Newsgroups: sci.energy
From: John De Armond
Subject: Re: Electricity from Wood (WSJ 12-2-93)
Message-ID: <+kq2#!m@dixie.com>
Date: Wed, 08 Dec 93 17:39:51 GMT

dietz@cs.rochester.edu (Paul Dietz) writes:

>No, I believe it said that biomass already surpasses wind and solar
>combined.  There is a great deal of capacity already installed (at
>pulp mills, for example).  This capacity could be expanded by
>installation of more efficient gasifiers/turbines.  Pulp industry
>wastes alone could supply about 4% of the current US demand for
>electricity.

I just 1 week ago last Sunday finished a project automating the power house
of a large pulp mill.  Whomever is making the 4% claim is wildly
exaggerating.  This mill, one of the largest kraft mills in the US,
burns every bit of wood scrap they can get their hands on.  There are
two different rail spurs, each feeding a car upender.  There are 6
semi truck tippers (devices that pick up the semi truck and dump its
contents).  And there is a barge facility.  There are 6 multi-fueled
power boilers and 2 recovery boilers that burn the waste stream from the
mill.  Given all these sources, the plant still only generates about half its
electrical needs.  And then they have to run at least 2 of the power boilers
on purchased fuel (gas, oil or coal) all the time.  The plant consumes an
average of 90 MW and the turbine plant generates up to about 45 MW.
About 20% of the steam generated is used to make power, the remainder
being used for process steam.  The turbines are non-condensing and serve
as pressure reducing stations, feeding their discharges into 65 and 35
psi steam headers.  The boilers are equipped with "condensing stacks",
that is, the flue gas is cooled all the way down to ambient temperature
in order to recover valuable chemicals in the flue condensate.  This
configuration is more or less the same as I have seen in other similarly
sized mills.

One of the major features of the control system we designed is real
time, on-line fuel costing that determines which boiler burns what fuel
in order to minimize cost.  I submit that no amount of gassification/
gas turbine fiddling could significantly change the energy balance
at this plant.  Essentially all the heat generated in the boilerhouse
is used either to generate electricity or as process heat.  I really
have to wonder if whomever it is that makes these wild 4% claims has
even ever visited a modern paper mill.  I suspect not.

John

Newsgroups: sci.energy
From: John De Armond
Subject: Re: Electricity from Wood (WSJ 12-2-93)
Message-ID: <96r230n@dixie.com>
Date: Fri, 10 Dec 93 06:18:39 GMT

dietz@cs.rochester.edu (Paul Dietz) writes:

>In article <+kq2#!m@dixie.com> jgd@dixie.com (John De Armond) writes:

>> I really
>> have to wonder if whomever it is that makes these wild 4% claims has
>> even ever visited a modern paper mill.  I suspect not.

>Well, here's the paper, so you can judge for yourself:

>  E. D. Larson "Biomass-Gasifier/Gas Turbine Cogeneration in the
>   Pulp and Paper Industry", Trans. of the ASME, J. of Eng. for Gas
>   Turbines and Power, October 1992, pages 665-675.

>From the abstract:

>  "At an energy-efficient kraft pulp mill, a BIG/GT cogeneration
>   system could produce over three times as much electricity and
>   as is typically produced today.  The mill's on-sit energy
>   needs could be met and a large surplus of electricity would be
>   available for export.  Using in addition currently unutilized
>   forest residues for fuel, electricity production would be nearly
>   five times today's level."

Does the abstract say what E.D. Larson does?  Frankly this reads like
the academic masturbation one finds in grant applications and
"NASA Tech Briefs".

>Now, I could well believe that the "conventional" system against which
>they are comparing is a straw man.  Perhaps you could give us some
>more information about the place you visited, for comparison (electricity
>(kWh) and steam (GJ) needed to make a to make a tonne of air-dried
>pulp and the efficiency of the boilers and steam turbines would be
>interesting.)

I don't know what the cost per ton is and if I did I'd be reluctant
to quote numbers without the company's position.  I'd imagine that
to be a business-confidential number.  It doesn't really matter
for the purposes of evaluating this claim since we're dealing with
orders of magnitude.

Turbine efficiency doesn't matter much, since they serve as reducing
stations with almost no steam ending up in the condenser.

I don't know the actual numbers on the boilers because they do not
compute heatrate.  I am impressed with the heat recovery systems
present.  The wet flue discharges flue gas in the range of 140 to 160
degrees F depending on the weather.  Residual heat is recovered from
the srubber and is used for process hot water.

Consider the numbers.  This mill uses somewhere in the range of 90 MW.
Under ideal conditions, the turbines can make half that by diverting
20-30% of the total steam mass to the turbines.  That means by far
the bulk of the plant's energy is supplied as steam made by burning
stuff.  Suppose the plant could wave a magic wand and cut the process
steam requirement by a third.  That would mean the power house could
burn exclusively wood waste and could discontinue routine burning
of bought fuel (gas, coal, oil).  The plant would still burn all
the wood waste it could get.  Or consider if the plant were to
double its power production.  That would make the plant just about
self-sufficient.

I just don't see any room for increased power production to the point
where power could be exported.  It is still more efficient to supply
process heat directly with steam rather than first turning it into
electricity.  That pretty much limits what gassification/gas turbines
can do.

