[Stoves] The rewards of densification

[Thomas Reed]

Dear All Densifers, Stovers and Gasifiers:

In 1973 I first became interested in methanol as a replacement for 
gasoline and biomass as the ultimate replacement of coal or natural gas.

In 1977 I moved from Concord, Ma. (which I loved) to Golden, CO  (also 
great) to work seriously on alternate energy at the then Solar Energy 
Research Institute (SERI, now NREL).  Initially we had no laboratory 
facilities of our own, and a big budget (Carter, not Reagan).  

Coal is old densified biomass and great fuel with significant downside.  
Biomass is 2/3 air and while it has 2/3 of the energy content of coal on 
a MASS BASIS, it has 1/10th the energy on a volume basis, making it MUCH 
more difficult to ship, store and use.  An auxilliary benefit of 
densification is that moisture content must be reduced below 15% for 
densification, so we don't have to ship a lot or water. 

I concluded that if biomass is to be a competitive fuel it should be 
densified for many applications. 
------------------------------------------------------------------------

In 1977 I attended a conference in Canada that alerted me to the 
possibility of DENSIFYING biomass. from ~ 0.3 g/cm3 to > 1 g/cm3, 
removing much of this difference.  I wrote an article (with Becky 
Bryant) available at WoodGas.com on

/*DENSIFIED BIOMASS: A NEW FORM OF SOLID FUEL:*/ Tom Reed and Becky 
Bryant, A "State of the Art evaluation of densified biomass fuels" with 
documentation of processes, energy balance, economics and applications. 
First published in 1978, & still the best (only?) text on theory and 
practice. Second edition with Paper on Energy of Biomass Densification 
appended.  
ISBN 
1-890607-16-9                                                           
35pp         $22.50

We also commissioned  Coors here in Golden to do some tests on 
densification at higher temperatures, the very scientific Appendix to 
this 2nd edition.  It shows that if the sawdust is heated to 250 C the 
energy content rises from 19.3 kJ/g to 23 kJ/g (8290 to 9890 Btu/lb), 
significantly closer to coal, and that the "specific work of 
densification" drops from 10 J/g to <3 J/g.  Unfortunately, heating 
biomass to 250 C (torrefaction) also produces blue haze, so must be done 
fast and enclosed. 

This should be a challenge to all of you to develop densification at 
various levels for biomass use. 

I hope Tom Miles can post this in his section on densification. 

Onward to a biomass future someday (sooner rather than later)

TOM REED     BEF




Tom Miles wrote:
> Per,
>
> We can put your paper on the stoves website along with the pictures from
> Alexis and the earlier link to the briquetting by Battacharya
> http://www.bioenergylists.org/en/retasiabriquette
>
> Tom
>
>
> -----Original Message-----
> From: stoves-bounces at listserv.repp.org
> [mailto:stoves-bounces at listserv.repp.org] On Behalf Of Per-Einar Rosenhave
> Sent: Friday, May 09, 2008 11:17 PM
> To: stoves at listserv.repp.org
> Subject: [Stoves] Screw-press briquetting machines
>
> Hello George and all,
>
> I also immediately looked for more details when I saw the posting from
> Alexis. The same goes for other postings with great ideas or solutions. A
> small drawing or reference to one is always very welcomed since it "says
> more than a 1000 words" - you know. But it does not seem to me this forum is
> so concerned about the practical aspect of things. (I ask forgiveness if my
> assumption is wrong.) Well, - anyway George, I have a paper on Screw-press
> briquetting machines and briquette-fired stoves based on the Renewable
> Energy Technologies in Asia Programme which provides the needed details. I
> can post it to you if interested..(Don't know if I can attach it here.)
>
>  
>
>  
>
> With kind regards
>
> Per-Einar Rosenhave,
>
> Associate Professor Vestfold University College,
>
> Industrial Environmental Technologies,
>
> Faculty of Maritime Education
>
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