Re: GAS-L: Re: LPG and steam reforming

[AJH <andrew.heggie@dtn.ntl.com>]

On Thu, 21 Nov 2002 15:00:28 +1100, "Jim Bland"
<enecon@ozemail.com.au> wrote:

>Propane (C3H8) and butane (C4H10) are extracted from oil and natural gas
>production.

Good post Jim.

In uk lpg is being encouraged as a green fuel. Partly I believe
because high pressure pumping operations have meant it is in surplus.

Tom Reed made the point that gas pipelines are expensive, I believe
they are quite efficient at transporting energy. The point in favour
of a methane economy is that it and its infrastructure exist in the
western world. Any competitive technology would have to compete with a
grid with largely amortised costs.

>  LPG is a mixture of propane and butane, anywhere from 100%
>propane to 100% butane.  The mix depends on the end use and the ambient
>conditions.  In southern Australia, for automotive use, you will find that
>LPG contains more propane in winter to keep the vapour pressure high for
>easy starting, and less propane in summer.

Southern Europe seems to have lpg with this higher butane content, it
enables better mileage. Incidentally I run an lpg powered vehicle, it
only achieves 75% the mileage compared with petrol. It has advantages
of cleanliness which should increase engine life.

<snip primer on refining and reforming>

>All of the above processes run at high temperature (up to 1000°C - 1800°F)
>and pressure (150 bar - 2250 psig), require a massive scale to be
>competitive, and are totally unsuited to the scale of biomass gasification
>that this list discusses.  A world-scale methanol plant is currently at
>least 2000 t/d, and costs about US$250 million.  If this were made from
>green wood at 60% efficiency, you'd need about 3500 t/day of wood.  I expect
>you could harvest this from a sustainably-managed forest of about 600 square
>km (240 sq miles).

I haven't checked your figures but wonder at your 60% efficiency.
Whilst I have no doubt you are right in principle I thought these
plants worked at quite high thermal efficiencies. I remember reading
of one in Holland producing MBTE (I think as an octane enhancer) from
coal which co produced 2MW of electricity for sale.

In fact your 3500tonne/day wood plant is not beyond the realms of
possibility as it is the same order of magnitude of a wood pulp plant.
The crux is that there do not seem to be any current harvesting
systems which can deliver biomass at a price which will compete with a
fossil fuel feedstock.

Whether this will be the case in the future is another matter, I can
imagine a hybrid PV solar and biomass thermal plant might have a good
"fit" for co producing a transport fuel, taking into account the "non
scheduled" delivery of PV and the similarly seasonal production of
biomass.

AJH

Gasification List Moderator:
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Energy Foundation, www.woodgas.com
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