On 11/6/2003, David Maddern wrote:
Thanks. I was under the impression that most (all?) of these fuel
cells needed to have their fuels processed to provide H2 to the cell
as they were basically hydrogen fuel cells. (But there's lots of H2
in most organic compounds.) Still, if one can achieve efficiencies
greater than that of an internal combustion engine, it is a net win.
Tamara Kelly replied:
Lots of (expensive) boats have them.
And a friend of a friend installs them to outback homes when the cost of a
whisper gen is considerably less than getting the power connected.
I saw one on display at the last boatshow and was fairly impressed with
what it could do.
John Winckle stated:
Someone on another line claimed that the US nuke subs use stirling engines because of lack of noise.
and:
I would like to see more about whisper gen. Stirling engines have very limited power output.
Tamara Kelly answered:
You're on the Gold Coast aren't you?
Unfortunately you missed the last boat show - get to it next year at
Sanctuary Cove. I'm pretty sure they'll be showing it again.
Do a google on it - there is a fair amount of info out there.
In the thread "Watertanks and Taxis" on 4/8/2006, Anthony Morton wrote:
On 4/8/2006, at 6:03 AM, Anthony Morton wrote:
I agree with you WRT roads. I disagree with you to some extent on
electrical power distribution and completely with regard to
telecommunications. (As someone intimately involved in the design and
development of the Internet I do have a bit of experience in this
area.)
I grant your depth of experience here, but I also note the current
state of the Internet backbone in the US, which can fairly be said is
an oligopoly of a handful of telcos that have just prevailed on the
Congress for the right to discriminate in service provision according
to different types of traffic. From my vantage point the loss of
'network neutrality' seems to be a strategy by the telcos to help their
big-business mates with deep pockets at the expense of 1990s-style
entrepreneurs with new ideas but little capital.
Ah, democracy. The "democratic" infringement on the rights of the
minority by the majority. But that is a topic for another discussion.
(Is there a connection between economic theories and science? I would
have said 'no' but I don't really know.)
In a desperate attempt to stay on topic, I recall that the classical
economists of the 19th century who came up with the concept of general
equilibrium models imagined themselves to be developing a quantitative
science of human economic behaviour on a par with Newtonian mechanics.
At least one commentator has described this whimsically as 'physics
envy'.
The idea of democracy revolted Plato and his philosophical descendants,
who much preferred absolute monarchy or oligarchy to avert the spectre
of mob rule. But ultimately a political compromise is needed between
the infringement on the rights of the minority by the majority and the
infringement on the rights of the majority by the minority. Without it
all you generally get is the latter, with results like the Irish potato
famine.
As for electrical power, I can install PV panels, a wind-powered
generator, or my own combustion-powered generator. (Waste-heat powered
Stirling generator anyone? Heat from solar is easier to come by than
electrons.) I think that the presumption that a public utility is
always going to be somehow better than individual solutions is not
necessarily correct.
I don't think the presumption is necessarily correct either. The point
I was making was that decisions in a free market are biased toward the
individual solution, and in cases where there is a collective solution
that is more efficient, free markets often fail to find it. There are
other cases where the individual solution really is more efficient, but
they're not the ones I was highlighting because they are non-problems
for a free market approach.
The market has chosen the automobile over public transport, at least
until you get to some cost point where people then feel that the
flexibility is no longer worth the cost. I think the market will drive
that decision.
But one can hardly fail to notice that governments, and not markets,
have spent the last half century spending vast sums of money on roads
while shutting down public transport networks. So the individual's
choice of cars over public transport is hardly made on a level playing
field.
Perhaps. You seem to have forgotten that there is no driving force
toward innovation and improvement of service in a regulated monopoly.
That's why I'm not in favour of regulated private monopolies - I prefer
public enterprises with a strong service culture. A surprising number
of innovations have come out of Australia's public utilities in the
last century.
Then another cab operator would drive to the same schedule but turn
up a minute earlier still, thus poaching the passengers that the
first cab operator presumed to poach from the tram.
