Re: Solar-hydrogen home power system?

From: Gymmy Bob (nospamming_at_bite.me)
Date: 10/21/04 

Date: Wed, 20 Oct 2004 21:27:53 -0400

Sounds like a backpaddle for the "speak too soon foolish"

"Ray Drouillard" <cosmicpam2@comcast.net> wrote in message
news:2tofefF21iggsU1@uni-berlin.de...
>
> "Dan Bloomquist" <EXTRApublic21@lakeweb.com> wrote in message
> news:4176DEE2.2040003@lakeweb.com...
> >
> >
> > Ray Drouillard wrote:
> > >
> > >
> > > 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.
>
> 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:
> > > > This is it:
> > > > 41 percent (of delta 'G' of hydrogen oxidation to water vapour)
> > > > for the fuel cell spec'd at
> > > > http://www.ballard.com/resources/powergen/NexaSpec***.pdf .
> > > >
> > > > Raising specific power -- only 1.2 kW over 13 kg --
> > > > to levels adequate for a car prime mover drops the efficiency,
> > > > I guess, by a third. Then there are inverter and motor losses,
> > > > and we're down to 20 percent.
> >
> > 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.
>
>
> >
> > >
> > > 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.
>
> 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.
>
>
>
> >
> > >
> > > 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.
>
> 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.
>
>
> >
> > >
> > > 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.
>
> 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.
>
>
>
> > > 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.
>
> 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
>
>
>
> >
> > >
> > > Ray Drouillard
> >
> > Best, Dan.
> >
> > --
> > http://lakeweb.net
> > http://ReserveAnalyst.com
> > No EXTRA stuff for email.
> >
>
>