.


--
Mark Atwood | It is the hardest thing for intellectuals to understand, that
m...@pobox.com | just because they haven't thought of something, somebody else
| might. <http://www.friesian.com/rifkin.htm>
http://www.pobox.com/~mra

Brett Evill

unread,
Apr 24, 2000, 3:00:00 AM4/24/00