"IMM" wrote in message
...

"The Natural Philosopher" wrote in message
...
IMM wrote:

"Franz Heymann" wrote in message
...

"The Natural Philosopher" wrote in message
...

Franz Heymann wrote:



So with a large area of Thermolux you might get to 200% more easily

than

with other panels?
Please, please understand that there is no such concept as
"efficiency

per

square foot" in either engineering or in physics. Efficiency is

usually

simply the ratio between the output power and the input power of a

system.


Actually that is not totally so. Efficency is a term that can be
applied
to more things than power.

For example, one could define the efficiency of a roof in terms of
the
amount of water that runs off versus the total amount that falls on
it.


One can define an efficient business as one that has the highest
sales
value, or margin value, per employee.

Efficiency is a measure of the efficacy against a theoretically
perfect
system,

That is the beginning of a circular argument.


of something doing the job it is designed to do. As normally
measured by how much it produces of the desired output versus how
much
input it needs.

If we for example take solar energy, it is not menaingful to say that
e.g. civering every roof in lonbdon with a .3% efficient solar panel
is
inefficient, if the cost of so doing would actually be less than
building and running an equivalent power station over the same .
timescales.

One could argue that in terms of various resources one or the other
is
more efficient.

The power station takes up less space, but uses more fossil fuel. The
electric panel is inefficient in overall thermodynamic terms, but
maybe
more efficient in the actual use of sunlight, since we don't have to
wait a couple of million years for the trees to turn back into
oil...The


power station has far less labour content involved, but perhaps uses
more materials.

uppose fo an instant that we cracked fusion power. Who cares about
efficiency, since the actual waste products - helium and heat - are
totally insignificant in a global context. At that point electcity
would
become the cheapest form of energy, subject to no taxes at all
probably,
and we would all be driving electric cars, and heating our houses
electrically, immediately :-)

Thanks for the homily.

I agree that in general usage, "efficiecy" is bandied around with gay
abandon. However, the discussion about solar panels was a
scientific/engineering one. To talk about "efficiency per unit area"
in
such a context is pure nonsense.


What balls!

I reserve a part of a roof of 20ft x 10ft, 200 squ foot. I put in
flat
plate collectors, I get n volume of solar heated hot water on a
certain
isolation at a certain time of year. I put in the same 200 squ foot
Thermomax solar collectors. I get n x 2 volume of hot water on the
same
isolation and certain time of year. For each squ foot of roof the
Themomax
is 100% more efficient. Is that clear?

I could use 400 squ foot of flat plate collector on the roof, twice
the
area, and produce the same volume of solar hot water as the Thermomax
solar
collectors which takes up half as much square footage.

The area is "very" important in this instant. Is that clear?

Yes, but efficiency is independent of that IMM.

Thats tantamount to saying a 5oKw boiler is twice as efficient as a 25Jw
one.

It is not. Solar collectors produce hot water. Some produce more than
others for the same area, hence more efficient for a given area.

No. Not more efficient for a given area. Just more efficient. The area is
irrelevant.
Some unkmeasured area of flat panel may produce 1 kW. The same area of
Thremomax may produce 2 kW. The thermomax is therefore twice as efficient
as the flat panel. The area you have used for doing the comparison is quite
irrelevant.

Franz

"IMM" wrote in message
...

"The Natural Philosopher" wrote in message
...
IMM wrote:

"Franz Heymann" wrote in message
...

"The Natural Philosopher" wrote in message
...

Franz Heymann wrote:



So with a large area of Thermolux you might get to 200% more easily

than

with other panels?
Please, please understand that there is no such concept as
"efficiency

per

square foot" in either engineering or in physics. Efficiency is

usually

simply the ratio between the output power and the input power of a

system.


Actually that is not totally so. Efficency is a term that can be
applied
to more things than power.

For example, one could define the efficiency of a roof in terms of
the
amount of water that runs off versus the total amount that falls on
it.


One can define an efficient business as one that has the highest
sales
value, or margin value, per employee.

Efficiency is a measure of the efficacy against a theoretically
perfect
system,

That is the beginning of a circular argument.


of something doing the job it is designed to do. As normally
measured by how much it produces of the desired output versus how
much
input it needs.

If we for example take solar energy, it is not menaingful to say that
e.g. civering every roof in lonbdon with a .3% efficient solar panel
is
inefficient, if the cost of so doing would actually be less than
building and running an equivalent power station over the same .
timescales.

