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Re: Solar-hydrogen home power system?

R

Ray Drouillard

Jan 1, 1970
0
Don Lancaster said:
It is interesting to try and buy an electrolysizer.
Chances are overwhelming they will not even tell you how much they
cost.

They're not that hard to make. I made one when I was a kid. I used
salt water, so I had some chlorine coming off of the oxygen electrode.
Eventually, the chlorine was gone, and I was using an NaOH solution in
my device.

But, making a unit for fun and amusement is not the same as trying to
make a unit that is optimized for efficiency.


Ray Drouillard
 
R

Ray Drouillard

Jan 1, 1970
0
Jim Logajan said:
I have an answer to your question to Ray Drouillard. You can actually
measure the efficiency of electrolysis with inexpensive equipment. The
following URL contains instructions on how you can perform the experiment
yourself:

http://www.nmsea.org/Curriculum/7_12/electrolysis/electrolysis.htm

Or you could always do a Google search for the keywords "efficiency" and
"electrolysis" or (gasp) go to a library and look it up.


Thanks for the link. I did the google thing, and didn't get what I was
looking for -- which is the efficiency of a real-life unit that has been
properly designed and could conceivably become available for sale.

Anyhow, I'll take a look at it when I go back on line. It's all an
amusing exercise for now because photovoltaics are way too expensive to
be used where grid power is cheaply available.


Ray Drouillard
 
H

Hatunen

Jan 1, 1970
0
Please don't feed the trolls. TLE is one of the sorta sane sounding
crackpots around here, that if you actually get him going, will go into
a spiel about some super-quantum physics that he is proposing that will
solve all of humanities ills. Since you have told him you are an actual
physicist, you will hopefully not have to go through that nonsense...

My goal is not to feed trolls. But whenever a ceackpot manages
to sound sort of reasonable I want to make sure that readers with
a bit less sophistication about the subject are not taken in, so
we don't end up with several crackpots.

In fact, the whole hydrogen thing does sound reasonable at first
encounter. The science is sound, although the engineering is not.
And I certainly want to scotch the notion that engineering
problems can always be overcome if we are just diligent enough.
Technical problems can frequently be overcome, but engineering is
a meld of technological considerations with cost considerations.

Many things CAN be done, but it may not pay to do them.

************* DAVE HATUNEN ([email protected]) *************
* Tucson Arizona, out where the cacti grow *
* My typos & mispellings are intentional copyright traps *
 
H

Hatunen

Jan 1, 1970
0
If you have cryogenic or compressed hydrogen, you still have less energy
density than the gasoline in your automobile.

Besides, if it's piped to your house like natural gas, it doesn't have
to be cooled or greatly compressed. All you need is better pipes.

LOTS better and lots more expensive, the cheaper materials
suffering hydrogen embrittlement. And, because the energy content
of hydrogen gas at any specified temperature and pressure is a
LOT lower than, say, natural gas, the pipe will have to be much
bigger in diameter and consequently much thicker-walled. Seals
are also a major headache with hydrogen; you don't want teh stuff
leaking into your house.



************* DAVE HATUNEN ([email protected]) *************
* Tucson Arizona, out where the cacti grow *
* My typos & mispellings are intentional copyright traps *
 
H

Hatunen

Jan 1, 1970
0
Yah, yah, yah... details abound.

Those pesky old details.
The embrittlement problem comes under the 'better pipes' category.

It also comes under the way lots more expensive category.
As far as a total rework of appliances -- well, that simply isn't
necessary. It's common around here to buy appliances that will run on
propane or methane depending on the size of the orifice that is
installed. To run all the appliances in our house on hydrogen, we would
need to change some piping, and some orifices (known by some as 'jets').
It wouldn't be trivial, but it wouldn't be much harder than changing
from propane to natural gas. It is certainly far from being a 'total
rework'.

It would actually be a lot more dfficult that changing from
propane to natural gas.
I am wondering what you are talking about with colorants and odorants.
Why do you want to color the hydrogen gas?

So that you can tell if it's leaking and accumulating in an
upstairs bedroom. Pretty much the same reason for adding an odor
to natural gas.
Also, why not use the same odorant that we currently use with propane and methane?

Why not? Why don't you research it and tell us whether it's
compatible with hydrogen? Unfortunately, hydrogen can leak from
small pores that won't pass the odorant, so that may nto be an
answer.


************* DAVE HATUNEN ([email protected]) *************
* Tucson Arizona, out where the cacti grow *
* My typos & mispellings are intentional copyright traps *
 
H

Hatunen

Jan 1, 1970
0
I'll tell you what. Give me a few details about this 'exergy', and I'll
try to figure it out.