Which is the point at which the smart operator would begin to look at
alternate routes for people or offering customized services to
differentiate themselves. The smart ones would survive and the
not-so-smart would not.
That's the theory, and Melbourne's experience in the 1920s and 1930s
provides an empirical test of that theory. (Still trying to stay on
topic here by appealing to scientific method!) What the cab operators
ought to have done according to theory is innovate, and start running
cross-town routes to grow new markets outside the radial suburb-to-city
routes provided by the tram operator, or at least start up services on
other radial routes that didn't have tram lines. In practice though
that's not what happened: the cab operators went after the tram
operators' passengers, succeeded for a while, and then shut up shop
when the competition became too much to bear.
Melbourne might be the best empirical example we have of a free market
in public transport in a first-world city, because it's just about the
only such city that didn't regulate mini-bus operators out of existence
when they emerged after World War I. I've not seen any other
experiment in para-transit succeed in attracting significant patronage
in a large urban area with high car ownership. The systems that have
succeeded, funnily enough, are the centrally-planned ones in Europe and
Canada.
Do you really think that the markets are sufficient similar that the
same models apply? The roadway system is necessary for a functioning
economy. You *must* have it and it does drive the economy for *all*
people. I don't see public transportation in the same vein.
Less than one-tenth of the road system's function is moving goods: most
of it is moving people, just like a public transport system. The
paradox is that the passenger function of the road system induces
congestion which interferes with its economic function of shifting
freight. Thanks to the laws of economic equilibrium as noted half a
century ago by the economist Anthony Downs, the level of service on the
roads will always tend to deteriorate until it matches the level of
service of the public transport alternative. So improving the quality
of public transport will tend to improve road traffic conditions (and
the efficiency of freight transport) even if nothing is done to the
road system. That the standard of public transport really matters to
the economy is a seldom appreciated fact.
Brian Lloyd answered:
I agree with you WRT roads. I disagree with you to some extent on
electrical power distribution and completely with regard to
telecommunications. (As someone intimately involved in the design
and development of the Internet I do have a bit of experience in
this area.)
I grant your depth of experience here, but I also note the current
state of the Internet backbone in the US, which can fairly be said
is an oligopoly of a handful of telcos that have just prevailed on
the Congress for the right to discriminate in service provision
according to different types of traffic. From my vantage point the
loss of 'network neutrality' seems to be a strategy by the telcos
to help their big-business mates with deep pockets at the expense
of 1990s-style entrepreneurs with new ideas but little capital.
And this is where I tend to part ways with many of my network
brethren. First off, and speaking technically, traffic shaping is a
fact of life. It is the only way to ensure that some applications
work on moderately loaded networks as it is the only way to control
latency jitter and guarantee bandwidth. You can't get away with it.
(If you use a VoIP service your router does traffic shaping to ensure
that voice packets have guaranteed bandwidth and latency so that you
don't experience drop-outs.)
That being said, it is interesting to understand *why* someone might
want to be able to charge to prioritize traffic. It saves them money
by allowing them to defer network upgrades. What happens shortly
thereafter is all lower tier customers abandon their network to move
to the network that offers "network neutrality" and excess backbone
capacity. It will become a marketing plus. The providers who decide
to play games will get burned by the market. The customers will vote
with their wallets. No government intervention needed.
Once you start the Internet down the slippery slope of regulation,
you can count on squelched innovation.
And, BTW, a "down" vote on "network neutrality" is not a vote for
tiered service, it is a vote against regulation. The market will do a
good job of sorting this out. It always has.
Ah, democracy. The "democratic" infringement on the rights of the
minority by the majority. But that is a topic for another discussion.
(Is there a connection between economic theories and science? I
would have said 'no' but I don't really know.)