One could argue that in terms of various resources one or the other
is
more efficient.

The power station takes up less space, but uses more fossil fuel. The
electric panel is inefficient in overall thermodynamic terms, but
maybe
more efficient in the actual use of sunlight, since we don't have to
wait a couple of million years for the trees to turn back into
oil...The


power station has far less labour content involved, but perhaps uses
more materials.

uppose fo an instant that we cracked fusion power. Who cares about
efficiency, since the actual waste products - helium and heat - are
totally insignificant in a global context. At that point electcity
would
become the cheapest form of energy, subject to no taxes at all
probably,
and we would all be driving electric cars, and heating our houses
electrically, immediately :-)

Thanks for the homily.

I agree that in general usage, "efficiecy" is bandied around with gay
abandon. However, the discussion about solar panels was a
scientific/engineering one. To talk about "efficiency per unit area"
in
such a context is pure nonsense.


What balls!

I reserve a part of a roof of 20ft x 10ft, 200 squ foot. I put in
flat
plate collectors, I get n volume of solar heated hot water on a
certain
isolation at a certain time of year. I put in the same 200 squ foot
Thermomax solar collectors. I get n x 2 volume of hot water on the
same
isolation and certain time of year. For each squ foot of roof the
Themomax
is 100% more efficient. Is that clear?

I could use 400 squ foot of flat plate collector on the roof, twice
the
area, and produce the same volume of solar hot water as the Thermomax
solar
collectors which takes up half as much square footage.

The area is "very" important in this instant. Is that clear?

Yes, but efficiency is independent of that IMM.

Thats tantamount to saying a 5oKw boiler is twice as efficient as a 25Jw
one.

It is not. Solar collectors produce hot water. Some produce more than
others for the same area, hence more efficient for a given area.

No. Not more efficient for a given area. Just more efficient. The area is
irrelevant.
Some unkmeasured area of flat panel may produce 1 kW. The same area of
Thremomax may produce 2 kW. The thermomax is therefore twice as efficient
as the flat panel. The area you have used for doing the comparison is quite
irrelevant.

Franz

"IMM" wrote in message
...

"The Natural Philosopher" wrote in message
...
IMM wrote:

"Franz Heymann" wrote in message
...

"The Natural Philosopher" wrote in message
...

Franz Heymann wrote:



So with a large area of Thermolux you might get to 200% more easily

than

with other panels?
Please, please understand that there is no such concept as
"efficiency

per

square foot" in either engineering or in physics. Efficiency is

usually

simply the ratio between the output power and the input power of a

system.


Actually that is not totally so. Efficency is a term that can be
applied
to more things than power.

For example, one could define the efficiency of a roof in terms of
the
amount of water that runs off versus the total amount that falls on
it.


One can define an efficient business as one that has the highest
sales
value, or margin value, per employee.

Efficiency is a measure of the efficacy against a theoretically
perfect
system,

That is the beginning of a circular argument.


of something doing the job it is designed to do. As normally
measured by how much it produces of the desired output versus how
much
input it needs.

If we for example take solar energy, it is not menaingful to say that
e.g. civering every roof in lonbdon with a .3% efficient solar panel
is
inefficient, if the cost of so doing would actually be less than
building and running an equivalent power station over the same .
timescales.

One could argue that in terms of various resources one or the other
is
more efficient.

The power station takes up less space, but uses more fossil fuel. The
electric panel is inefficient in overall thermodynamic terms, but
maybe
more efficient in the actual use of sunlight, since we don't have to
wait a couple of million years for the trees to turn back into
oil...The


power station has far less labour content involved, but perhaps uses
more materials.

uppose fo an instant that we cracked fusion power. Who cares about
efficiency, since the actual waste products - helium and heat - are
totally insignificant in a global context. At that point electcity
would
become the cheapest form of energy, subject to no taxes at all
probably,
and we would all be driving electric cars, and heating our houses
electrically, immediately :-)

Thanks for the homily.

I agree that in general usage, "efficiecy" is bandied around with gay
abandon. However, the discussion about solar panels was a
scientific/engineering one. To talk about "efficiency per unit area"
in
such a context is pure nonsense.


What balls!

