Big diesel eta
Graham Cowan
made me recall that a leading fuel cell developer
reports a hydrogen consumption for its 1.2-kW PEM fuel cell
that works out to 41 percent efficiency
(http://www.ballard.com/pdfs/power%20gen/NEXASPECSHEET-FINAL-APR5_6.1.1.PDF).
They don't divulge hydrogen consumption for
another of their fuel cells of much higher power
(http://www.ballard.com/pdfs/transportation/MK902SPECSHEET-FINAL-APR5_4.1.1.1.PDF),
suggesting higher power means much lower conversion efficiency
-- which we know, but perhaps we wouldn't believe
*how much* lower if they told us.
But can't a big diesel easily beat 41 percent?
At http://www.manbw.dk/documents/L2131_brochure1.pdf ,
the answer: yes, by a few points.
And maybe some satisfaction for Mr. Don Widders,
if as I seem to recall it is he who was searching for
a primary source for the mythic 60-percent-efficient marine
diesel. It is most unlikely there is any such animal.
For this one, they tell you grams of fuel per shaft kWh,
plus what the lube oil pump takes, plus what water pumps
take, but not how many such pumps there are! I guessed 3,
and that meant per kWh 188.2 g of (LHV) 42.7-MJ/kg fuel.
That's 44.8 percent. Recalling that high-power PEM fuel
cells score an unknown but very substantial amount
less than 41 percent, we see that
even if there were hydrogen wells,
hydrogen fuel cell locomotives would be loco-losers.
--- Graham Cowan
http://www.eagle.ca/~gcowan/boron_blast.html --
a good way for cars to gain nuclear cachet
Don Widders
news:3D4977CD...@eagle.ca...
Thank you Graham! I'm not yet convinced the 60% engine doesn't exist. It
was my impression that 60% is not a PRACTICAL figure, but a figure achieved
in a very large lab engine. Others have told me that 60% is beyond
theoretical limits, but they also limited compression to something like 12
to 1. Anyway, I won't be talking about 60% efficient diesel engines anymore
unless I see it with my own eyes!
Don W.
Graham Cowan
> >
> > --- Graham Cowan
> > http://www.eagle.ca/~gcowan/boron_blast.html --
> > a good way for cars to gain nuclear cachet
>
> Thank you Graham! I'm not yet convinced the 60% engine doesn't exist. It
> was my impression that 60% is not a PRACTICAL figure, but a figure achieved
> in a very large lab engine. Others have told me that 60% is beyond
> theoretical limits, but they also limited compression to something like 12
> to 1. Anyway, I won't be talking about 60% efficient diesel engines anymore
> unless I see it with my own eyes!
I'm told that what might have happened is some
diesel outfit's publicist thought, hmm,
400 K exhaust, fuel-air charge peak T 1,600 K,
that means Carnot efficiency 75 percent.
Out of that theoretical max, what we get, 0.45,
is actually 60 percent.
If the meaning of "efficiency" in this context
has been debased in that manner, it would explain
why the MAN page doesn't use it, instead scrupulously
giving exact units of MJ in and kWh out.
> > ... 44.8 percent. Recalling that high-power PEM fuel
Steve Spence
--
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"Graham Cowan" <gco...@eagle.ca> wrote in message
news:3D4977CD...@eagle.ca...
Harry Conover
> made me recall that a leading fuel cell developer
> reports a hydrogen consumption for its 1.2-kW PEM fuel cell
> that works out to 41 percent efficiency
[snip good citations]
Graham, what actually surprises me is the very limited amount of
attention that Ballard and others are giving to what is arguably the
largest real market in practical co-generation: Fixed, small
commercial and industrial users.
In my area (Eastern Massachusetts) arguably 15% of the new commercial
and industrial installations emply natural gas fueled co-generation
facilities, where electricity, heating and air conditioning are all
supplied by the same system.
Typically these employ a gas fueled IC engine driving both an electric
generator and freon compressor, which supply the electrical, lighting,
heating and air conditioning needs for the facility...one which is
isolated from the rather frequent electrical power outages and
brown-outs experienced here, plus is less expensive to operate.
Most of these installations are in operation 24-hours/365-days, hence
are usually duplicate, redundant systems. (Maintenance is done on
one, while the other is carrying the load.)
Perhaps my thinking is twisted, but it would occur to me that this
well established co-generation market should be the first to be
addressed by the fuel-cell/electric motor technology, if it is indeed
a viable technology. The accumulated wear on a IC piston engine (or in
rare cases a turbine) should be a 'No Brainer' to be replaced by an
electric motor, provided that fuel cells exist that can 'cut the
mustard' in powering the electric motor driving these systems.
After some pause for thought, one has to ask the question: "Why aren't
the fuel cell firms like Ballard more aggressively pursuing this
existing market, rather than attempting to creat an entirely new one
with the bus?"
The fact that existing markets are not being address by the major fuel
cell firms suggests that their products are not viable when fueled by
anthing but hydrogen, which in itself is not a readily avaialable and
viable fuel source.
Worse still, that government subsidies/funding are the sole basis for
the existance of these activities, as well as some of the firms
themselves.
Given that there is an existing 'clear and present need' for a
mechanism more efficient (read reduced operating expense and
maintenance free) than an IC engine in co-generation systems, why
isn't this need being more aggressively and visibly addressed?
Just curious.
Harry C.