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re: concentrator questions & clarifications
28 apr 1997
alan wrote:
>nick pine wrote:
>>>...electricity from steam requires moving parts and just plain more parts,
>>>making it inherently higher-maintenence and less reliable than something
>>>like pv...
>>agreed, but we all take risks, eg in automobiles, where our chances of dying
>>are about 1 in 5,000 per year... seems like a multidimensional choice...
>sure, it is a multidimensional choice, but lets look at this purely from
>a marketing point of view. i do not think small steam systems would be
>popular.
but neither pv nor solar steam electricity make economic sense, given a grid
connection. otoh, it could be a fine hobby, doable on a tiny scale, giving one
a token sense of being part of the solution. it's nice to be able to plug a
single pv panel into a wall socket, these days. more interesting maybe, for
most people, than replacing an incandescent bulb with a cf, or tacking a
plastic greenhouse onto the side of a house to heat it.
>no matter how much power the thing puts out, no matter how big the savings,
>i just do not think you will find anyone willing to plant one of these
>contraptions in his/her backyard.
it's better to plant it in a sunspace, where the warm surroundings lower its
thermal loss, which in turn heats the sunspace air, which in turn heats an
attached house in the winter. rational people would not do this: it takes
heroic people like the pennsylvania live steam association (around the corner
from my house) who spend all their weekends riding around their 20 acres of
tracks over tiny trestles, etc, with railroad hats in railroad uniforms atop
their small smoky trains, 10-20' long. they are just having fun (puff puff,
hoot hoot), not trying to save the world... the sca might like this too, but
steam is a bit late for them (as are cavaliers, and forks.)
>>rudy often mentions that steam systems need attendents. i think part of this
>>comes from the history of steam boiler explosions.
>partially, perhaps, but remember that you still need to rotate a winding
>to generate electricity.
sorta like a washing machine, with fewer moving parts, and backwards.
>to keep this running at peak efficiency on any scale...
didn't we already decide it's not worth doubling the cost of the generator to
raise its efficiency from 88 to 92%? think bogart, and "the african queen."
>the shaft spinning your rotor must be kept properly lubed,
my brother tells me this is normally done with things called "bearings."
(he's a mechanical engineer who works for an unpronouncable swedish
bearing company.)
>as must the moving parts of your steam engine.
more bearings, and "lubricated steam" (pocketa pocketa pocketa...)
pvs do not make interesting noises.
>seals and other parts must also be properly maintained, not just for
>efficiency's sake but for safety's sake -- broken seals can fool even
>the most sophisticated safety systems.
an army of specially-trained, insightful, prussian boy scouts might help here.
("achtung! the seal is about to break! we must the sealmeister summon!")
>this is much more work than any type of pv installation requires.
but less than keeping a car running. more work than maintaining an oil burner
in the basement? how will people heat their houses in 40 years' time? (do you
wear parachutes when visiting skyscrapers, to afford a small extra margin of
personal safety, should the building decide to collapse when you are inside?)
>also, given the problems that solar-generated steam had in its first go-round
>i would be surprised to find many utilities taking serious interest in it...
hey, they could call it "green power" and charge more :-) use the same steam
turbines at lower power and sling the dishes inside the tops of their cooling
towers, focusing them by moving the thermal receiver suspended by 3 cables,
as in the very large radiotelescope at ariceibo? still cheaper than pvs...
>not that i'm conceding steam is better than pv -- just that you can
>achieve better absolute efficiency (for now)... :-)
and perhaps a heck of a lot cheaper and easier to repair, and more fun.
nick
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