In a desperate attempt to stay on topic,
Yes, as a matter of fact, I do ramble. Why do you ask? :-)
I recall that the classical economists of the 19th century who came
up with the concept of general equilibrium models imagined
themselves to be developing a quantitative science of human
economic behaviour on a par with Newtonian mechanics. At least one
commentator has described this whimsically as 'physics envy'.
The idea of democracy revolted Plato and his philosophical
descendants, who much preferred absolute monarchy or oligarchy to
avert the spectre of mob rule. But ultimately a political
compromise is needed between the infringement on the rights of the
minority by the majority and the infringement on the rights of the
majority by the minority. Without it all you generally get is the
latter, with results like the Irish potato famine.
I still think that the US Constitution is a good idea with the
exception of the two-party system. At least it makes an attempt to
build protection for individual rights into the system. Too bad it is
going away. Is it better there? I would really like to find a better
place to live than this one.
"The United States is a terrible place ... except for everywhere else."
As for electrical power, I can install PV panels, a wind-powered
generator, or my own combustion-powered generator. (Waste-heat
powered Stirling generator anyone? Heat from solar is easier to
come by than electrons.) I think that the presumption that a
public utility is always going to be somehow better than
individual solutions is not necessarily correct.
I don't think the presumption is necessarily correct either. The
point I was making was that decisions in a free market are biased
toward the individual solution, and in cases where there is a
collective solution that is more efficient, free markets often fail
to find it.
I suspect you are right. But given the choice of one or the other,
free market economics seems to work better in the long run.
Everything is a compromise.
There are other cases where the individual solution really is more
efficient, but they're not the ones I was highlighting because they
are non-problems for a free market approach.
The market has chosen the automobile over public transport, at
least until you get to some cost point where people then feel that
the flexibility is no longer worth the cost. I think the market
will drive that decision.
But one can hardly fail to notice that governments, and not
markets, have spent the last half century spending vast sums of
money on roads while shutting down public transport networks. So
the individual's choice of cars over public transport is hardly
made on a level playing field.
Which is more flexible to meet future needs: the public road system
or public transportation? The geographic social and economic centers
change with time. When an area begins to be too desirable (and
expensive) you get begin to get natural diffusion. With a general
ability to move goods anywhere and good telecommunications, you can
do business just about anywhere. I would really like to see the
public roadway system continue.
Perhaps. You seem to have forgotten that there is no driving force
toward innovation and improvement of service in a regulated monopoly.
That's why I'm not in favour of regulated private monopolies - I
prefer public enterprises with a strong service culture.
For better or worse, I think I can count on greed more than altruism
as a motivating force. It would be nice to think that people have the
welfare of their fellow men at heart but I fear it really isn't so.
A surprising number of innovations have come out of Australia's
public utilities in the last century.
Then another cab operator would drive to the same schedule but
turn up a minute earlier still, thus poaching the passengers that
the first cab operator presumed to poach from the tram.
Which is the point at which the smart operator would begin to look
at alternate routes for people or offering customized services to
differentiate themselves. The smart ones would survive and the not-
so-smart would not.
That's the theory, and Melbourne's experience in the 1920s and
1930s provides an empirical test of that theory. (Still trying to
stay on topic here by appealing to scientific method!) What the
cab operators ought to have done according to theory is innovate,
and start running cross-town routes to grow new markets outside the
radial suburb-to-city routes provided by the tram operator, or at
least start up services on other radial routes that didn't have
tram lines. In practice though that's not what happened: the cab
operators went after the tram operators' passengers, succeeded for
a while, and then shut up shop when the competition became too much
to bear.
Not surprising. Most people don't think too hard about problems ...
to their detriment.
Melbourne might be the best empirical example we have of a free
market in public transport in a first-world city, because it's just
about the only such city that didn't regulate mini-bus operators
out of existence when they emerged after World War I. I've not
seen any other experiment in para-transit succeed in attracting
significant patronage in a large urban area with high car
ownership. The systems that have succeeded, funnily enough, are
the centrally-planned ones in Europe and Canada.