You don't know how to Google?


************* DAVE HATUNEN ([email protected]) *************
* Tucson Arizona, out where the cacti grow *
* My typos & mispellings are intentional copyright traps *
 
H

Hatunen

Jan 1, 1970
0
Why do we keep switching from economic to engineering considerations and
back?

Because engineering is applied technology and science with
economic considerations.


************* DAVE HATUNEN ([email protected]) *************
* Tucson Arizona, out where the cacti grow *
* My typos & mispellings are intentional copyright traps *
 
D

Don W.

Jan 1, 1970
0
Don Lancaster said:
It is interesting to try and buy an electrolysizer.
Chances are overwhelming they will not even tell you how much they cost.

--
Many thanks,

Don Lancaster
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
voice: (928)428-4073 email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com

I once went pricing electrolyzers to learn whether or not I wanted to buy
one and store energy (from a waterfall) in the form of hydrogen. Only one
company was shameless enough to give me a price. It was a small
electrolyzer intended for laboratory applications and would have been much
too small for my application. Still, the price was $40,000.

Proton advertizes the 'RE' model as the one designed specifically for
storing renewable energy:
http://www.protonenergy.com/index.php/html/gasproducts/generators/files/Rev07_04-SlimJim.pdf

If anyone learns the price of this little electrolyzer, please publish it
here!

Don W.
 
D

Dan Bloomquist

Jan 1, 1970
0
Ray said:
40% Is a whole lot better than the "less than none" that Don Lancaster
keeps quoting. As a matter of fact, I'm beginning to believe that he
has the whole spiel stuck in a text file for quick addition to his
prose.

Capital cost needs to be considered. On the other hand, Mr. Lancaster
has wave his hands around about wind and PV being energy sinks. Past
research has shown otherwise.

I went and fetched Grahams post for you:
However, I don't agree to his 50% hit in the implementation. The EV side
of the power train can easily do 85-90% net. There are source to wheel
traction systems that run 90% to 97% over most of thier power/speed range.
I still want more details about that 40%. I'm hearing figures anywhere
between 60% and 90% for both electrolysis and fuel cells. Where is the
hard data?

Crunch the numbers for your self, on that PDF above for that mighty
pricey PEM unit, if you don't believe Graham.
Yes, I can google until I'm blue in the face and crippled
from carpel tunnels, but some of those quoting the efficiencies ought to
have real data somewhere.

If we have electrolysis going at 80% efficiency, and a 70% efficient
fuel cell (just to throw in some reasonable numbers). you have a total
efficiency of better than 50% (allowing for some modest storage losses).

Electricity to wheels. Electrolysis 80%, storage 90%, PEM 40%, vehicle
85%. So you net 25% of your electrical input. There are EVs in
production that net better than 50% now. Also, compare the capital cost.
Hydrogen, rough guess, will run some 5 to 8 times an EV commuter.
If you want to compress the hydrogen to store it, and if the energy cost
of that is significant, you can recover some of the energy by using an
'air engine' to decompress the hydrogen before it is fed into the fuel
cell.

Capital cost and energy density.
Also, in a solar energy system, you are going to be getting more energy
in the summer than in the winter. That means that you will be using the
fuel cell in the winter if your solar array is sized such that you need
to store power in the summer for use in the winter. In that case, the
heat that is generated by the fuel cell can be used to heat the house.
In that way, you can use 100% of the energy that you have stored in your
hydrogen tanks. Any inefficiencies end up heating the house, or maybe
even cooking the meals (depending on how 'retentive' you want to be when
designing the system)

It will never ever make sense to use hydrogen in a terrestrial
application. Just run some numbers and compare them to the alternatives
that are presently applied.
Certainly, the cost of photovoltaics makes the system uneconomical now.
But, this is rec.arts.sf.science, so speculation of future advances in
the art are definitely on topic.

Sure, we could see thin film at a buck a watt. Still not cheap. I've
been reading about it for years and I still don't see it happening.
If I could go out and buy a bunch of plastic sheeting that converts
light into electricity with an efficiency of about 8% for a few cents a
watt, what would I do with it? Putting it on the roof would be a good
start. Storing power in batteries short-term for use at night would
also be a good idea. In fact, I can save on the cost of an inverter if
I use a bunch of batteries in series and store it at 180V, then just use
some MOSFETs to generate a pseudo sine wave output -- no up-converting
switching regulator, no muss, no fuss.

As a past poster would say, 'If we only had some ham, we could have ham
and eggs, if we only had some eggs...'

Inverters are $.50/watt, off the shelf. No muss, no fuss.

Qusetion, why hydrogen?
Ray Drouillard

Best, Dan.
 
