Re: Hydrogen for cars

On Jun 27, 2:47 am, "Ian Macmillan" <iand...@xxxxxxxxxx> wrote:
"Uncle Ben" <b...@xxxxxxxxxxx> wrote in message

news:ddb82064-f1ed-404b-88e8-af3b092f22f7@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Jun 25, 11:43 am, Dirk Bruere at NeoPax <dirk.bru...@xxxxxxxxx>
wrote:

Ian Macmillan wrote:
The main value of hydrogen is at its endpoint of use in a fuel cell. The
considerable difficulties of manufacture, storage, transport and safety
probably rule out its practical use in bulk, except as a political
boondoggle.

However, there are a variety of methods using chemical reactions that
could
produce hydrogen from water at the point of use, so that the need for
bulk
hydrogen is eliminated. A recent example uses aluminium amalgamated with
gallium, but similar schemes, some using iron, have been around for
thirty
years.

To produce hydrogen from water using electricity is very inefficient,
and
uses far more energy than can be recovered from the resulting hydrogen,
quite apart from the cost of handling the bulk product.

Ultimately the sun is the only feasible source of energy that is
independent
of mineral resources, whether realised as heat, electricity or
mechanical
power. Fusion power is, as always, potential.

Primary energy can be used to directly produce an energy carrier, such
as
hydrogen, but to use the energy to produce an intermediate stage may be
a
more practical approach.

A chemical disassociation system could be even less energy efficient
than
electrolysis, but could be easily and safely distributed, perhaps in a
cartridge form.

The point is that both effectiveness and efficiency have to be
considered.

Is anyone able to put some figures on the potential cost efficiency of a
chemical dissociation system at the point of use, versus the bulk
production and distribution of hydrogen, as promoted by our beloved
leaders?

And how would the bulk and weight versus range of a water dissociating
car
system likely to compare with bulk hydrogen, or batteries?

Hydrogen for transport is a non-starter.
Splitting water, 80% efficient.
Fuel cell to electricity, 60% in

practicehttp://en.wikipedia.org/wiki/Fuel_cell#Fuel_cell_efficiency



Batteries, 90%+http://en.wikipedia.org/wiki/Lithium_ion_battery

--
Dirk

http://www.transcendence.me.uk/-Transcendence UK
Remote Viewing classes in London- Hide quoted text -

- Show quoted text -

The efficiency figures need further description.  For example,
conversion of the chemical energy in gasoline to motion of a car
against friction is only about 20%.  So 60% sounds pretty good. But
I'll bet that is not the process with 60% efficiency.

Ben

The thing about batteries is not their efficiency or capacity, but their
cost, and that as with explosives, the energy is all together in one place.
More so with super capacitors. A 30KWH battery is more dangerous than a
tankfull of petrol, which needs  air to burn. A capacitor with that much
energy would be a bomb! (remember the SF "Interociters"?)

Efficiency may take second place to something that works.

All the best
Ian Macmillan

It is correct that issue is cost. Technically electric car batteries
are already
sufficient (as demonstrated by plug-in Prius conversions or recent
Tesla roadster).
But cost is _even more_ a problem with Fuel Cells. This should be
obvious considering
massive amount of Pt etc catalyst needed to adsorb oxigen from the
air, complexity
of overall system (pumps, fans, condensers, water management, hydrogen
storage or
catalytic conversion etc).
The fact that fuel cells are extremely expensive
is hidden because there are no practical fuel cells available to
purchase!
Try "pricegrabber" - you will find only books.
With advanced batteries, you can go and purchase them, 18650 Li-ion
with 3.7V average and 2.2Ah in bulk for 2$/cell - about 4 Wh/dollar.
Looking for price per power - this cell is rated for continuous
discharge
at 1h rate (full discharge in 1hr), so about 8W per cell, 4W/dollar.

These are small cylindrical cells used in laptops. If mass produced
in
large size prismatic format, this indeed can go down because we save
on casing.

But with fuel-cells, all that are available for cost estimates are
experimental prototypes that cost millions. The mantra is that "once
we get to mass production, than...". But fuel cell has been around for
the same time as battery, and so it is already highly optimized. Also
fixed cost of noble metals is not going to go away. If we look for
rare examples of commercially available fuel cells:
http://www.computerworld.com/securitytopics/security/recovery/story/0,10801,102480,00.html
we can see price of 30kW (stationary backup) system for 100 000$. To
make it compact, lightweight and possible to fit into a car will
likely increase the price 10 times. But even with the stationary one
currently on sale we get 0.3W / dollar. That is 13 times more
expensive than battery!

Regards,
Yevgen
.

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