Do you really think that the markets are sufficient similar that
the same models apply? The roadway system is necessary for a
functioning economy. You *must* have it and it does drive the
economy for *all* people. I don't see public transportation in the
same vein.
Less than one-tenth of the road system's function is moving goods:
most of it is moving people, just like a public transport system.
And the moving of people almost always involves commerce. We have
people going to the store to buy goods, going to centers of
entertainment, going to work, etc. Public transit gains efficiency by
optimizing certain routes at the expense of others. Also, public
transit rarely goes where I want to go so I rarely use it. (Well, St.
Thomas was a special case but there just weren't that many places to
go.)
Another way of looking at it is that the highway system is both
necessary AND sufficient.
The paradox is that the passenger function of the road system
induces congestion which interferes with its economic function of
shifting freight. Thanks to the laws of economic equilibrium as
noted half a century ago by the economist Anthony Downs, the level
of service on the roads will always tend to deteriorate until it
matches the level of service of the public transport alternative.
So improving the quality of public transport will tend to improve
road traffic conditions (and the efficiency of freight transport)
even if nothing is done to the road system. That the standard of
public transport really matters to the economy is a seldom
appreciated fact.
Interesting concept. I have never thought of it that way. I can see
in my own behavior that you may be right on this. Well, until you
can't get there by public transport.
And, yes, I agree; this has nothing to do with science. Time to get
back to that.
Anyone want to talk about nuclear decay?
Anthony Morton replied:
But the busses never run to my home or to my office. They run
nearby and they rarely go from home to office. The difference is,
packets don't care how far they have to travel but I do. Every
application, and in this case I am an application, has a bandwidth
requirement and a latency requirement. The latency of public
transportation is usually annoying AND it suffers powerfully from
what is known in the telecomm industry as, "the last mile
problem." With data I can solve the problem with point-to-point
microwave. That doesn't work for people.
True, there really is nowhere in California (except possibly within
San Fran city limits) where public transport is remotely close to
forming a useable network. Fortunately, there are networks
elsewhere that succeed in attracting many users - many of them in
cities without the huge population densities of Paris or New York.
The last-mile problem for telecomms must once have seemed
insurmountable too.
I did live in Washington, DC, and made sure I was within comfortable
walking distance of the Metro. I used Metro extensively as it was a
lot cheaper than driving.
But that was a very special case in my life where I was lucky enough
to manage to place my home and my work very near the Metro. When my
employment changed there was no convenient public transport so I
bicycled. It was only about 15KM each way so it was quite easy to do
if one didn't mind mixing it up with traffic during rush hour. In
downtown DC I learned to sprint between traffic lights and keep up
with both the flow and acceleration of the automobiles. I would
occupy a lane meant for a car and that prevented me from being pushed
off the road by an unthinking driver.
Once my commute exceeded 15KM using an automobile became necessary.
PV cells, eh? What is the theoretical limit of efficiency? I have
never looked. I know that best current practice is about 18% for
single-crystal silicon PV cells. I have heard of people making
thinner wafers and putting a reflective backing on so that photons
that make it through the substrate are reflected back to give them
a second chance to knock the odd electron loose. I am not sure
that improves efficiency but it reduces material and increases
fabrication cost. I need more information.
Actually, the real economic driver for PV cells is not efficiency
at all, but material requirements. Particularly here in Australia,
there is no shortage of real estate on which to put solar
collectors but a real shortage of PV cells of any efficiency that
don't involve a high energy cost in silicon production, not to
mention a high cost in dollar terms.
Ah, it is good you recognize that part of the problem. Most people
advocating the use of PV as a power panacea do not recognize the
energy costs and the relatively toxic waste products from
fabrication. As far as I can tell, there is no fix for this on the
horizon.
(And I still think that PV is just cool and fun to play with. I have
never gotten over building my first PV-powered electric motor and
using it to propel a model boat back in the mid 1960's.)
The technology that will succeed here is the one that produces the
most electricity from the least silicon, no matter how many watts
per square metre it captures.
