Re: Hydrogen car emits like a hummer

On 2008-08-26, Rowland McDonnell <real-address-in-sig@xxxxxxxxxxxxxxx> wrote:
Whiskers <catwheezel@xxxxxxxxxxxxx> wrote:

[snip]

When you take into account the costs and environmental damage involved in
making batteries, keeping them charged, and disposing of them when worn
out, electric cars (and 'hybrids') work out much less 'green' than
conventional petrol or diesel engined cars.

Last thing I heard, 80% of France's electricity was nuclear.

And how 'green' is 'nuclear'? Better than coal, oil, or gas, certainly,
but still producing a lot of heat (district heating schemes can't use all
of it, even if you can get people to accept nuclear power stations in the
middle of towns) - and the 'used' fuel is nasty stuff, even though it
doesn't take up anything like as much space as ash and soot. (I don't
anticipate people being eager to have houses built out of 'nuclear
bricks', but 'cinder blocks' seem to be perfectly acceptable).

There are industrial-scale schemes in development and pilot stages for
using microbes (various sorts, including genetically engineered) to
split water using sunlight as the energy source at much higher
efficiency than you get from normal plant photosynthesis.

We can already make methanol and 'bio-diesel' quite easily by mostly
biological means, and both can be used to drive fuel cells or
internal-combustion engines (bio-diesel can be used in existing standard
diesel engines with little or no modification - and it isn't all that hard
to make them run on freshly squeezed un-modified vegetable oil, which is
what Mr Diesel originally envisaged more than 100 years ago). I'd need
some convincing that hydrogen is 'better' than methanol as a fuel-cell
fuel.

I don't know how far advanced designs are for vegetable-oil driven fuel
cells, but they should be very efficient in theory.

The point about electric cars is that they're a way of doing it that
*can* be powered by non-carbon-emitting sources - whereas petrol powered
cars can't be.

Petrol cars could be modified to work on methanol, but they'd lose a lot of
power compared with petrol. Petrol/meths blends have been widely used
though - which helps, at least. 'Synthetic petrol' made from inedible
plant matter would be a big hit, if it cost no more than the fossil stuff.

The next step is to provide the non-carbon-emitting generated
electricity - or non-carbon-emitting generated hydrogen in the case of
hydrogen cars.

Their merit is that they
produce most of their pollution somewhere other than where they are used

Not just that: fossil fuel burning in a power station is a lot cleaner
and more efficient than fossil fuel burning in a car engine. And it's
straightforward to install fancy plant at a power station to capture any
emissions that your combustion process does liberate so you can put them
somewhere other than the atmosphere. That includes the carbon dioxide
emissions.

'Carbon capture' is a trick still being worked upon; I don't think
anyone's managed it outside a laboratory. But the principle behind
'carbon neutral biofuel' is perfectly sound, and works already so long as
people grow as much fuel as they use. (That's the tricky part).

(admittedly, the better efficiency of power station combustion compared
to car engines is cancelled out by losses in the electricity supply
chain. Diesel oil can be moved from place to place with no loss if your
tank has no leaks. Electrical power transmission involves losses all
over the place.)

And the diesel in my car's fuel tank can sit there for months without loss
or significant deterioration; try doing that with hydrogen - particularly
as a gas. And if someone squishes my car, all the fuel tank will do is
make an oily puddle, which is not what you get from a squished hydrogen
bottle.

(or at least 'out of town' in the case of a hybrid that spends most of its
time on the open road). Their financial attraction has a lot to do with
electricity not being taxed as vehicle fuel.

Yep.

Rowland.

For those of us with no off-street parking and living in the middle of
large towns, electric and 'hybrid' vehicles are not very practical no
matter how attractive they might seem. Even a conventional pedal cycle is
rather tricky to carry up stairs, without the added weight and bulk of
batteries and a reasonable motor; and I'm certainly not going to carry a
Prius up here! Methanol fuel cells would pretty much answer that problem,
if they worked well enough - but I'm not so keen on hydrogen.

--
-- ^^^^^^^^^^
-- Whiskers
-- ~~~~~~~~~~
.

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