I reserve a part of a roof of 20ft x 10ft, 200 squ foot. I put in
flat
plate collectors, I get n volume of solar heated hot water on a
certain
isolation at a certain time of year. I put in the same 200 squ foot
Thermomax solar collectors. I get n x 2 volume of hot water on the
same
isolation and certain time of year. For each squ foot of roof the
Themomax
is 100% more efficient. Is that clear?

I could use 400 squ foot of flat plate collector on the roof, twice
the
area, and produce the same volume of solar hot water as the Thermomax
solar
collectors which takes up half as much square footage.

The area is "very" important in this instant. Is that clear?

Yes, but efficiency is independent of that IMM.

Thats tantamount to saying a 5oKw boiler is twice as efficient as a 25Jw
one.

It is not. Solar collectors produce hot water. Some produce more than
others for the same area, hence more efficient for a given area.

No. Not more efficient for a given area. Just more efficient. The area is
irrelevant.
Some unkmeasured area of flat panel may produce 1 kW. The same area of
Thremomax may produce 2 kW. The thermomax is therefore twice as efficient
as the flat panel. The area you have used for doing the comparison is quite
irrelevant.

Franz

"IMM" wrote in message
...

[snip]

Technically Richard's right.
You keep switching your definitions.

[IMM says:]
I don't.

You do. You talk about "efficiency per square foot" and in the next line
you refuse to multiply the efficiency per sq ft by the area to obtain the
resultant efficiency.

[snip]

Franz

"IMM" wrote in message
...

"IMM" wrote in message
...

"RichardS" noaccess@invalid wrote in message
...
"IMM" wrote in message
...


I could use 400 squ foot of flat plate collector on the roof,
twice
the
area, and produce the same volume of solar hot water as the
Thermomax
solar
collectors which takes up half as much square footage.

The area is "very" important in this instant. Is that clear?

Yes, but efficiency is independent of that IMM.

Thats tantamount to saying a 5oKw boiler is twice as efficient as
a
25Jw
one.

It is not. Solar collectors produce hot water. Some produce more
than
others for the same area, hence more efficient for a given area.

No.

Efficiency is the ratio of converted power out to power in .

The area doesn't come into it.

In this case it does. Area is the most important factor as it is
limited
on
a roof. Solar panel X can be more efficient (ratio of converted power
out
to power in) than panel Y. But panel X may take up four times the area
of
panel Y. It means eff all if the area is not taken into account. For
a
given area which is the most efficient? Area, area, area.

Also, with solar panels the input doesn't really matter as you don't pay
for
it. The output per square foot, or metre (hot water generated), is what
matters. The efficiency of a boiler comes into the "ratio of converted
power out to power in", and is important as you pay for the fuel.

That was a trivial remark. Power transducers and transformers are usually
compared in terms of their efficiencies, amongst othe things

Franz

"IMM" wrote in message
...

"Franz Heymann" wrote in message
...

"The Natural Philosopher" wrote in message
...
Franz Heymann wrote:


So with a large area of Thermolux you might get to 200% more easily
than
with other panels?
Please, please understand that there is no such concept as
"efficiency
per
square foot" in either engineering or in physics. Efficiency is
usually
simply the ratio between the output power and the input power of a
system.



Actually that is not totally so. Efficency is a term that can be
applied
to more things than power.

For example, one could define the efficiency of a roof in terms of the
amount of water that runs off versus the total amount that falls on
it.


One can define an efficient business as one that has the highest sales
value, or margin value, per employee.

Efficiency is a measure of the efficacy against a theoretically
perfect
system,

That is the beginning of a circular argument.

of something doing the job it is designed to do. As normally
measured by how much it produces of the desired output versus how much
input it needs.

If we for example take solar energy, it is not menaingful to say that
e.g. civering every roof in lonbdon with a .3% efficient solar panel
is
inefficient, if the cost of so doing would actually be less than
building and running an equivalent power station over the same .
timescales.

One could argue that in terms of various resources one or the other is
more efficient.

The power station takes up less space, but uses more fossil fuel. The
electric panel is inefficient in overall thermodynamic terms, but
maybe
more efficient in the actual use of sunlight, since we don't have to
wait a couple of million years for the trees to turn back into
oil...The

power station has far less labour content involved, but perhaps uses
more materials.

uppose fo an instant that we cracked fusion power. Who cares about
efficiency, since the actual waste products - helium and heat - are
totally insignificant in a global context. At that point electcity
would
become the cheapest form of energy, subject to no taxes at all
probably,
and we would all be driving electric cars, and heating our houses
electrically, immediately :-)

Thanks for the homily.

