Re: Solar-hydrogen home power system?

From: Dan Bloomquist (EXTRApublic21_at_lakeweb.com)
Date: 10/21/04 

Date: Thu, 21 Oct 2004 01:55:54 GMT

Ray Drouillard wrote:
> "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.

Those PEM auto prototypes are running $80k+ at production levels. If we
can't afford them...

>
> Effeciency is engineering, not economics.

If you only get 5% of the heating value of coal to the wheels of a car,
what does that fuel cost? What infrastructure? It does all count. If it
were not about cost, we could cover a little spec of desert with solar
thermal and stop using coal for electricity.

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

Don's copy and paste library is a bit limited. :)

>
>>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.

I've been an advocate of methane powered SOFC, with a possible bottom
cycle for the heat, for years. But we would have to stop wasting methane
on peakers and get Canada to expand production.

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

There are no currently viable bio sources. Angiosperms and Gymnosperms
don't grow rapidly enough to be meaningful. Cultivated algae could work
in principle. But if it costs like solar...

>
>>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.

I don't think 2 to 3 times the efficiency is just 'some'. So many of our
miles are just to get to work and back, short trips. Hell, if those
commuter miles where done in civics and with car pooling, it would have
a dramatic effect on our consumption.

>
> 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.

If I can someday buy a 2Kw SOFC unit for around a grand, I'd do it
without thinking because I've already run the numbers. If you bottom
SOFC into home heating, you are getting 60% high grade electrical energy
and pushing 97% overall efficiency.

>
> 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.

If you are off the grid, you will likely do what most folks I know off
the grid do. Go on an electrical energy diet while on the batteries. Use
a generator for short periods of heavy load. Use PV to supplement the
charge on your batteries. And you go on that diet because PV/batteries
means your electricity runs around $.35-$.45/kwh if you figure a twenty
year lifetime on the equipment.

>
> 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).

Inverters are cheap and efficient. With CFs you don't have to live in
the dark. I've lived off grid and found kerosene lamps pleasant.

>
> 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.

Most of mine are CF, it is just silly to buy incandescence. $12 an eight
pack at Costco. And, modern CFs don't have a problem with the cold, they
just start a little slower.

>
> 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.
>
>>
>>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.

Check the efficiency of the system first. Remember that your electricity
is precious. Batteries may be the way to go.

>
> 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.

Even if you have to put in hundreds of miles of super conduction
transmission, pumped storage would win hands down because of the loss
and capital expenditures of hydrogen.

>
>
>>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.

It is all about the numbers. If they don't add up, they don't add up.

> Ray Drouillard

Best, Dan.

P.S. Get a good newsreader if you plan to spend any time on usenet.
Outlook makes a mess of the threads. I like Netscape well enough. 

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