In the near to medium term however, I'd place my bets with solar
thermal technology.
Ah, it seems we are thinking along the same lines.
That at least has the attraction of not requiring fancy materials
with high-energy production processes.
A stirling-powered alternator at the prime focus of a tracking
collector is a possibility. There were some interesting hermetically-
sealed stirling-powered alternators designed to convert waste heat of
any sort into electricity. Think about waste incineration, solar,
geothermal, etc.
I think that free-piston Stirling-cycle alternators have real
potential but they are still too far up the cost curve. The cost of
easy energy is going to have to go up first.
But tracking cylindrical collectors should be able to make steam. We
understand steam power generation just fine.
Brian Lloyd responded:
But the busses never run to my home or to my office. They run
nearby and they rarely go from home to office. The difference is,
packets don't care how far they have to travel but I do. Every
application, and in this case I am an application, has a bandwidth
requirement and a latency requirement. The latency of public
transportation is usually annoying AND it suffers powerfully from
what is known in the telecomm industry as, "the last mile
problem." With data I can solve the problem with point-to-point
microwave. That doesn't work for people.
True, there really is nowhere in California (except possibly within
San Fran city limits) where public transport is remotely close to
forming a useable network. Fortunately, there are networks
elsewhere that succeed in attracting many users - many of them in
cities without the huge population densities of Paris or New York.
The last-mile problem for telecomms must once have seemed
insurmountable too.
I did live in Washington, DC, and made sure I was within comfortable
walking distance of the Metro. I used Metro extensively as it was a
lot cheaper than driving.
But that was a very special case in my life where I was lucky enough
to manage to place my home and my work very near the Metro. When my
employment changed there was no convenient public transport so I
bicycled. It was only about 15KM each way so it was quite easy to do
if one didn't mind mixing it up with traffic during rush hour. In
downtown DC I learned to sprint between traffic lights and keep up
with both the flow and acceleration of the automobiles. I would
occupy a lane meant for a car and that prevented me from being pushed
off the road by an unthinking driver.
Once my commute exceeded 15KM using an automobile became necessary.
PV cells, eh? What is the theoretical limit of efficiency? I have
never looked. I know that best current practice is about 18% for
single-crystal silicon PV cells. I have heard of people making
thinner wafers and putting a reflective backing on so that photons
that make it through the substrate are reflected back to give them
a second chance to knock the odd electron loose. I am not sure
that improves efficiency but it reduces material and increases
fabrication cost. I need more information.
Actually, the real economic driver for PV cells is not efficiency
at all, but material requirements. Particularly here in Australia,
there is no shortage of real estate on which to put solar
collectors but a real shortage of PV cells of any efficiency that
don't involve a high energy cost in silicon production, not to
mention a high cost in dollar terms.
Ah, it is good you recognize that part of the problem. Most people
advocating the use of PV as a power panacea do not recognize the
energy costs and the relatively toxic waste products from
fabrication. As far as I can tell, there is no fix for this on the
horizon.
(And I still think that PV is just cool and fun to play with. I have
never gotten over building my first PV-powered electric motor and
using it to propel a model boat back in the mid 1960's.)
The technology that will succeed here is the one that produces the
most electricity from the least silicon, no matter how many watts
per square metre it captures.
In the near to medium term however, I'd place my bets with solar
thermal technology.
Ah, it seems we are thinking along the same lines.
That at least has the attraction of not requiring fancy materials
with high-energy production processes.
A stirling-powered alternator at the prime focus of a tracking
collector is a possibility. There were some interesting hermetically-
sealed stirling-powered alternators designed to convert waste heat of
any sort into electricity. Think about waste incineration, solar,
geothermal, etc.
I think that free-piston Stirling-cycle alternators have real
potential but they are still too far up the cost curve. The cost of
easy energy is going to have to go up first.
