Re: food from space

On Apr 24, 6:36 am, Ian Parker <ianpark...@xxxxxxxxx> wrote:
On 24 Apr, 00:59, Willie.Moo...@xxxxxxxxx wrote:



NASA did studies on space colonies back in the 1970s and 80s.  Gerard
O'Neill wrote on them in The High Frontier.

http://space.mike-combs.com/SCTHF.html

The costs do not take into account the ability of developing the
technology more gradually in a way that sees it more of an investment
that earns profits, which are then re-invested in technology
development.

One interesting finding was that farms in space support 40,500 people
per square kilometer at US per capita levels of consumption.  This
amounts to 730 kg per person per year.   To fee 6.6 billion people at
this level requires 162,963 square kilometers of pressure vessel
area.

103,745 spheres each 1 km in diameter each housing a spinning cylinder
707 meters in diameter and 707 meters deep, support 1.57 square
kilometers of growing area - each supporting 63,585 persons.

Each satellite has a rail gun and fires 2 meals per second - to people
all over the Earth aided by low cost GPS guidance systems and ceramic
aerogel thermal protection systems with aerodynamic features.  MEMs
based rockets forming a propulsive skin to execute a soft landing at
the desired location for each meal.  Terminal velocity of the aerogel
encased meal is about 200 m/sec following re-entry - which requires a
propellant fraction of 4.3% or 30.4 grams of propellant for a 700 gram
meal.  The rail gun fires it to the targeting envelope and the kinetic
energy and tail fins of the falling meal are adjusted to bring it to a
precise GPS cooerdinate. A solid state doppler radar determines
precise altitude to ignite the engines, and bring the meal to a halt
at zero altitude at the desired location.

90% of the world's population live in 10% if the world's land surface.

But they farm nearly all the arable land to feed themselves. Cities
are not places people grow food.

I thin that perhaps a more cost effective solution would be to grow
food on part of the 90% of land surface.

Your numbers are approximately correct. However, please understand
that all the arable land that can be farmed IS being farmed.
Increasing the productivity of those lands would involve radical
engineering that is more costly per acre than the cost per acre I'm
proposing above - that's why costs are so important. Certainly simple
low cost solutions should be used early on. What are those?
Ultimately however, the ability to produce very low cost pressure
vessels, at less cost than converting arable land to production, will
tend to favor that use. Its all a function of cost. The point is,
space development is relatively unlimited, whilst terrestrial
development is very limited and very mature.

Deserts which consitute 30%
of the world's land is a good candidate.

Nothing grows in deserts. To make use of deserts requires a massive
engineering effort - more massive than building the pressure vessels
from asteroidal feedstock. Furthermore, the political and economic
and social conditions in which this engineering project is undertaken
on Earth is far less controllable, and hence costs and time frames are
far less controllable when compared to the benign political conditions
in space.

A far better solution therefore would be to export microwaves -

The rayleigh criterion in optics tend to favor concentrated
photovoltaics driving free electron lasers having a greater efficiency
than klystron tubes - to beam band gap matched energy to terrestrial
solar panel array at 1,100 nm wavelength.

not
food

Why? You are not arguing from any detailed analysis of cost. I said
at the outset, as production in space grows, at some point pressure
vessels will be built at less cost than green houses on Earth. At
that point, given the very high productivity of space based
agriculture, we'll be able to produce and deliver foods from space far
more cheaply and with far less hassles than we can on Earth.

For example, consider what happens when you order a pizza. You dial
the phone place your order, give your credit card information and the
pizza arrives. Some driver had to haul the pizza in a car from the
kitchen where it was assembled and baked and packaged - encountering
rolling friction and stop and go traffic all the way. Before that the
flour, tomato sauce, cheeses, sausages, and spices all arrived from a
variety of food wholesalers, by truck. Those wholesalers received
those products from food packagers by truck, rail, ocean, or plane.
Packagers received their products from farms or specialty jobbers.
This too arrived by truck, train or boat. The energy to transport
and cook your pizza exceeds the energy to grow and harvest the
products that went into your pizza.

Say your pizza uses a bit of real italian parmesano cheese mixed into
the 4 cheeses the pizza is laced with. That cheese is made from milk
in Italy. It is aged, and graded and sold, and resold and packaged
and shipped from Italy. It then arrives in the USA say, and goes to a
warehouse, where it is shipped to a food wholesaler, who ships it to
your pizza place where it is ground and assembled with the other
ingredients on your pizza backed and packaged for delivery and
delivered.

Now imagine the land that all that food grows on, and all those pigs
and other meat animals live on, transported to a pressure vessel on
orbit. This pressure vessel is made at less cost per area than the
cheapest land around on Earth. Imagine that all the farmers and
helpers and whatnot, in all the stages of production, are brought to
orbit telerobotically using equipment that costs less than 1/2 the
price of an automobile - that all of them now use to drive to work.
Now imagine that in response to your telephone call a GPS coordinate
is provided and your pizza is made from fresher ingredients, with less
handling, and shot directly from orbit to your front door.

