[Stoves] Lignite in Mississippi

Crispin Pemberton-Pigott crispinpigott at gmail.com
Tue Sep 20 10:15:37 CDT 2011


Dear William

 

>When I first heard about the project I questioned the wisdom of using the
lignite found in our area of Mississippi (about 15 miles from the plant
location). I’ve never heard of anyone trying to burn this lignite. Even in a
forest fire the “outcroppings” of lignite don’t burn. 

 

What interested me was the claim that the emissions were low. These days
that statement has no value unless you see exactly what they are talking
about because there is so much rampant green-washing of any and everything.

 

The ‘low emissions’ are the usual scrubbing one would expect of lofted
particles and Sulphur which is a profitable thing to take out in any case.
No one in his right mind emits SO2 these days. S is worth too much.

 

I see now they are calculating the CO2/kW as their ‘reduced emissions’. That
claim is only valid while there is a price on the head of CO2.  I see from
the link you provided they have a buyer so I say, take the money and run, if
they are willing to pay for it.

The main issue, at its root, is the infernal idea that black and organic
carbon particles of incomplete combustion are ‘inherent in the fuel’. This
gripped the minds of industry and academia years ago when un-removable
things like Sulphur plagued the area around coal-fired power and industrial
plants. It was sold on the basis of SO2 causing ‘acid rain’ – something
shown to be completely untrue in the following years. Even the main guy
promoting the ‘danger’ has published on the subject, saying there never was
such a thing as an ‘acidified lake’ resulting from coal combustion. However
the idea stuck that there are ‘inherent emissions’ in the coal just waiting
to come out.

 

Then the logical leap was taken to include all emissions as if they are
inherent (i.e. inside the coal already). This led to lignite being targeted
as a ‘dirty smoky fuel’ when in fact what they had were power station
burners build for low volatiles coal burning inappropriate fuel (lignite)
generating lots of smoke and all of a sudden we had ‘proof’ that lignite
cannot be burned cleanly.

 

I have been talking to Jim Jetter about the poor measurement efficiency of
the Dustrak DRX we are using for determining PM 1.0 emissions by coal stoves
in Ulaanbaatar. The use of light as a detection method gets less efficient
as you get closer to the lower limit which is 0.1 microns. What I find most
important is that whatever the measurement efficiency, the fact that the air
going into the stove is much dirtier than the emissions coming out! So if
the measurement efficiency is 10%, and the air shows 300 µg/m3 perhaps the
real value is 10 times that (unlikely) or the machine self-corrects a
reading of 30 and prints out 300. We are not sure at the moment. 

 

The point is that lignite can be burned extremely cleanly if the combustor
is designed to suit it. 

 

Incidentally you mention of the exposed lignite nor burning can be
attributed to the weathering of the surface. Even underground it changes
significantly for about 2 metres of ‘edge’ which they call ‘burned’ I think.
It loses its volatiles and is more like carbon mixed with clay. If heated in
a fire it will probably burn but not on its own under an overhead fire.

 

Regards

Crispin

 

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