I agree that in general usage, "efficiecy" is bandied around with gay
abandon. However, the discussion about solar panels was a
scientific/engineering one. To talk about "efficiency per unit area" in
such a context is pure nonsense.

What balls!

It is not balls at all. Two readers have tried to help you out of the
nonsense you have been speaking, but you appear not to have got the point at
all yet.
I reserve a part of a roof of 20ft x 10ft, 200 squ foot. I put in flat
plate collectors, I get n volume of solar heated hot water on a certain
isolation at a certain time of year. I put in the same 200 squ foot
Thermomax solar collectors. I get n x 2 volume of hot water on the same
isolation and certain time of year. For each squ foot of roof the
Themomax
is 100% more efficient. Is that clear?

Firstly, 100% of what?
Secondly, the number you quote is independent of the area of the panels,
the correct way of making the claim is to say quite simply "Thermomax panels
are twice as efficient as the flat plate units". That would be a precise
statement, incapable of being misunderstood than the incorrect way you have
been using for describing relative efficiencies.

Please believe me, an efficiency is only a ratio, and as such it is a
dimensionless quantity.
"Efficiency per square foot" is a meaningless concept, which can be misused
in the way I have now tried to show you at least four times.

I could use 400 squ foot of flat plate collector on the roof, twice the
area, and produce the same volume of solar hot water as the Thermomax
solar
collectors which takes up half as much square footage.

Absolutely correct. The Thermomax is twice as efficient as the flat panel.
You therefore need only half as much thermomax as flat plate to produce the
same power.

The area is "very" important in this instant. Is that clear?

As clear as daylight. The reason for the reduced area of Thermomax is that
it has twice the efficiency as the flat plate. *Not* that it has "twice the
efficiency per square foot".

Franz





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In message , IMM
writes

"Franz Heymann" wrote in message
...

The UK is aiming for 25% of its power generation by wind. CHP Stirling
boilers are also envisaged to fill gaps too.

CHP has its place in the right environment. But there are lots of
nimbys.


It would surprise me if they ever got that much wind power installed.

There is a mass installation programme right now, with much off it just
off-shore, out of sight and in direct line of wind.

Britain is the windiest country in Europe.

Though at the moment the emphasis seems to be entirely on installing
windmills and not on commissioning or operating them. The ones visible
along the A19 seem to be permanently feathered and non rotating. And
even if they were operating the wind doesn't blow continuously so you
still need backup conventional power stations for the cold windless
days.

But at least wind generation has more prospect of being useful than
solar power at our latitude and with the UK's cloudy maritime climate.

No. Just that other panels, such as Thermomax, are far higher per squ foot
area than a normal cheap flat plate.

Lashings of hot water on the few sunny days in mid summer, and horrid
technical problems in mid winter trying to keep the system from
freezing.

The technology and engineering is there, and it is improving by the month.
That is not the problem at all. It is educating the people about the new
technology and the will to push it through.

It is pretty hard to find applications where even the latest PV cells
are truly cost effective. You have to be a long way from any mains power
before their cost per watt justifies using them.

Solar power works reasonably at latitudes below about 45 degrees, but it
is quite frankly a complete non-starter at latitudes 55N and above.
Unless you count biomass conversion in forests for indirect fuel
generation.

Regards,
--
Martin Brown

"Franz Heymann" wrote in message
...

So with a large area of Thermolux you might get to 200% more easily than
with other panels?

I forget the figures, but they are much more efficient and generate hot
water at low solar levels.

Please, please understand that there is no such concept as "efficiency per
square foot" in either engineering or in physics. Efficiency is usually
simply the ratio between the output power and the input power of a system.

Output per squ foot then. A sq foot of Thermomax is ratio between input and
output, which is much more than the input output ratio of a squ foot of flat
panel. This means in a given area the Thermoxmax gives me more hot water
per square foot, which mean per square foot of area the Thermomax is more
efficient. This is a moot point.



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IMM wrote:


www.acpropulsion.com


This web site appears out off date. No press release for two years,
indicating no progress.




