arnold@gatech.UUCP (Fred Fortran) (08/16/84)
I recieved the following in my mail earlier this week, and am only just now getting around to post it. He (or may be she, I don't know) makes a good point that hasn't been on the net yet (at least I haven't seen it yet...) This is the letter in its entirety, minus some irrelevant mail-header stuff. > From: dmcnh!gts@sii > Return-Path: <decvax!ittvax!sii!dmcnh!gts> > Date: Fri, 10 Aug 84 12:20:17 edt > Subject: Re: alternate, hopefully safe, energy sources (fusion) > References: <806@ihuxx.UUCP>, <9520@gatech.UUCP> > > I thought that liquid lithium would flow along the inside of the walls > of the fusion containment chamber. Not only does this absorb the neutrons > to prevent damage to the solid permanent walls, but in so doing, captures > the heat of the reaction and can be used as a heat transfer medium. > > Please try to get more information about this. I would post this idea > myself but I cannot post, I can only meddle (like this). Your mission, > if you decide to accept it, is to post the above idea for public ridicule. > Put the blame on: > The unposting mailbox of ><..!decvax!ittvax!sii!dmcnh!gts Well, I accepted the mission; here is the note. So it seems like maybe fusion might not be so bad. Of course, I have no idea how hard it is to get hold of enough liquid lithium. To paraphrase a famous physician of the 23rd century, "Damn it Jim, I'm a computer scientist, not a physicist!" :-) -- Arnold Robbins CSNET: arnold@gatech ARPA: arnold%gatech.csnet@csnet-relay.arpa UUCP: { akgua, allegra, hplabs, ihnp4 }!gatech!arnold Save the Arithmetic IF!
alcmist@ssc-vax.UUCP (08/20/84)
<harmful or fatal if swallowed> The subject is drawbacks of fusion power, specifically damage to reactor walls from high-energy neutrons. > From: dmcnh!gts@sii > Return-Path: <decvax!ittvax!sii!dmcnh!gts> > Date: Fri, 10 Aug 84 12:20:17 edt > Subject: Re: alternate, hopefully safe, energy sources (fusion) > References: <806@ihuxx.UUCP>, <9520@gatech.UUCP> > > I thought that liquid lithium would flow along the inside of the walls > of the fusion containment chamber. Not only does this absorb the neutrons > to prevent damage to the solid permanent walls, but in so doing, captures > the heat of the reaction and can be used as a heat transfer medium. The answer depends on the type of fusion reactor. They come in two flavors. A fusion reactor can hold its fuel in a more-or-less steady magnetic bottle, which is called magnetic confinement, or it can hit a pellet of fuel with high-energy lasers and hope a lot of energy is released before the pellet flies apart. That's called inertial confinement. In either kind of reactor, the main reason for having lithium is to breed more fusion fuel. When lithium is struck by neutrons from a fusion reaction, it turns into tritium, which can be used in the fusion reaction. (Tritium is an isotope of hydrogen ...) A magnetic-confinement reactor has to work in a vacuum, otherwise junk gets into the plasma and screws things up. Lithium inside the reaction chamber would evaporate and contaminate the plasma. In a magnetic-confinement reactor, the lithium would flow *outside* the wall of the reactor. An inertial-confinement reactor doesn't have the problem of needing a superclean vacuum. It could use jets of liquid lithium to absorb neutrons, breed fuel, transfer heat, and even absorb some of the shock from the explosions of fuel pellets. By the way, you really don't need tritium for a fusion reaction. It's just that the fusion between deuterium (naturally occurring and edible) and tritium (man-made and radioactive) is the easiest to start. Second generation fusion plants would probably use a reaction that throws off charged particles instead of neutrons. Doing so is a lot harder but would allow direct conversion to electricity. (There would also be less radioactive material to handle). Fred Wamsley -- UUCP:{ihnp4,tektronix}!uw-beaver!ssc-vax!alcmist ARPA:ssc-vax!alcmist@uw-beaver I am not speaking as a representative of the Boeing Company or any of its divisions. Opinions expressed are solely my own (if that) and have nothing to do with company policy or with the opinions of my coworkers, or those of the staff of the Software Support Center VAX.
sunny@sun.uucp (Sunny Kirsten) (08/23/84)
A Modest Proposal
I suggest a gravity-confined fusion reactor operating in a near-
perfect vacuum, insulated from us by 93 Million Miles of that vacuum, and
we ourselves insulated by a gravity-confined cloud of gasses (earth's
atmosphere) to absorb the high energy radiation from the fusion reactor,
and to absorb modest sized asteroids, comets, etc. Then let there be
fusion radiation energy collectors installed at points of need of energy.
