Re: Hydrogen for cars

Dirk Bruere at NeoPax wrote:
Uncle Ben wrote:
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
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- 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.

The point is that a hydrogen infrastructure is a non-starter.
Even the optimists talk along the lines of "... by 2050..".
Meanwhile battery tech is coming on apace. It doesn't need to get much better before electric cars really become practical. Factor of two or three.


The real problem then becomes one of the capital costs of battery replacement for vehicles. Wait until most of the hybrids have been running a few years and those who bragged about their low costs for "fuel" have to lay out several thousand dollars for new batteries!
FK
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  • Re: Hydrogen for cars
    ... produce hydrogen from water at the point of use, so that the need for bulk ... Ultimately the sun is the only feasible source of energy that is independent ... of mineral resources, whether realised as heat, electricity or mechanical ... The point is that both effectiveness and efficiency have to be considered. ...
    (sci.chem)
  • Re: Electric vehicles, was Re: hey
    ... If the batteries you use to store the energy are lithium, you could get 99% efficiency in energy storage and extraction; with a good brushless motor at 90% efficiency, this gives ... Electricity is mostly generated by fossil fuels -- currently, coal for over 50% -- so I'd need the mining overhead, etc. ...
    (rec.arts.sf.composition)
  • Re: Hydrogen for cars
    ... produce hydrogen from water at the point of use, so that the need for bulk ... Ultimately the sun is the only feasible source of energy that is independent ... The point is that both effectiveness and efficiency have to be considered. ... Batteries, 90%+http://en.wikipedia.org/wiki/Lithium_ion_battery ...
    (sci.chem)
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