On Jun 6, 2009, at 7:37 PM, thomas malloy wrote:
Vortexians;
We have previously discussed the subject of hydrogen storage and
utilization.
Ammonia is an important method of energy storage in itself, and a
possible intermediate product of the silicon method of renewable
energy storage See:
http://www.mtaonline.net/~hheffner/BigPicture.pdf
The principle problems of dealing with ammonia are (1) the
requirement for complex large volume chemical plants to achieve
economies of scale, and (2) materials handling safety.
Industry has already handled these problems on large scale as the
annual production of ammonia is about 150 million tons. It is not at
all clear this can be handled economically or safely on a small
scale, especially in personal vehicles which can crash.
I'm writing to solicit your opinions on this technology. http://
www.apolloenergysystems.com/ publications.
Unless I missed something, there is insufficient information on this
site to make any kind of determination of the economic viability of
the technology.
Their plan is to recharge the cobalt lead battery, which, AFAIK is
a variant of the lead acid battery, with the ammonia fuel cell.
Where does it say the fuel cell takes in ammonia, and not hydrogen?
The specs seem to indicate an ammonia cracker or natural gas cracker
is required:
http://www.apolloenergysystems.com/_pdfs/APP_Model_101B.pdf
When I wrote the "Big Picture" essay referenced above, it did not
appear any commercial ammonia fuel cell was in sight.
The literature says that this battery has an energy storage
capacity in KW / KG comparable to a Li ion or a Ni hydride battery,
at 20 to 25 cents on the dollar. I'm excited by this, and have
suggested that they start marketing them.
What I'd like to discuss is the carbon footprint and the cost
effectiveness of recharging the battery by : A plugging it into the
grid, or B : using anhydrous ammonia to power the fuel cell. AFAIK,
the production of anhydrous ammonia requires prying N2 apart. As I
recall, this requires 14K calories per mol, which is one reason
that NO3 based explosives work so well. I don't see where that
energy is harvested, so the cracker should get real hot.
Cracking ammonia to make hydrogen *requires* energy (about 15 kJ per
gram of hydrogen), and (economically) runs at a high pressure and
temperature (in large chemical plants) using a catalyst:
N2 + 3 H2 <--> 2 NH3
However you can get about 9 times that energy back back when the
hydrogen is oxidized. The problem is cracking the ammonia cheaply and
safely on a small scale. It is not mentioned how this is achieved.
I would want to visit an actual pilot operation and see the
economics, etc. before investing, if investing were my objective.
Otherwise, this could just be a lot of hot air. Note that the date
on the "MARS Report" is 1968.
Nocera's method (developed at MIT) looks to be much more efficient
and down scalable, and a very strong competitor to the above.
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
