Hi Tim:
Thanx for your reply. I hadn't thought about the alternative in terms
of Rosennean complexity... that's certainly not its genesis. But maybe
there are RR-complexity-theoretic aspects that just haven't occurred to
me. There's no question that it will emerge naturally when
RR-complexity is applied to the evolution of self-organizing (or more
precisely, self-stabilizing)
societal structures... so it's connected in at least that sense.
Hmmm... lemmee think about this for a while.
In the meantime, I'm reticent to bring it up here without some other
obvious tie to RR's work. Besides... I'm waiting to see what Judith has
to say about our mutual errors & misconceptions. Maybe I'm wrong
about everything.
;-)
Pete
Tim Gwinn wrote:
Pete,
Thanks
for the great summary of solar's potential. In a few
paragraphs you demonstrated, using simple "back of the envelope"
calculations, the basic theoretical limits of solar power. Why these
kinds of facts are not more widely disclosed has always baffled me.
As
for your alternative to combustion-based technologies, go ahead and
tell us! There must be ways in which complexity figures into it. :)
Regards,
Tim
(...Yeth, thatth the plural of "myth" with a lithp.)
Judith is correct in her preference for using renewable resources like
solar energy wherever they are appropriate. Tim is correct in his
assertion that intensive, reliable, on-demand power generation is not
one of those applications.
NOTE:
"Intensive" means that the
backup power generation technology is capable of completely replacing
centralized grid-supplied power (by which I mean your electrical
utility company) for any period of time that might be required to
provide an uninterrupted electrical energy supply. [ energy = power x time,
usually expressed in kilowatt-hours (kWh)]
"Reliable" means that the
backup power supply can operate as long as needed. If you want a
number, call it "a minimum of 95% operation/a maximum of 5% downtime
for maintenance".
"On-demand" means that the
backup power supply is available whenever you need it.
The economics of installing engine-driven generators must indeed be
balanced by the ROI such an investment would make. In addition to the
capital cost of the power generating, distribution, & switching
equipment, and the facilities to house it, there's the expense of
storing and recycling fuel (usually Diesel No. 2) -- with all its
associated regulatory hassles. Add to that the personnel cost of
maintenance & operations, and you have to have a very compelling
reason to load that kind of cost into the goods/services you offer your
customers. In fact, if your competitors decide against going that route
and the market prefers the resulting lower prices of their
goods/services, you won't have
any customers. Gas turbine technology has improved, but it's more
costly in capital & maintenance. Regardless, if you want reliable
backup and your market provides the economics to support it, you're
going to be going with some form of combustion engine-driven generating
plant.
Solar energy works pretty well in a thermal application -- that is, for
heating water and living space. Electrical power generation from solar
energy is an entirely different matter. It can
be used to generate electrical energy via photovoltaic conversion, as
long as one is willing to accept conversion losses on the order of 90%.
Even if such losses are acceptable, you still can only collect and
store enough energy to operate things like radios, stereos, and
high-efficiency lighting (e.g., fluorescent or metal halide vapor
lamps; forget about incandescent -- thermal losses are too high). But
if you want to do a lot of intensive usage (e.g., air conditioning,
electrical appliances, power tools), you're not going to be able to run
that kind of stuff using photovoltaic conversion without prohibitive
equipment & maintenance costs. The cost in lead-acid storage
batteries alone would eat you alive -- assuming you even wanted to have
that much hazardous stuff lying around.
I sympathize with the hopes of solar energy enthusiasts, but they would
perhaps be better served by a somewhat more realistic appraisal of the
ability of solar-powered infrastructure. As a source of large-scale,
intensive, reliable power generation, solar/photovoltaic conversion is
more mythology than technology.
Consider the physical constraints. The maximum terrestrial incident
power flux of solar radiation is ~1 kW per square meter when the sun is
directly overhead and is unobstructed. The sun's output imposes that
physical limitation, given the radius of Earth's orbit, and there isn't
much we can (or should) do about it.