Some of these may merely collect IR, for heating, some may collect visible
light for the generation of electricity. Some may collect advantageous
frequencies of light to assist in chemical reactions which store energy
to create food (photosynthesis). Fail Safe. Simple. Free. The reactor
and its insulator have been wisely provided for us, all we have to do is
build the collectors!
No Nukes! Turn OFF the SUN! What?!? (appologies to Pooh)
--
{ucbvax|decvax|ihnp4}!sun!sunny (Sunny Kirsten of Sun Microsystems)dmt@hocsl.UUCP (08/26/84)
REFERENCE: <1640@sun.uucp> OK. Somebody's got to be pulling my leg. A pro-SUN dialectic from SUNNY at SUN Microsystems? What do the laws of probability say about that? (Now I'm sorry I asked. We'll probably see two deeply reasoned probabilistic analyses, and five flames about the appropriateness of this posting.) Dave Tutelman
jbn@wdl1.UUCP (jbn ) (09/08/84)
A brief summary of the problems with alternative energy sources:
SOLAR POWER
PASSIVE HOUSE HEATING
Very feasible, if the house is designed with it in mind. You
still need a backup heating system, but it doesn't get used often.
SWIMMNG POOL HEATING
Best known application. That big pool of water is just what you
want for heat storage. Less popular since CA turned off the tax
incentive.
ACTIVE HOUSE HEATING / HOT WATER HEATING
Often useful. System must be engineered properly; there have been
bad designs that used more power to drive the pumps than the system
delivered as output. The heat storage problem is moderatly tough;
somewhere there needs to be a big tank of water, or rocks, or
something.
ACTIVE AIR CONDITIONING
It can be done, but usually isn't worth the trouble. One installation
that works is in the Santa Clara, CA, recreation center, a nice place
to visit during hot weather energy crunches. But there is a LOT of
machinery making it work.
PHOTOVOLTAICS
Coming along; up to 7-9% efficiency now. Still expensive, but may
get better. Useful for power in remote areas; my favorite is the
solar-powered fence charger for electric fences (see Sears Farm
and Ranch Catalog). The big problem remains batteries.
Kirby's photovoltaic system (Kirby is the inventor of the IC, and
works for (and owns a big piece of) Texas Instruments), seems
promising, but pumping hot hydrobromic acid around is not my idea
of appropriate technology for the home. (Sure you can make it work
with stainless steel pipe and 100% X-ray inspected welds, just like
the nuclear plants, but it costs). But maybe they will develop a
better chemistry.
WIND POWER
It now appears that medium-sized windmills (about 50' blade diameter)
are the best size; the giant units are down too much and the small ones
aren't worth the trouble. There are some really great tax incentives
to own a share of a wind farm in CA; see your broker (Merril Lynch
has a scheme) for details. But it isn't economic compared to
even oil power, and it only works when you have other sources to
take up the slack during low-wind periods. Again, the storage problem.
SMALL HYDRO
Efficient when producing, the problem is finding good sites. Plants
that produce juice only during spring runoff aren't enormously useful.
But if you can tap into a non-seasonal watercourse, you can have a
nice little power source, plus some extra income during peak periods.
WAVE POWER
This has been tried on and off for centuries; the elaborate mechanisms
with lots of floats and machinery keep breaking in storms and need lots
of maintenance. And again, sometimes there are no waves.
----------------
The basic problem with all these technologies is that none of them are
good base load power sources that you can rely on; all must be backed
up by some other technology. Even multiple units of the same
technology don't help; all the windmills stop in a calm. None of
these technologies can power an energy-intensive industry like, say,
aluminum refining, or even a large city. And when you add in the
cost of the energy storage facilities, these technologies look a
lot worse.
Personally, I like deep natural gas as an energy solution, followed by
fusion if we can ever make it work. Knowing that the SPS is possible
is nice in case we can't, but it seems like a lot of work just to get
an energy source. Fission power is too messy, and I don't really
approve of any reactor you can't just scram and walk away from.