Recycling and efficient production on Earth vs. mining the sky

> Let me add my own. Is it better to have the mining and pollution here
> on Earth or in orbit?
>
> http://www.faultline.org/place/2002/04/toxictech.html
>
> "In 1993, Texas Instruments estimated the resources required and
> waste produced in the manufacture of a single six-inch semiconductor
> wafer. (In the intervening nine years, production has likely become
> more efficient, but more recent industry-wide estimates are
> unavailable.) Producing one wafer required 3200 cubic feet of bulk
> gases, 22 cubic feet of hazardous gases, and 20 pounds of chemicals,
> along with 285 kilowatt-hours of electrical power (enough to power a
> refrigerator around the clock for several months) and 2,275 gallons
> of water (enough for over 70 bathtubs). Each wafer's production
> generated seven pounds of hazardous waste, 25 pounds of sodium
> hydroxide, and 2840 gallons of waste water."

[Just mostly rehashing old stuff, but what they hey.]

Two points related to your quote, then another related to your statement:

Your figures here are out of date (if they were even accurate at the
time -- especially given the water could be filtered and reused).

See for example:
http://www.eere.energy.gov/solar/man_pro_implications.html
"Because manufacturers use a wide variety of processes to make PV cells,
a wide range of chemicalssome of them toxic or hazardousare employed
in PV cell production. In terms of worker safety and health, simple
protective and administrative measures can be used effectively to
protect those who produce PV systems. In terms of the environment, the
PV production process produces small amounts of waste materials, but
this is minimal relative to the emissions from conventional energy
sources. Most of today's PV cells consist of crystalline or
multicrystalline silicon. Silica particles can be released in the mining
and refining stage, but these present a hazard only to workersone that
can easily be avoided. Silicon PV module production can include
fluorine, chlorine, nitrates, isopropanol, sulfur dioxide, carbon
dioxide, silica particles, and solvents. According to a report from
Utrecht University, "Estimated air emission is maximally 0.16 [kilograms
of fluorine] and 430 [kilograms of chlorine] per [1000 megawatt-hours]
of electricity supplied by PV modules, which is orders of magnitude
smaller than the corresponding emissions of a coal plant." According to
the same report, neutralizing etching and texturing solutions and flue
gases can yield water-borne fluorides and chlorides. But these are still
three to five times smaller per unit of electricity than those produced
by a coal-fired plant. Alternative etching, texturing, and purification
methods can reduce those emissions. Using sulfur-containing carbon
sources in the reduction of silica also produces negligible amounts of
sulfur dioxide and carbon dioxide. Solvents and alcohols used in the
process could contribute to ozone and smog if they are emitted into the
atmosphere. But EPA regulations limit the amount of such chemicals that
can be released into the air, and simple emission controls can filter
out those pollutants in a plant's exhaust system. A detailed examination
of these issues is presented in a July 1998 technical paper produced at
the National Renewable Energy Laboratory, "Environmentally Benign
Silicon Solar Cell Manufacturing."
http://www.nrel.gov/ncpv/pdfs/tsuo.pdf

According to page 5 of that PDF, "The chemical waste generation has been
reduced by nearly 75% since 1990 ...".

And I would expect even more reductions if this is made a priority.

Now let's try to compare figures as best we can. Note that a typical 150
watt panel operating in, say, 3 hours a day of peak sun 365 days a year
for thirty years lifespan generates 4927500 watt hours of power, or
about 0.005 of a 1000 megawatt-hours. So the amount of fluorine emitted
for that panel must be about 0.005 times 160g equals 0.8 gram of
fluorine by what is on that web page. Do the same for chlorine and it is
2140 grams of chlorine emitted. So, that may be a release of couple
pounds of hazardous waste, but in this case the solar panel might be two
meters tall by one meter wide, so about 36 of those wafers. So amounts
per wafer would be about 60 grams of chlorine. Anyway I don't have the
numbers to compare for the other things mentioned, but you can see at
least here are the beginnings a big difference in waste figures assuming
these were the two dominant gasses as waste products involved.

But for the other point, let's say your facts were correct and current
anyway. What is the implication? If we beam down a lot of power from
space, a lot of IC chips will be made, right? And a lot of other things
that produce toxic waste (snowmobiles, cars, houses, conventional
agriculture products like pears, etc.). So, pollution will happen anyway
unless the manufacturing technology is changed. So we all will be buried
in toxic waste eventually, even with free clean space power. One might
argue it might be somewhat slower with clean space power (and we need to
know what fraction of the waste stream comes from power production as
opposed to consumer goods to know how much of a difference) but in the
end, buried is buried, even if it is (guessing) 10% years later.