But tracking cylindrical collectors should be able to make steam. We
understand steam power generation just fine.
and:
These folks seem to be making sealed free-piston stirling-cycle
generators for thermal applications. I don't think they are geared
for production applications. It strikes me that if someone made a
useful take-it-out-of-the-box-and-use-it generator they might make
some progress.
http://www.sunpower.com/index.php?pg=48
and:
But that was a very special case in my life where I was lucky
enough to manage to place my home and my work very near the Metro.
When my employment changed there was no convenient public
transport so I bicycled [.....] Once my commute exceeded 15KM
using an automobile became necessary.
This illustrates quite well, through a negative example, the
difference between having a super-duper service on some isolated
routes and having a real network.
I agree.
A positive example is Toronto ca.1990: back then their subway had
very modest coverage, and yet around a quarter of all trips in the
wider Metro Toronto region were made by public transport. It
turned out that while 80% of people in the area had no subway
access but only buses, the buses actually ran at reasonable
frequencies, were fast and comfortable, and connected into a
network using the main road grid. As a result, the Toronto
Transportation Commission recovered a higher proportion of its
costs than most other North American transit authorities. Without
this network formed by the buses, public transport use in Toronto
would have been about one-fifth what it was.
Interesting. It would be nice if all public agencies ran efficiently.
But tracking cylindrical collectors should be able to make steam.
We understand steam power generation just fine.
That's the thrust of the major lines of research we've got in
Australia currently. I think there's still a technical debate over
whether it's better to use parabolic cylinders focussing on a steam
pipe, or paraboloidal dishes focussing on a small boiler.
In terms of ease of fabrication, I like the cylindrical collector
focusing on a steam pipe. The pipe is the equitoral axis so you only
need to rotate on one axis. I have actually considered building one
just to play with. Do you have any suggestions for making a good
black-body?
The little stirling engines run up to about 36% thermal efficiency.
That is almost double the efficiency of the best single-crystal PV
cells.
Dishes tend to be more difficult to fabricate as you have to create a
curve in two dimensions. Mounts tend to be both heavier and more
complex.
and:
On Aug 12, 2006, at 10:43 AM, John Winckle wrote:
Brian
Recently I asked what 'free piston' meant in relation to hot air
engines. So
far no answer, can you help,TIA.
Sorry, I remember that but was in a hurry to go off and then forgot
to reply.
As I understand it, in most Stirling cycle engines both pistons are
mechanically linked together using some sort of eccentric or
pantograph linkage in order to get the necessary out-of-phase motion.
In the free-piston Stirling cycle engine, pressure differential is
used to move one of the pistons so it is "free" and not connected to
anything. The other piston transfer (or receives) power linearly.
This allows the free piston to be made in interesting ways, e.g.
liquid, a diaphragm, etc. Since there are no side loads the power
piston can run on an air bearing formed by the working fluid and
therefore have no wear.
Normally the free piston stirling cycle engine is used for cooling,
using a linear motor to input mechanical energy which results the
engine functioning as a heat pump. I understand that this may be used
to produce very efficient refrigerators, a significant consumer of
electrical power.
The Stirling cycle is reversible so the linear motor may be replaced
by a linear alternator and the flow of heat used to make the
mechanical energy needed to actuate the alternator.
The Wikipedia entry on Stirling engines has a reference to the book,
_Free_Piston_Stirling_Cycle_Engines_, by G. Walker. I guess I need to
pick that up and read it in order to gain a better understanding.
and:
http://www.stirlingengine.com/
I think I feel a science unit on Stirling engines coming on. What an
interesting way to teach the relationship between temperature and
pressure in a gas.
and:
On Aug 13, 2006, at 11:29 AM, John Winckle wrote:
Thanks Brian
I had got as far as sunpower but still can't visualise a free piston
working.
I found their web site to be somewhat annoying as well. It is a
wonder why some companies bother to have web sites as they seem to be
free of any content and/or information.
