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re: concentrator questions & clarifications
1 may 1997
alan wrote:
>> but neither pv nor solar steam electricity make economic sense, given a grid
>> connection.
>sure they don't -- right now. but i thought this whole thread was about
>building something people would want (i.e., that would be cheap).
i'd like to help individual people build things they do want, today. "cheap"
seems part of that, but it's a matter of degree. seems to me no rational
person would try to compete with 2 cent/kwh utility power on a large scale,
but powering a suburban or city house with pvs or solar steam might be an
interesting "green hobby," and people who build beyond utility grids in the
us (even us route 50, "the loneliest highway" seems to have lots of wires
running all over the place) need a bit of electrical power. pvs also seem
too expensive for large scale third world electrification now.
>how much do you see the cost of solar steam electricity improving in the
>next 10, 20, 30, 40 years?
sorry, i can't find my crystal ball.
>pv currently costs $0.20-0.25/kwh (1994)
it seems to me that the cheapest pv panels cost at least $3/peak watt in 1997,
not counting inverters, installation, etc., and a peak watt might make
1 kwh/year. pvs last longer than 1 year, but that's a very large non-recurring
cost, compared to other ways of making electricity.
>and is expected to drop to $0.10-0.20 by 2000.
i guess you found your crystal ball.
>...regardless of whether you like these particular projections, it isn't a
>matter of whether pv will be economical -- it's a matter of when.
as it has been, for over 60 years :-)
>are the costs of mirrors and steam engines projected to decrease similarly?
it seems to me there's a larger potential for cost-reducing these systems,
since fewer people have tried, lately. mylar film costs about 15 cents/ft^2,
and turbochargers seem overpriced at $1000. dr. roland winston's two-stage
cassegrainian solar troughs with moving evacuated tube concentrators look
interesting.
>...sure steam might be fun and interesting, but i just don't see it having the
>economical _future_ of pv.
it's hard to imagine pv having anything other than an economical _future_.
>if i saw pv that same way -- simply as a hobby -- i'd sure be wasting my
>time and lots of money by dedicating years of my life almost exclusively
>to its study.
you will probably be able to find a job working on new pv technologies
that will result in amazing low prices, "just around the corner" :-)
>>how will people heat their houses in 40 years' time?
>i have two answers for the heating problem: (1) passive solar,
good idea. let's do it now. today. you can help. honest work...
>and (2) gas (natural gas reserves aren't projected to run out until well
>into the 22nd century, and it burns relatively clean).
it pollutes the air. and as you say, very little is needed for heating
efficient passive solar houses, eg superinsulated houses with thermally-
isolated low-thermal mass sunspaces.
>...somehow i doubt you'll see large institutions going back to the days
>of steam tunnels, unless there's no other option...
that sounds more like steam heating than electricity made from solar steam.
ursinus college just built a steam tunnel to heat the 47 buildings on its
campus from a central steam plant. they are planning to switch it from oil
to gas, and perhaps thinking of cogeneration, "just around the corner" :-)
>> >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.
>
>i'm having a great time with pvs right now, and i always hated all that
>carnot and brayton cycle crap! :-)
i'm glad you are having fun now, alan.
nick
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