Oh, you'll say, with lots of free space power, we can take all toxic
waste and ionize it and separate it and reuse it and make everything
clean. Well, OK, let's say we can do that. But then, why can't we do
that with power generated by PV? And thus, we can clean up all the waste
generated by PV production. I picked ionization as the most general, but
similar reasoning would apply for any scenario for recycling or
producing products in general with less waste -- they could probably
apply equally to PV production.

You can't have it both ways. Either we will bury ourselves in waste even
if the power source is clean (but perhaps slightly later), or we will
develop ways to minimize the production of waste through efficient
manufacturing and recycling, in which case space based PV has no lasting
environmental benefit over ground based PV.

Now, getting back to your original statement, similar to that which
Gerry O'Neill raised in his undergraduate physics classes and in _the
High Frontier_, "Is it better to have the mining and pollution here on
Earth or in orbit?". Let's use his more general question: "Is the
surface of a planet the right place for an expanding industrial
civilization?" And I'd agree the answer is no. There isn't much room to
expand compared to space. Also, the notion of cities in space with
indefinite surface area might ease tensions on Earth -- making it seem
silly to fight over land on Earth for most people. There aren't as much
accessible raw materials on Earth; asteroids have enough material to
make millions of times the Earth's surface area in space habitats, and
that's not even getting started on disassembling moons and planets. The
Earth's ecology is unique and many species are being lost through
habitat destruction for new building or mining projects, so if most
people could leave the planet for space settlements, then the ecology
could remain more diverse; this would also reduce thermal pollution
which effects some species. Solar power is almost continuously
accessible in space without a need to store it (as you like to point
out. :-) A space based civilization would be more resistant to a single
disaster like a big comet hitting the Earth. And so on. So those are all
good arguments for saying "most people could be happier living in cities
in space", but they are not necessarily good arguments for saying "let's
bring products or energy from space to the Earth" IMHO. Again, if the
Earth is not to be buried in waste, it needs to have ways to locally
recycle materials. Once you have those, you have no real need for space
resources as opposed to just using those resources in space to make
space settlements (essentially just more real estate).

After all, on Earth, the metal in a car doesn't disappear after you junk
it. You can reuse it almost endlessly (subject to small losses to the
atmosphere with each cycle perhaps). So mining the sky
http://www.asi.org/adb/b/01/miningthesky.html
doesn't make much sense unless you are also building in the sky IMHO
(given the need for recycling on Earth anyway).

Again, I'm all for space settlement. I think we should be bold enough to
justify it as an end in itself -- not because power or raw materials or
even finished goods will be brought back to Earth. IMHO if anything of
value will come back to Earth from space settlements, it will probably
be information -- new ideas, new cultures, new perspectives, new ways of
being, new inventions, even new species. And I think that reason enough
to make space settlements happen (though I also think the same ideas can
be used to make sustainable settlements on Earth, so I see almost no
conflict between working on space settlements and working on sustainable
Earth settlements). See for example:
http://www.bfi.org/designsc.htm
"Design Science is a problem solving approach which entails a rigorous,
systematic study of the deliberate ordering of the components in our
Universe. Fuller believed that this study needs to be comprehensive in
order to gain a global perspective when pursuing solutions to problems
humanity is facing."

I also think it is silly that people now recognize the importance of
global threats like nuclear war or engineered plagues or billions of
people starving from monoculture failures or so on as important to worry
about (all of which were once sci-fi, but are realer and realer
possibilities), but then think it is sci-fi or blue sky to talk about
space settlements or self-replicating automation or reorganizing
manufacturing knowledge and techniques as part of the response to those
threats. We have, for good or ill, become an industrial civilization,
and there is no way back to the (essentially work free) lifestyle of
hunting and gathering without a major population reduction on Earth,
http://www.eco-action.org/dt/affluent.html
so the only way forward is IMHO a Bucky Fuller type design science
revolution (coupled with social justice issues too)
http://www.deoxy.org/endwork.htm
which naturally includes decentralized ecosystems in (networked) space
settlements. I think space settlement as a cause will get further
promoted as part of an optimistic package of the future (as in the
optimism of _2081_), than trying to fight it out now with ground based
alternatives over how to generate more centralized power.

--Paul Fernhout