Guess which takes less energy? The orbital system
Guess which takes less handling? The orbital system
Guess which takes less capital costs? The orbital system

The famrland on orbit is less expensive than the farmland on Earth
The capital equipment to tarnsport, store and handle supplies is less
The cost of getting labor to work is less
The cost of energy is less
The productivity of labor is higher
the productivity of capital is higher
the productivity per acre is 10x higher
The political hold ups and costs are lower
The constraints on growth are less

and use the energy to desalinate sea water.

The critical component in anything is the cost of capital to generate
that energy and the cost of capital to use it. i have sponsored
several projects in the world, one in Dubai, several others in
Australia, to use solar energy to desalinate seawater and use the
fresh water for agriculture, and sell the salt.

The cost ofmicrowave based systems thus far are not competitive. The
cost of my solar panel systems are competitive

http://www.usoal.com


This would have to
compete of course with terrestrial solar power. We have I think
already discussed the pros and cons.

Its all a matter of cost. For agriculture you need distilled water.
DI water won't work - since enough salt remains to build up in the
soil. It takes 2,300 kJ to boil a liter of water. It takes several
kiloliters of water to produce a metric ton of foodstuffs. So, each
person you support in this way will need about 18 GJ - equivalent to 3
barrels of oil in energy - of energy. To feed 6 billion people like
this will require the equivalent of 18 billion barrels of oil per
year. The Earth uses about 28 billion barrels per year today - not to
boil water but for everything else - so you can see just to keep you
supplied with fresh water requires a substantial infrastructure.
Processing water in the vacuum of space using solar systems directly,
require far less infrastructure at far less cost.
.
As a European my focus tends to
be the Mediteranean, the Middle East and N Africa rather then the
South West although any remarks I have made is equally applicable.
Deserts if watered are amazingly fertile.

A ring of stations in sun synchronous polar orbit flying above the
terminator of Earth- will place them in constant sunlight. All
satellites will fly above all points of the Earth twice a day.
Products will be delivered to anyone anywhere at sunrise and sunset -
within 10 minutes of placing an order without any border hassles.

There is one snag with the scheme which you propose and that is that
is that you need to transport water and CO2 to your space stations. If
you had pure recycling this problem would not arise.

There is no recycling of products, although there is no waste. All
the material leaving as foodstuffs, must be replaced by importing it
from the asteroid belt. The same infrastructure that allows the
construction of the ring, allows its continued maintenance. It only
requires a 5 km/sec delta vee to import items from the Asteroid belt.
That's 12.5 MJ per kg, or 12.5 GJ per ton. - which is less than the
energy needed just to boil water in your desert scheme.

My proposal therefore is a canal/pipeline to take water from the
Mediteranean across Lebanon to Damascus.

Building a canal of this magnitude (wide enough to have the water flow
needed,and deep enough to allow gravity to let it flow where you want
it) nvolves moving Earth that masses 100x the mass of the orbital
system described.

If we were to have peace, and
a joint project would help cement peace, canals could go through
Israel.

A salt water ditch wide enough to have adequate water flow, and deep
enough to have it flow downhill FROM the ocean, involves MASSIVE
trench being cut in the land, which involves moving lots of material
in a high gravity field.

No agreements between enemies are needed to capture asteroidal
fragments and process theminto useful products on orbit.

While we have vast eperience building canals and no experience other
than CERN and FermiLab building large pressure vessels, we shouldn't
let our prejudices blind us to the results of actual engineering
requirements when making decisions about our future.

Solar power, initially terrestrial, would be used to
desalinate Med water thereby opening up vast areas for agriculture.

Yes, I produce solar panels at $0.07 per peak watt, and have a $0.02
per balance of system cost. I have adapted these systems for
desalination. Adding bandgap matched laser satellites on orbit
increases energy output 16x at an added cost of $0.30 per initial
installed watt using my CPV/FEL approach.

The dry fountains in Damascus have left an impression on me,
particularly when the energy from 2 or 3 roofs would be enough to
supply them with water.

Depends on the evaporation rate.

http://www.portlandonline.com/water/index.cfm?c=ecdei

A typical fountain uses 5,000 gallons per minute. That's 18,181
liters per minute. assuming in the desert climate you have 10%
evaporation rate in the desert - of the water spray - that's 1,800
liters per minute evaporating from 18,181 liters per minute. Divide
by 60 to obtain 30 liters per second. A required 2,300 kJ/kg - which
is 2,300 kJ/liter - that means you need a boiler with 69 MW of
capacity to provide the desalination energy per fountain - to get it
from seawater as you propose. A typical rooftop in that region of the
world is 100 sq m. Three rooftops would be 300 sq meters. At 18%
efficiency, this produces .54,000 watts when the sun shines. The sun
shines in this region about 9.6 hours per day. With cosine losses
this is an average output from those three roofs 15,270 watts
continuous. You are off by a factor fo 4,518 per fountain.


I feel all told this is a far better bet.

You may feel that way, but you have not demonstrated that your feeling
is based on any real world analysis of what you have proposed or any
real world understanding of what I propose.

  - Ian Parker- Hide quoted text -

- Show quoted text -

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