# [ExI] cure for global warming

Keith Henson hkeithhenson at gmail.com
Tue Dec 28 15:43:08 UTC 2010

```Guys, I am not trying to shoot down the idea, in fact I heard an hour
presentation on it a couple of years ago.  But let's consider the
physics of the proposal.

On Tue, Dec 28, 2010 at 5:00 AM,  John Clark <jonkc at bellsouth.net> wrote:

> On Dec 27, 2010, at 2:43 PM, Keith Henson wrote:
>
>> I can tell you it isn't that easy to keep a pipe up to 12.5 miles, much less 18.
>
> Well, moored balloons have actually been built that have reached an altitude of 5 miles, and they were carrying heavy broadcasting or radar equipment not the garden hose I'm talking about, and they were dirt cheap. I'll tell you one thing, 18 miles sure would not cost several trillion dollars a year as some say we must pay to solve global warming.

"Myhrvold wasn't suggesting anything as ambitious as a space elevator,
just a light hose  about 2 inches in diameter going up about 18 miles.
In one design he burns sulfur to make sulphur dioxide, he then
liquefies it and injects it into the stratosphere with a hose
supported every 500 to 1000 feet with helium balloons. Myhrvold thinks
this design would cost about 150 million dollars to build and about
100 million a year to operate. In another design that would probably
be even cheaper he just slips a sleeve over the smokestack of any
existing small to midsize coal power plant in the higher latitudes and
uses the hot exhaust to fill hot air balloons to support the hose."

18 miles is close enough to 29 km.

There is a good reason to send the SO2 up as a liquid, for the same
velocity it would take a much larger pipe which generates more wind
drag and takes more excess buoyancy to keep it close to vertical.  So
how much pressure does it take at the bottom to pump it up 18 miles?
The sg is 1.46, so a cubic meter would mass 1460 kg.  In one g, this
takes a force of 14308 N to hold it up.

One bar is 100,000 N/m^2 which is close enough to 7 meters per bar.
29,000 m / 7m/bar is 1443 bar or 60,000 psi.

Some garden hose.  :-)

How much will the hose weigh?  How much wind resistance?

How much excess buoyancy?  How much lift gas?

It isn't simple.

Eugen Leitl <eugen at leitl.org>

>
> On Mon, Dec 27, 2010 at 12:43:44PM -0700, Keith Henson wrote:
>>
>> Over a year solar energy averages a few hundred watts per square
>
> The solar constant is 1.366 kW/m^2. Many people, especially
> at higher latitudes, find that by itself a considerable
> challenge to handle. The amount of land area covered by
> buildings is well in excess of the total energy budget.
>
> We don't have the area problem. We have the scaling up of
> intercept (antenna) area problem. (And smart grid redistribution,
> sure).
>
>> meter.  Then you take the efficiency loss in the PV cells of at least
>> 75%.
>
> Efficiency is irrelevant as existing conversion efficiencies
> are more than adequate, ROI and EROEI are the only relevant factors.

1/efficiency is a direct cost multiplier for ROI.  Combined cycle
plants are more expensive than gas turbine alone, but they are worth
it because of the higher efficiency.

>> The inside of a power boiler is in the tens of MW, and the efficiency
>
> The inside of the power boiler requires steady influx of
> external fuel, so you better integrate over the entire
> fuel cycle. And of course coolant is already scarce during
> the summer months, so the power boilers have to be shut
> down, natch.
>
> And of course there's not much more fuel where that
> came from, so the question is academic. So learn how
> to stop worrying, and learn how to love your renewables.
>
> I have a deja vu of the 1970s. What is up with transhumanists
> being mired in decades old thinking that has proven not
> to work?

I have been working on solar for years.

As a rule of thumb, an "no fuel" energy investment makes sense when
you can get return of capital invested in ten years.  For power you
can produce 80,000 kWh in that time.  So you can spend about \$800 per
penny a kWh you are charging.  So for penny a kWh, you can't spend
more than \$800 per kW, or \$800 M per GW.  You can see that \$8 B for a
nuclear plant isn't going to make power cheap enough to convert it to
liquid fuels at reasonable prices.

>> is around 45%.  (60% for combined cycle.)
>
> Efficiency is still irrelevant. Today's solar PV
> efficiency ranges from few % to almost 50%, but it's
> the ROI and the EROEI that dominates.
>
>> > Solar flux upon outer residential
>> > building skin is enough to power it. In fact, Si PV rather likes
>> > it cooler, so you need backventilation to make it approach optimum.
>>
>> Powering houses is nowhere close to the whole energy problem.
>
> So double the budget, and you're in the green for industry
> as well.

It's more like 5 times.  There is a remarkable amount of energy in oil.

>> > Many human activities are following diurnal cycles, and cheap nocturnal
>> > power is an artefact of large plant thermal inertia and dynamic market
>> > pricing. You can assume nocturnal demand will collapse if price
>> > was to double or triple.
>>
>> I thought the object was abundant low cost energy.
>
> Before you can walk you must first learn to fly. In order to
> do SPS you must first cover at least 10% of total electricity
> budget from terrestrial thin-film PV.

Why?  It is not at all obvious that PV is the right answer for power
satellites.  With low temperature radiators stacked Rankine cycles or
Brayton/Rankine will have 1/4 the area of a 15% PV system.

snip
>>
>> It's just chemistry, and well understood chemistry at that.
>
> Infrastructure is most assuredly not chemistry, these days "just chemistry"
> is anything but that, and RT renewable synfuels have several
> Nobels up their sleeves.
>
> Many things are cheap these days, but infrastructure and chemical
> R&D definitely not.

As I pointed out, there is already in existence billion dollar plants
that make synthetic fuels.  All you need to run them on air and water
inputs is oceans of energy (to make hydrogen and sort out CO2).

snip

Keith

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