[Stoves] pellets in an urban setting

Mon Jul 29 12:24:47 CDT 2013

Paul and cc list (but the questions below pertinent to any and all) 

This is to hope that you can perform a few more experiments re fuels. I am sure all your comments are correct comparing loose husks to pellets, but wonder if you could try and report on several other fuel options as well - especially telling us about prices in Vietnam. Your comment about running stoves for free because char produced in your stove is worth more than the pellets going in is very important. Can you give more cost (per kilo) detail on that? The next three (are there more?) items are extensions - both on technical results and on economics. 

First is wood chips. The stove camp activity was all based on this product because of a request from a South American (?) company wanting to harvest a large older forest, I think specifically planted decades ago to save nearby old growth forests. I presume chips are being preferred over pellets for cost reasons (I have heard a 3:1 price difference). Hopefully you can find a chip supply and tell us on their performance and economics in any of your stoves as well. 

Second is any fuel made by hand from paper, leaves, grasses, rice husks (?), etc - as promoted by Richard Stanley, etal. Presumably you saw my recent report on making something specifically for TLUDs. The advantages here are making productive use of materials having no other possible use and supplying jobs for low-income people. I am about also to respond to recent message from Richard along these lines (re using only hand muscles). 

Third is use of small twigs, ag residues, straws, reeds, grasses, etc (similar to rice husks, but denser and available where husks are not) that can be used without any processing.. Again, maybe a job creator - with hope that the char value exceeds the fuel cost This presently is the fuel of choice for backpackers as it can be found everywhere. Can this approach be expanded, again as a way for fuel preparers and cooks to make money rather than only expend it? 

Fourth (and last) is the supply of larger wood (maybe only branches?) cut into small pieces (I saw a lot from board lumber cut to about 6-12 inch length almost all less than 1 square inch cross-section (NOT the standard fuel in the field). This was the main fuel alternative to chips at the stove camp for those not using TLUDs. Presumably this is also possible in Vietnam for vertical stacking in your device with optimum heights and packing densities. Again emphasis to be on economics - still hoping to find lower fuel costs than pellets, but less bulky than husks, if possible. 

I pick on you as probably having some local labor available to try these alternatives with a chance of selling more stoves where costs can be an important factor - and you knowing of the importance of either getting more char in the ground or of making char with use of the pyrolysis gases. I'll be glad to split the costs of trying these other quite-different fuel options in your stove. 

Somewhat along these lines, this is also to alert all to an EPA-GACC webinar on 20 August on batch stoves (10:00 AM Eastern). This received a few days ago: 
The online registration form ( https://unfoundation.conferencinghub.com/attendee/RegisterLogin.aspx?hubconfID=1632144&qtID=1&act=reg&cp=2861 ) includes a place to enter comments or questions you would like addressed during the webinar. 

So Paul, thanks in advance for anything new you can report on the economics of these six fuel options. 

Ron 

----- Original Message -----
From: "Paul Olivier" <paul.olivier at esrla.com> 
To: "Discussion of biomass cooking stoves" <stoves at lists.bioenergylists.org> 
Sent: Sunday, July 28, 2013 9:06:32 PM 
Subject: [Stoves] pellets in an urban setting 

I am getting excited about the use of pellets. In an urban setting in a developing country such as Vietnam, a pellet gasifier should be a lot more socially acceptable than a loose biomass gasifier. 

Since pellets can be as much as 8 to 10 times more dense than loose biomass, the reactor can be much smaller. A net reactor height of only 8 inches is all that is needed to give a burn time of up to 90 minutes. Since the unit is small, it is lightweight. The reactor weight is but 1.2 kg. It is easy to handle. With such a small reactor, the manufacturing cost drops considerably. This means that the most heat-resistant and non-corrosive stainless steels become affordable. This adds years to the life of the unit. This also means that the unit looks good and takes on the appearance of a high-end kitchen utensil. If the unit does not look good, it will be hard to sell. 

https://dl.dropboxusercontent.com/u/22013094/150%20Gasifier/Short/Photos/IMG_1571.JPG 

Pellets can be more cheaply transported into urban areas than loose biomass. Dealing with loose biomass can often be dusty and messy. The storage of pellets in a kitchen takes up much less space than the storage of loose biomass. With pellets there should be a lot less emissions of particulates. 

Biochar pellets are easier to quantify than loose biochar. A measurement of biochar volume is all that is needed. There is only a small reduction in volume as when a pellet is transformed into biochar. 

The flame put out by a pellet gasifier is rich and intense throughout the burn: 
http://www.youtube.com/watch?v=84qDsbBO9p8 

The flame does not turn ethereal. 

It is true that pellets cost more than loose biomass. But pellets are cheaper to transport into a city than loose biomass, and the biochar produced from pellets has a higher value in Vietnam than the original pellets. I foresee the possibility of an exchange program where pellets are supplied free-of-charge in exchange for the biochar produced from these pellets. 

Thanks. 
Paul Olivier 

-- 
Paul A. Olivier PhD 
26/5 Phu Dong Thien Vuong 
Dalat 
Vietnam 

Louisiana telephone: 1-337-447-4124 (rings Vietnam) 
Mobile: 090-694-1573 (in Vietnam) 
Skype address: Xpolivier 
http://www.esrla.com/ 
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