Text 2181, 183 rader
Skriven 2006-06-08 11:45:00 av Robert E Starr JR (2627.babylon5)
Ärende: Re: Atheists: America's m
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* * * This message was from Charlie Edmondson to rec.arts.sf.tv.babylon5.m * *
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* * * and has been forwarded to you by Lord Time * * *
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Josh Hill wrote:
> On Tue, 6 Jun 2006 20:34:56 +0000 (UTC), Charlie Edmondson
> <edmondson@ieee.org> wrote:
>
>
>>Josh Hill wrote:
>>
>>
>>>We engineers are genuinely excited about it, because it gives every
>>>sign of doing just what it's supposed to -- serve as a pollution-free
>>>energy carrier and a virtually unlimited source of clean nuclear
>>>power.
>>>
>>
>>Hi Josh,
>>Sorry, you have bought into the hype, not the reality.
>>
>>Fuel cells ain't cheap, and with the present technologies, never will
>>be. Again, try to actually buy one, esp. one for a vehicle application.
>> If you ain't GM or the government, you ain't gonna even get a call
>>back from the sales agent!
>
>
> But that's because those fuel cells are still in the laboratory.
> They'll have to be mass produced for the price to come down.
>
> To put it in perspective, the fuel cells used by NASA in the 70's cost
> about $600,000 per kW. The price of fuel cells today is about $4,500
> per kW, a spectacular drop. SECA hopes to bring that down to $400 per
> kW by the end of the decade, and according to their website, GE and
> Delphi have already brought the costs of the stack down to $294 per kW
> and $254 per kW respectively:
>
> http://www.netl.doe.gov/seca/
>
> That's damn cheap! But you can't yet buy one at your local fuel cell
> shop.
>
>
>>All these great technology demonstrations, with a range of XXX miles,
>>are mainly marketing speak on those range estimates. The truth is,
>>batteries have a lot better energy storage density than even LH2, and is
>>a whole lot cheaper.
>
>
> The energy density of compressed H2 and if things pan out metal
> hydride storage is sufficient to give a fuel cell car range comparable
> to a gasoline vehicle. And fuel cell vehicles can be refilled like a
> conventional car, whereas battery-powered vehicles have to be
> recharged, which limits their effective range.
>
> Battery technology has been improving slowly in recent years, whereas
> fuel cell technology has been improving rapidly. So fuel cells are
> expected to become significantly cheaper than batteries within two or
> three years. Conversely, batteries are still too heavy and/or
> expensive to be the primary power source for a vehicle with the range,
> performance, reliability, and cost of a gasoline-powered car: as
> things stand, we're a few years away from even a practical plug-in
> hybrid. That equation may well change some day, but as things now
> stand it seems many years off.
>
> I wouldn't be surprised though if vehicles combine batteries and fuel
> cells, though, with the batteries used to store the energy from
> regenerative brakes and perhaps for local travel where their
> efficiency advantage outweighs their higher capacity cost.
>
> (Another way of looking at it: fuel cells are actually very similar to
> batteries, but since the fuel is supplied externally, they need only
> be sized to provide x kW, whereas (non-flow) batteries have to sized
> to store the energy. So fuel cells have an intrinsic cost advantage,
> which depending on specifics may or may not outweigh the efficiency
> advantage of batteries.)
>
>
>>And, using a long carbon chains to store the
>>hydrogen is better yet... 8-)
>
>
> Heh, yes, until the world melts and we get nuked by Iran . . .
>
>
>>And finally, you still gotta get the hydrogen in the first place. If
>>you have electricity from wind, nuke, or any other source, and you want
>>a car, use batteries. You don't want to waste 70% of it creating and
>>using hydrogen.
>
>
> No, but look at it this way:
>
> Midrange estimate of the cost of a gallon equivalent of hydrogen from
> wind: $2.20
>
> Estimate of the cost of a gallon equivalent of off-peak electricity
> from a battery charged from the grid (in a plug-in hybrid, but I'll
> assume the figure for all-electric cars is similar): $1.00
>
> So the power for the battery option is cheaper -- until you include
> the cost of the batteries! When you do, the battery option becomes
> more expensive for anything but local travel. (I'm assuming that both
> batteries and fuel cell technology continues at its current and
> projected rate.) Thus the economics favor the vehicle with a fuel
> cell, or, quite likely, a battery and a fuel cell.
>
> Also, the hydrogen could be made more cheaply from natural gas -- I've
> chosen the cleanest option, wind and electrolysis. To be truly fair,
> one would have to compare wind and electrolysis with wind and
> batteries, in which case one has the penalty of grid storage, which
> adds to the cost of the electricity.
>
>
>>By the way, all that 'market speak' about fuel cells being more
>>efficient than and ICE are just that, MS (i.e. BS!) They are basically
>>saying "We COULD be that efficient, some day blah blah blah" when in
>>reality, the actual difference, at theoretical best, would be like 2-5%,
>>and the ICEs are getting more efficient a lot faster than the fuel cells
>>are.
>
>
> Where did you get your figures? I found an article that purported to
> minimize the difference:
>
> http://www.evworld.com/view.cfm?section=article&storyid=730
>
> but at a first reading it makes at least two bad assumptions, one by
> comparing the highest efficiency ICE's with current fuel cells rather
> than those that will be produced, the other by assuming that the H2
> will be compressed rather than stored in hydrides.
>
>
>>Now, if you are talking going to high efficiency diesels, you have an
>>argument! You just can't buy them in California... :-(
>
>
> From what I've been reading, you'll be able to, eventually. And they'd
> be great with biodiesel. But I doubt that anyone's going to want to
> drive anything with an ICE once fuel cell cars hit the market -- hell,
> I suspect that would be true even if the fuel cell vehicles cost more,
> because they'll be more comfortable and stylish than anything on the
> road and they'll give your old sedan the performance of a Porsche . .
> ..
>
Hi Josh,
Guess we will just have to agree to disagree. You have been reading
propoganda produced by the proponents for hydrogen, and I have been
reading propoganda produced by the opponents, although mine was
generally written by engineers with engineering analysis, and the
pro-hydrogen pieces are typically written by professional writers
speaking to researchers - hype aplenty... 8-)
And, there are theoretical limits on the fuel cells and the
electrolysers, which we are a long way from even approaching. When we
get close, that will be when the fuel cells are 3-5% better than an ICE.
Beware when you hear someone talk about the efficiency of one part of
the system, such as just the fuel cell, and compare it to the entire
system, such as an ICE. Also, take care when they mention botton
cycling, and such 'efficiency boosters' as they will have little place
in vehicle applications. That is where you take the waste heat from the
unit, and use it for something else. Except for heating your car
interior in winter, there is little use for the waste heat in a mobile
application.
And take a better look at the reality of those metal hydride storage
tanks. The only place I have seriously seen them considered is in a
submarine, and even there, it is a demonstation vehicle. They weigh A
LOT, don't hold that much hydrogen, require high temperatures to
function, and are therefore a nice research project but have little hope
of being in your garage!
Also, you spoke of grid storage ADDING to the cost of electricity. Have
you seriously priced the alternatives? That $2 a gallon equivalent for
wind-h2 is serious fantasy. Really.
Charlie
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