Here is a good site. Scroll down until you come to the description of
the Sunpower four-cylinder free-piston stirling engine.
http://www.ent.ohiou.edu/~urieli/stirling/engines/engines.html
and:
On Aug 18, 2006, at 3:05 PM, Toby Fiander wrote:
Brian Lloyd - was it something I said??
Sorry Toby, you didn't scare me away. I have been flying across the
US of A in my airplane, stopping at various places, picking up bits
of the family and dropping them off along the way. I just didn't feel
like extricating my laptop from where it ended up buried in the aft
baggage compartment.
As I fly across this rather large piece of the Earth visiting
exciting places such as Donaldsonville, Georgia; Liberty, Texas;
Amarillo, Texas; Wellington, Texas (nothing like the Capital of NZ
BTW); Laramie, Wyoming; Kemmerer, Wyoming (excellent digs for amateur
paleontologists), and Boise, Idaho; I never cease to be amazed at
this country I live in. No travelogue can do it justice. The key is
to avoid the big cities on the left and right coasts.
Regardless, I landed back at home after a 2.5 month hiatus. All
should be in order again.
We will be moving into our newly-purchased house on the airpark in
about a week. I know I am going to have to replace the air
conditioning system so I am investigating replacing the old one run
by mains power with a solar-powered absorption system. Waste heat can
provide domestic hot water. I am going to see if I can also use the
waste heat to provide electric power with a stirling engine. No rest
for the wicked.
Oh, and I have to plan the 4th-7th grade science classes. (No eighth-
year students this year.) I plan to kick off the "science fair"
projects early on so I can help them focus on doing science well
rather than on something flashy. OTOH, I will probably drag in the
robot ladybird beetle with infra-red guidance system I built 40 years
ago to explain the difference between "science" and "engineering".
My son and I were discussing how to incorporate disassembling and
reassembling a lawn-mower engine and then adding an automotive
alternator to create an electric power generation system into the
curriculum. Amateur radio, stirling engines, wire, electric lamps,
and batteries figure in there somewhere, as do model rockets.
Hopefully I can find a way to keep everyone interested through the 4-
year curriculum.
Toby Fiander wrote:
Sorry, Brian... I was wondering whether we might have had to send out search
parties. It is not completely unknown.
Until I visited the USA, I could not have believed the superlatives that
people speak of it.
I am going to see if I can also use the waste heat to provide electric
power with a stirling engine. No rest for the wicked.
Can you tell us about your Stirling-engine airconditioning when you get it
working? I have been very bad, too, but I mostly spend my time trying to
make enough to pay the wages.
The Sydney Girls High School science fair is a ripper and there are others
which some attend who are on here. Science Fairs are a great way to have
fun and learn science.
PS. I am pleased that Wellington, Texas is nothing like the one in New
Zealand. It is probably nothing like the one in South Africa, either. And
given even half a chance I would rather be in the one in South Africa, the
only country on earth that makes better wine than Australia.
PSS. Nice to see your smiling face again.
Brian Lloyd replied:
Well, I got into a rather long discussion with Brent Van Arsdale,
owner and proprietor of The American Stirling Company (http://www.stirlingengine.com). (I wrote some email with questions and I
guess I piqued his interest as he called me on the phone about 2
hours later.) He suggested that for solar use I investigate using an
ammonia/water absorption system rather than a Stirling heat pump.
Seems there are some people starting to build those. The most notable
seems to be Broad Air Conditioning, a company out of the PRC. (http://www.broad.com). They seem to have production solar and waste-heat
powered absorption air conditioning systems. Given that A/C is the
bulk of power consumption in summer, and you need A/C when the
insolation is greatest, the match to solar seems natural.
So, I would end up with all this heat collection to power the A/C. In
winter I would still have heat collection but no need to power the A/
C so I can use it directly for space heat. What's left over I can use
for domestic hot water. (I love a good long hot bath.) If I have any
heat left over after that I might be able to get a little stirling
engine to produce some electrical power.
The Sydney Girls High School science fair is a ripper and there are
others which some attend who are on here. Science Fairs are a
great way to have fun and learn science.
