Ah-hah! You have fallen straight into the trap! Electrolysers to produce
hydrogen MUST work 24/7 to achieve their rated efficiency, so what
happens when the wind drops or the sub goes behind a cloud? You have to
wait a week for full efficiency to be restored. The solar/wind systems
must therefore be backed up by conventional generation, such as
polluting coal or nuclear.
Then, just imagine that all the cars in the USA, in 20 years were
running on hydrogen into fuel cells (yes, it needs a vivid imagination,
as there isn't nearly enough platinum in the world to catalyse those
fuel cells), have you thought how much electricity would be required to
electrolyse the hydrogen and how much fresh water? Well, you would have
to more than double and less than triple ALL the present generation and
grid capacity, assuming the cars were of modest size (no Hummers or
SUVs). The 2002 installed production capacity is 848.3 GW. Let's take a
round figure of 1200 GW of new capacity for electrolysis. An average
state-of-the-art wind turbine of 3 MW capacity runs at an average of 12%
capacity in a suitable windy position onshore or 15% offshore. Let's be
optimistic and say the average real-time capacity is 0.6 MW, to allow
for technological advances. To generate enough H2 to run all those
hypothetical cars would therefore require 1200 x 1000/0.6, so you would
need 2,000,000 such wind turbines, all backed up by an equivalent
capacity of conventional power (coal, gas or nuclear) for when the wind
stops blowing. Solar? A typical efficiency is 150 W/mē. If installed in
the sunniest spot of the US (NM desert), this extra capacity would
require 1200 x 1000/(150 x 1E-6) mē of panels = 8 trillion mē at, say
$100 each (the present price is ~$300/mē, but I'm allowing for economy
of scale), without installation costs. Of course, this assumes the sun
will shine 24/7/52, which is slightly far-fetched. Now, 8,000 kmē of
panels requires roughly 2.5 times the space of horizontal surface to
avoid shadowing and to allow access for maintenance etc, so we need
20,000 kmē of land. Not counting the land for access roads, power
distribution and so on, this is about 1/15th of the whole of NM. This
would be quite a monumental achievement.
The overall cost of producing hydrogen per unit energy produced from
wind/solar, when used, is roughly 20-30 times that of burning gasoline
or diesel. So, if today's price for a gallon of gas is $2, you will be
paying $40-60 for the equivalent amount of propulsive energy with your
fuel cell car. It is a pipe-dream. (I agree, it is a lot cheaper
producing hydrogen from natural gas, but the supplies are limited, as
the US is already a net importer, and to do would involve massive
emissions of CO2, which is inadmissible.)
So please come down to earth.
Finally, this link is relative to the small island on which I live, but
the arguments are the same: http://www.cypenv.org/Files/hydrogen.htm -
you will find a number of other pages which may be of interest.
Brian
Brooks,Bill wrote:
> Hydrogen can be made by separating it from water leaving the 2 components, 2
> molecules of Hydrogen and one molecule of oxygen.
> This process is called electrolysis...
>
> http://www.nmsea.org/Curriculum/7_12/electrolysis/electrolysis.htm
>
> It can be done without pollution at all... using solar or wind power.
>
> Best regards,
>
> Bill Brooks - KG6VVP
> PCB Design Engineer , C.I.D.+, C.I.I.
> Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
> e-mail:[log in to unmask]
> http://www.dtwc.com
> http://pcbwizards.com
>
> -----Original Message-----
> From: Brian Ellis [mailto:[log in to unmask]]
> Sent: Friday, December 17, 2004 4:13 AM
> To: [log in to unmask]
> Subject: Re: [TN] DI Water
>
> And, please, tell me how you are going to produce hydrogen in sufficient
> purity and quantity to run a relatively low-efficiency device like a
> fuel cell? AND ensure that there is no pollution in the process? The
> much-vaunted fuel cell for, e.g., large-scale car use can never be. It
> is being developed purely as a magnet for governmental funding.
>
> If you wish to discuss this in more detail, I propose we shift the
> debate to the EnviroNet.
>
> I never proposed mixing the H2 and O2 to produce BANG. There are a
> number of ways of non-explosively combining the two gases safely, the
> simplest being a straightforward hydrogen flame.
>
> Brian
>
> Indrek Rebane wrote:
>
>>Hi Brian,
>>
>>Brian Ellis wrote:
>>
>>
>>>No way. Producing PURE H2 and PURE O2 to produce PURE water would be
>>>horrendously expensive, energy consuming and polluting.
>>
>>
>>Not so, pure water would be a by-product of discharging the fuel-cell.
>>(Ability to store solar energy for winter time anyone?)
>>
>>But by just mixing hydrogen and oxygen near fire:
>>2H2+O2 => 2H2O + BANG!
>>
>>Indrek
>>
>>--
>> Indrek Rebane | Borthwick-Pignon
>> Electronics Engineer | Tartu Science Park
>> Phone: (+372) 7 302 641 | Riia 185, 51014 Tartu
>> Fax: (+372) 7 383 041 | Estonia
>> [log in to unmask] | www.bps.co.ee
>>
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