G

Gymmy Bob

Jan 1, 1970
0
WTF are you replying to?

Dan Bloomquist said:
I get it, feuding trolls. Objective thinking is out as long as the other
guy is wrong. Typical.

Best, Dan.
 
G

Gymmy Bob

Jan 1, 1970
0
Definitely you have a point but as Don said not right now until things
change.

Solar power is being sold as a hobby and a retirement investment right now
(new marketting angle they came up with). I consuder it a break even hobby
for myself but I don't see myself on the roof replacing a corroded power
connection when I am 85 yoa.
 
G

Gymmy Bob

Jan 1, 1970
0
I have, and the figures stand according to the latest car manufacturers
using the technique.
 
D

Dan Bloomquist

Jan 1, 1970
0
Gymmy said:
I have, and the figures stand according to the latest car manufacturers
using the technique.
Don't top post.
Don't use outlook for a newsreader.

You must be thinking of the PEM fuel cell. Commercial electrolysis
easily runs 75%. PEM electrolysis can run over 90%
trolling.

Best, Dan.
 
R

Ray Drouillard

Jan 1, 1970
0
Don Lancaster said:
This is all carefully explained in
http://www.tinaja.com/glib/energfun.pdf
Or http://www.tinaja.com/glib/hack64.pdf for a thermodynamics intro.

A reversible thermodynamic process kicks off zero unrecoverable low
grade heat.

Do you know of any?

If you go electricity ---> room heat ----> electricity, you get
virtually none of your electricity back because Carnot's Law prevents
even a theoretical low delta-T recovery of more than a percent or two.
Going electricity ---> hydrogen ---> electricity is considerably WORSE
than this today.

I don't think so. It looks like you can get somewhere between 25% and
75% back. I don't know what the theoretical limit is. We are not,
after all, working with a Carnot cycle engine.

Exergy is the measure of this fraction and thus the energy value. If you
can convert the present energy form into another and back again with
most of it left, you have high exergy. If not, you have low exergy or
(in the case of hydrogen) negative exergy.

In other words, it's jargon for 'efficiency', or maybe 'theorietically
achievable efficiency', depending on the context.

Exergy is also easily quantifiable. The Gibbs Free Energy is one
pre-amortization measure that applies to certain classes of fuels.

Why are you suddenly switching from engineering to economics. Exergy,
as you defined it above, is a scientific term, and has absolutely
nothing to do with economics.

The amortization directly enters into the recoverable energy fraction
you can get back.
If you get back two cents worth of electricity and the interest on the
system is three cents, you have a net energy sink and are destroying
gasoline.

What does gasoline have to do with it? We were talking about
electricity and hydrogen. Then, you toss in amoritization. Now, you're
talking about gasoline.

The equivalance between dollars and energy can be observed by the large
sign out front that says UNLEADED $1.97. Ultimately all of economics is
dictated by the underlying net energy sources.

Yes, if the price of gas goes up, the exergy of hydrogen goes down.
That is the beauty of exergy. It tracks the true costs of reversible
fraction recovery.

You had defined exergy as an intrinsic value. Now, you're defining it
as an extrinsic value. Please make up your mind.
 
D

Don Lancaster

Jan 1, 1970
0
According to this:
http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/35948.pdf
electrolyzers suitable for generating hydrogen for use in automobiles have
energy efficiencies ranging from 56% to 73%.

Where do you get YOUR figures?

Don W.

On which aisle of Wal-Mart are these electrolysizers found?

Energy efficiency, of course, is ridiculously higher than fully burdened
efficiency.

--
Many thanks,

Don Lancaster
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
voice: (928)428-4073 email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com
 
R

Ray Drouillard

Jan 1, 1970
0
Dan Bloomquist said:
Capital cost needs to be considered. On the other hand, Mr. Lancaster
has wave his hands around about wind and PV being energy sinks. Past
research has shown otherwise.

Capital cost is economics, not engineering.

Effeciency is engineering, not economics.

They can be related, but the person expressing that relationship needs
to be explicit.

I went and fetched Grahams post for you:

However, I don't agree to his 50% hit in the implementation. The EV side
of the power train can easily do 85-90% net. There are source to wheel
traction systems that run 90% to 97% over most of thier power/speed
range.

Agreed.

With 65%+ efficient fuel cells, and 90%+ motors, a vehicle can turn
hydrogen into motion very efficiently. The main bugaboo is storing the
stuff (an issue that has been debated hotly in this thread).