Eh? Last report was september 2003?

http://www.acpropulsion.com/ACP_Bib_results.pdf
"AC PROPULSION INC. Dedicated to Creating Electric Vehicles that People
Want to Drive
www.acpropulsion.com
September 29, 2003
San Francisco
FOR IMMEDIATE RELEASE
tzero Earns Highest Grade at 2003 Michelin Challenge Bibendum...."


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RichardS wrote:

"The Natural Philosopher" wrote in message
...

Dave Plowman wrote:


snip

Mmmm. I checked out some model plane electric motors. About a kilowatt
and 3/4 pound, so about 2bhp per pound. 200 brake horsepower for 100lb
weight anyone? and no gearbox or clutch? No wonder that electric Lithium
car at AC propulsion is gettin 0-60 times in under 4 seconds, and a 300
mile range...

They beat the fuel cell cars on everything at the tests.

www.acpropulsion.com




There are two problems with elecric motor vehicles that would have to be
overcome to make them viable.

First problem would be that they really need some kind of backup power. If
a conventional fuel vehicle (or indeed any fuel that can be quickly
recharged) runs out of or low on fuel then it is a quick and simple job to
put more in the tank. A battery powered vehicle would need some considerable
time recharging - either at the side of the road or at a recharge
point/"fuel" station.


Not really. A breakdown truck with a big battery can recharge it at
about 5 miles range per minute. If you run out of fuel anywhere you are
in for a wait of usually an hour or more before the AA gets there.

I don't see it as any different frankly. You don't let your car run out
of petrol, and you shouldne'ty let it run out of charge either.



Forget to put the thing on charge last night? You're
stuck in the morning.


Forget to fill up with petrol? Your stuck.

Power cut? Ditto.


Petrol strike? Ditto.

The occasional long journey?


Plan it with one hour stops every 300 miles. Forced breaks :-) You
shouldn't be driving more than 5 hours without a break anyway.




Forget it.

Second problem is one of recharge logistics.

Battery vehicles would represent a considerable advantage in towns and
cities. Quiet and pollution free at the point of use.

However, the majority of people living within large cities and towns do not
have designated parking spaces, and most of it is on-street parking.
Pavements would have to be dug up and publically accessible chargeing points
installed to be able to recharge such a vehicle, along with a suitable
payment mechanism. I can't see the LA taking too kindly to me stringing a
cable across the pavement to my house! Even in areas with controlled parking
zones there is no right to be able to park outside one's house, so the price
of someone parking in "my" space, abandoning a car or even leaving a skip
would be complete immobility for me. Visitors? Hmmm.


This IS a more curious and interestimg point, however for most urban
drivers, range is not a huge issue. They areusing the thing to go
shopping, or on other similar short trips. Actually I fill up every
couple of weeks for a 300 mile range tank, and I am in the country...if
you can't find somewhere tpo park the car - public car park etc - for an
hour or so every couple of weeks, that has a charge point..it might be
supermarket, underground car park or whatever. Easy enough to take a
pre-paid car and stick it in the slot, ane wire your car up to the
charger whilst you do the shopping.OK its not off peak...

...but in the end, in Canada they have on street electric points to plug
into to stop the cars freezing anyway. Something akin to a parking meter
with a plug is all it takes.





I'd have a battery powered vehicle at a sensible price and with decent
performance/range like a shot. But until these problems are solved, then
it's not viable.



I don;t see these as major problems frankly, as transition would be
slow. For example I know of a few places where LPG cars can fuel up now,
whereas a few years ago you bought your own gas and stuck it in the boot :-)

Even a ten minute stop at a charge station could net you 50 miles more
'fuel' in the 'tank'

For mne, right now, an electric 'shipping trolley' would be perfect to
replace the Punto. We don't use that car for distances.


--
Richard Sampson

email me at
richard at olifant d-ot co do-t uk

"The Natural Philosopher" wrote in message
...
RichardS wrote:

"The Natural Philosopher" wrote in message
...

Dave Plowman wrote:


snip

Mmmm. I checked out some model plane electric motors. About a kilowatt
and 3/4 pound, so about 2bhp per pound. 200 brake horsepower for 100lb
weight anyone? and no gearbox or clutch? No wonder that electric Lithium
car at AC propulsion is gettin 0-60 times in under 4 seconds, and a 300
mile range...

They beat the fuel cell cars on everything at the tests.

www.acpropulsion.com

This web site appears out off date. No press release for two years,
indicating no progress.


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