I have always loved science fairs. (My little IR-guided ladybug won
the California State Science Fair in 1967 for 7th and 8th grade
physical sciences. I built an NMR spectrometer a year later and
repeated the result.) The problem is getting kids to do real science
or real engineering. Most just copy something out of a book but never
manage to really learn anything about how science is done. This last
year most kids just copied something out of a book of science
projects. That didn't seem very useful to me. My focus will not be
on the complexity or "flashiness" of a project but in how well they
do the science and identify problems with their methods. So I intend
to start early so they can think about what they want to do and how
to do it.
The hard part will be to find something that interests each child. I
always liked the physical sciences and engineering more than the
biological sciences but that is just me. Hopefully with enough time I
can help each child find the right project for them.
and in the thread "Alternate Energy - Heating and Cooling the Lloyd Abode"
Some of you may recall my comments about alternate energy and my
search for a way to heat and cool my new[ly renovated old] house. The
standing approach these days seems to be to slap some PV panels on
the roof and claim to be green. I questioned the efficacy of that
approach based on the low efficiency of PV panels (typically around
18% for panels using square-cut single-crystal PV cells). This led me
to look at systems that operated solely on thermal energy.
My first thought was to look at stirling cycle machines, both for the
conversion of lower temperature heat into electricity and to
mechanical work to power a heat-pump. Someone better versed in
stirling engines than I suggested that I spend more time looking into
absorption chillers. After some searching I found Yazaki Energy
Systems. They produce water-fired chillers as small as 10-ton
capacity (120,000 btu/hr). These chillers derate pretty well if you
need less cooling capacity. Since my needs are in the 3.5-5 ton
range, this seemed promising.
One of the issues of the water-fired chiller is that, even though the
heat input requirement varies substantially, the *quality* of the
heat (input temperature and temperature differential) must be held
relatively constant. The result was that the switching and control
systems were starting to get very complex. I was looking at taking
the hot water right off the collectors into the chiller and
controlling the flow rate to ensure that the chiller saw an input of
90C water as much of the time as possible regardless of how much heat
was required. If I was producing more heat than I was using I had to
shunt the increased flow from the collectors into my storage but I
had to use multiple small storages so that I could quickly heat them
to around 100C. If I filled all my storage to 100% capacity (100C
water), then I had to dump heat. First place I was going to dump heat
was into the swimming pool. After that was full I had to dump into my
cooling tower (that dumped the heat from the cool side of the
chiller). Yes, this was looking quite complex. (I think well-working
complex process control systems are very cool to implement in
software but I am also smart enough to know when they don't make
sense in the grand scheme of things.)
I don't like complexity in mission-critical systems. Complex systems
tend to be less reliable. So I decided to do my homework and go back
and reexamine the PV approach. What I found is that the newer air-air
heat pumps have SEER ratings well above 15. (SEER is the ratio of
heat moved to power input.) When looked at as a system, even with PV
efficiencies of 18%, the electrical solution is more efficient
overall. I can get by with less collector area to do the PV/heat-pump
system than I could with the water-fired chiller even though my
energy collection system would be a LOT more efficient for solar-
thermal. The side point is that I can use the electricity to do other
things besides just heat and cool my home. (I will probably retrofit
a solar space heating system as that doesn't have the complex
requirements of the water-fired chiller.) I like flexibility.
BTW, there is an ideal use for the water-fired chiller -- in a
cogeneration plant. IC engines tend to use a cooling loop running at
about 85C, right in the center of the operating point for the
chiller. Waste heat that would normally get dumped overboard can
provide the cooling requirements without having to steal any of the
mechanical energy from the engine. All of that mechanical energy can
be turned into electricity to do real work (as opposed to just
keeping things cool). This would make a LOT of sense in places where
it is inconvenient to use PV or wind power.
Time to go help my son with the hot-lunch program at school. I hope
[all of] you have a pleasant evening.