There are now 60%+ efficient methane-fuelled fuel cells. I know of none
that are commercially available, unfortunately. If they do become
available, they would be ideal for running an ev because the methane
storage technology already exists. It still isn't as energy dense as
gasoline, but it's a lot more dense than hydrogen. It also has the safe
ty advantage of dissapating and floating away in the unlikely event of a
pressure tank rupture.

Thirdly, it's a real fuel -- not something that is derived from a fuel.
It can be mined, or very easily created from biomass.

Crunch the numbers for your self, on that PDF above for that mighty
pricey PEM unit, if you don't believe Graham.
losses).

Electricity to wheels. Electrolysis 80%, storage 90%, PEM 40%, vehicle
85%. So you net 25% of your electrical input. There are EVs in
production that net better than 50% now. Also, compare the capital cost.
Hydrogen, rough guess, will run some 5 to 8 times an EV commuter.

It pretty well goes without saying that making hydrogen from grid
electricity is a no-win situation.

As far as comparing a hydrogen system to a battery system -- well, I
expect the battery system to win when you consider efficiency. The
biggest obstacle for EV transportation is the lousy range of even the
best vehicle. It would be worth it to some people to give up some
efficiency just to get more range.

Getting back to the original post, though -- he was talking about a
totally fixed application. The electricity --> hydrogen --> electricity
idea had occurred to me, too. I was pondering what to do with cheap
solar cells of those much-promised organic semiconductor cells become
available at a reasonable price. At the time, I lived in the city, and
was limited to the area of my (small) roof. Therefore, storage to pick
up the slack in the winter would be a necessity. Since we also had
natural gas piped in, I planned on generating any additional electricity
needed using a natural gas fuel cell. The waste heat would be used to
heat the house.

Now that we live on a nice ten acre parcel, I'm not nearly so limited
when it comes to the area that I can cover with solar cells. That makes
it more feasible to get enough area covered to produce a day's worth of
electricity on even the shortest day. That cuts the storage
requirements considerably -- both in quantity and time. Hydrogen
wouldn't be necessary at all.

Of course, all of the above depends greatly upon the much-promised cheap
solar cells, as well as the availability of relatively inexpensive fuel
cells.

Then, of course, there are things like inverters and/or DC appliances.
The ceiling fans would have to be ripped out and sold. I would also
have to find something to replace the compact fluorescent lamps that we
have used to replace almost every incandescent light in the house. I
would probably use regular red, yellow, green, and blue LEDs in fixtures
that allow the light to mix because that is more efficient than using
white LEDs (for very good quantum physics reasons).

Incidentally, the cheapest way to save energy right now is to replace
all your incandescent lights with fluorescent lighting. Soon, LED
lighting will be more available.

So, my next realistic step is to make a digester to turn organic garbage
into methane. I don't expect to find an affordable methane fuel cell
any time soon, so if I get more methane than I can burn in my appliances
and vehicles, I'll use it to fuel a standard CNG generater, and use the
waste heat to heat the house. Lots of research has to be done before
getting anywhere near that far, though.


Capital cost and energy density.


It will never ever make sense to use hydrogen in a terrestrial
application. Just run some numbers and compare them to the alternatives
that are presently applied.

I won't argue that point. Before I buy the equipment needed to
generate, store, and use hydrogen, I will build a big water tower and
use my excess energy to pump the water uphill, and use a turbine or
water wheel to get the energy back. As a bonus, I'll also have either a
swimming pool or a fishing pond.

I might argue with the people who are scared to death of hydrogen, or
those who say "less than zero", but I have already throught through the
hydrogen-as-a-fuel situation to have a good handle on what it would take
to make that practical. On a large scale, off-shore nuclear energy
would make it a good option. On a small scale, it would take a very
specific set of conditions to make it worthwhile.

Sure, we could see thin film at a buck a watt. Still not cheap. I've
been reading about it for years and I still don't see it happening.

I'm talking about organic semiconductors, which may very well be made
very cheaply. Still, I'll believe it when I see it. I'm hopeful, but
far from convinced.


As a past poster would say, 'If we only had some ham, we could have ham
and eggs, if we only had some eggs...'

Inverters are $.50/watt, off the shelf. No muss, no fuss.

They will probably be cheaper once electric cars come more into
production. Right now, high-power switching transistors and fast
high-power diodes keep the prices up.
Qusetion, why hydrogen?

Because it's cool?

Remember, I'm not advocating the hydrogen solution. I have thought it
through, and share the conclusion of some or the people I am arguing
with. I don't share their reasoning, however.


Ray Drouillard
 
D

Dan Bloomquist

Jan 1, 1970
0
Don said:
:




On which aisle of Wal-Mart are these electrolysizers found?

On the same aisle you find the petroleum refineries?

Best, Dan.
 

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