Perhaps some concrete examples will help to illustrate how that
limitation affects our ability to use the sun as a practical source of
electrical energy. To convert the incident solar power to energy,
multiply by the amount of time that the 1 kWh/m^2 condition is in
effect. First, you must account for the seasons. The maximum solar
collection time that you can squeeze out is 12 hours per day, twice per
year... if your latitude is
somewhere between the two tropics. The rest of the year you have
considerably less daylight, and more atmospheric interference as the
sun's path drops to the horizon seasonally, so on average you have
maybe 10 hours of usable sunlight per day, under ideal conditions. If
your location is between one of the tropics and the nearest pole, it
goes downhill from there.
Now you must also account for the daily rotation of the Earth. Even
under the best of conditions (desert, during the summer, with no cloud
cover), you have that condition for maybe one hour before plus one hour
after the sun is at zenith. Of course, the sun isn't directly overhead
for the other 22 hours in the day, but let's say that you can devise
some complicated tracking mechanism to keep the perpendicular axis of
your solar collector(s) always pointed directly at the sun.
However, the average incident power won't be the full 1 kW/m^2 for the
entire 10 hours. Call it 0.70 -- again being generous. That gives you
~0.7 kW/m^2 x 10 hr/day = 0.7 kW-hours/m^2/day of incident solar
energy. Assume that you fill the entire 1-meter area with photovoltaic
cells and capture all the incident energy. With a conversion efficiency
of ~10% (that's typical of current technology), here's your maximum
electrical generating capacity, under ideal conditions:
0.7 kW/m^2 x 10 hr/day x 10% = 0.07 kW-hours/m^2/day
Now, since we've already accounted for the seasons in our average daily
capacity, we can annualize that capacity:
0.07 kW-hours/m^2/day x 365 days/year = 25.55 kWh/m^2/year
That's under ideal conditions...
meaning an arid climate with zero cloud cover. For the average location
in the U.S., cut that number in half... so that's ~13 kWh/m^2/year
Now, compare that capacity to the energy-intensive sources that we
typically find in fossil-powered electrical generating technology.
That's how Southern California Edison generates most of its power... by
burning fuel oil or coal, so for comparison, the same capacity can be
converted to the equivalent amount of fuel oil or coal:
Fuel Oil:
13 kWh/year x 3,414 BTU/kWh = 44,382 BTU/year
44,382 BTU/year ÷ 139,000 BTU/gal. = 0.32 gal/year
Anthracite Coal:
44,382 BTU/year ÷ 15,000 BTU/lb. = 2.96 lb./year
My average annual usage over the last 36-month period is 20,385 kWh.
Allowing for peak usage months, and based on my existing 0.25-acre lot
size, I could replace the energy I'm
currently getting from the grid if I were to cover 98% of my property
with photovoltaic cells... if
I had ideal conditions, and the
money to spend on such things, and the desire to live
amidst that sort of ugly junk, and the inclination to
spend my time or my money servicing/maintaining such a preposterous
facility. I don't. Most people don't.
More to the point, neither do the most vocally active "public figures"
who advocate the mythology of "soft energy" technology, and mislead
others to believe that such technologies are feasible.
I find the idea of energy self-sufficiency attractive as a means of
sustaining oneself when living in a remote location, but even then, I
would require a small generating plant if I wanted to maintain the
quality of life that I currently enjoy. The maximum conversion
efficiency attainable with current non-nuclear technology is
approximately 50%, provided by high-speed gas-fired turbines. I suppose
that when they can be made reliable enough and can be mass-produced
cheaply enough, it would be feasible for individuals to own them.
Nevertheless, such a decentralized system would sacrifice the economies
provided by large-scale, centralized power generation and distribution.
As long as we rely on combustion-based technologies, we might as well
minimize the combustion by-products via economies of scale. I should
think that would be an article of faith among anyone who is concerned
with global warming (I'm not).
Of course, the longer-term solution is to drop our reliance on
combustion-based technologies altogether. We have the capability to do
that safely right now, but (sigh) I'm not inclined to pursue such a
controversial subject in this forum... and besides, the content of this
post has probably wandered too far off-topic for this list as it is...
PVG
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