The practical aspect is it is very unlikely any new mills will be built,
super-efficient or otherwise, as long as the environmental war against
the pulp industry continues.  At least that is the consensus of the
staffs at this mill and at Bowaters.  The modern paradigm is debark
and chip the trees near the harvest point using portable plants and
transport the chips to foreign mills.  Plus the unscientific
conventional wisdom beer talk amongst the plant staff is the mill
barely breaks even and the company makes its money on the byproducts
derived from the waste stream.  I tend to believe something close
to this just by looking at the relative investments in the mill
vs the byproducts plant.

John

Newsgroups: sci.energy
From: ems@michael.apple.com (E. Michael Smith)
Subject: Re: Electricity from Wood (WSJ 12-2-93)
Message-ID: <1993Dec11.084353.4748@michael.apple.com>
Date: Sat, 11 Dec 1993 08:43:53 GMT

In article <bzs2nyj@dixie.com> jgd@dixie.com (John De Armond) writes:
>af017@Freenet.carleton.ca (David R. Smith) writes:
>
>>Incidentally, as far as wood energy conversion, it is very
>>simple chemically and industrially to convert wood chips into
>>ethanol.  In fact any pulp mill could be modified only slightly
>>to allow this production.
>>David Smith
>
>Oh boy, this ought to be good.  OK, Dave, tell us how it can be done.
>First, of course, accurately describe a paper mill of your choice
>complete with sizes and capacities just to show us you even have the
>general concept down pat.  And then tell us what you'd take out and
>add in to the process to make ethanol using the bulk of the same
>facilities.  Be sure to keep it easy and simple.  Remember now, the
>mods have to be "slight".

I'll help David a bit here (fellow Smith and all ;-).

At the point where you have wood chips, you add a LARGE
fermentation tank with Tricodermata Viridae to make sugar.
(multiple thousands of tons/day would be nice...)

Then another LARGE fermentation tank to make ethanol from the sugar.

Use all that steam you were talking about to keep things warm...

Send the fermented mash to a steam driven vacuum still...

(I don't know what all one would do with the rest of the paper mill,
though ...make paper I suppose.)  I think Dave was suggesting that
the mill could be modified to ADD alcohol production, not convert
away from paper to ONLY alcohol...

Alternatively, I suppose you could use a large vat for hot acid
hydrolysis of the wood chips ... but that would not be as
politically correct as the fermentation route...

Per size:  Geeze, that depends on the mill...  The one I'm most
familiar with is, well, gigantic.  Sits on the coast up near
Humbolt.  Larger than the old FORD plant was, I think...

I can see where you could use the pulp making equipment, and the
power/steam facilities.  Everthing after the pulp stage, though,
seems wasted to me...

--

E. Michael Smith  ems@apple.COM

'Whatever you can do, or dream you can, begin it.  Boldness has
 genius, power and magic in it.'  -  Goethe

I am not responsible nor is anyone else.  Everything is disclaimed.

Newsgroups: sci.energy
From: ems@michael.apple.com (E. Michael Smith)
Subject: Re: Electricity from Wood (WSJ 12-2-93)
Message-ID: <1993Dec14.004904.19283@michael.apple.com>
Date: Tue, 14 Dec 1993 00:49:04 GMT

In article <!#v2mg+@dixie.com> jgd@dixie.com (John De Armond) writes:
>ems@michael.apple.com (E. Michael Smith) writes:
>
>>>af017@Freenet.carleton.ca (David R. Smith) writes:
>>>
>>>>Incidentally, as far as wood energy conversion, it is very
>>>>simple chemically and industrially to convert wood chips into
>>>>ethanol.  In fact any pulp mill could be modified only slightly
>>>>to allow this production.

>>I'll help David a bit here (fellow Smith and all ;-).

>>At the point where you have wood chips, you add a LARGE
>>fermentation tank with Tricodermata Viridae to make sugar.
>>(multiple thousands of tons/day would be nice...)
>
>Ah but Mike, that's not simple and it can't be done with "minor modifications"
>to the existing plant.  "Minor modifications", to me is shuffling a
>pipe here, adding a pump there but basically using the existing equipment.

Well, I tried my best ...  But honestly, I can't think of much other
than the chipper and power plant that you would re-use.  And since
the wood often comes in chipped now, I'm not sure how you would reuse
the rest of the plant ...   No, WAIT!  I'VE GOT IT!  You can reuse
the billing and accounting departments and the head office too! ;-)

I DO hope that David was suggesting that you could ADD ethanol
production to a pulp plant easily, rather than a conversion, since
the whole paper making set-up is kind of useless for ethanol production.
(you don't need to roll up alcohol...) IF you ship by rail, you
might be able to re-use the rail spur, but all the shipping dock
would even need to be redone.  Better yet would be to add a tank
farm and use a pipe based shipping paradigm...  Actually, thinking
about it, and oil refinery would be easier to convert than a paper
mill...

Drat, I seem to be doing a better job of making your case than his ...
Oh well ;-)

--

E. Michael Smith  ems@apple.COM

'Whatever you can do, or dream you can, begin it.  Boldness has
 genius, power and magic in it.'  -  Goethe

I am not responsible nor is anyone else.  Everything is disclaimed.