Dear Bjarne and stovers all, First, I must greet my colleague from a former Jatropha promotion program in Tanzania, Bjarne Laustsen, and congratulate him on the funding he has been awarded to finance pellet making equipment and stove manufacturing for his ‘jiko bomba’. Well done, and I wish you great success. Secondly, it’s time that all of us partisans in the debate over whole Jatropha seed vs. pelletized Jatropha-based fuel reminded ourselves that there is a god’s plenty of room in the improved cook stove biz for every successful innovation and a variety of fuels. “Let a 1000 stoves bloom” (apologies to Mao). No one doubts that in the right circumstances pelletizing or briquetting will produce excellent fuels that can be burned cleanly in appropriate stoves. I trust the partisans of pellets and briquettes will concede that naturally perfect fuels such as whole seeds are appropriate for stoves that can handle this complex fuel. As Richard Stanly, the premier promoter of briquetting, noted a recent posting. “Agreed, that there is no sense in briquetting or pelletizing any fuel that is already of uniform size and reasonable energy density.” However, there are good reasons why pelletizing Jatropha seed is probably not a good idea in many situations, as we will discuss below. Thirdly, let me clarify the stove performance issue that I raised concerning incomplete combustion in our ‘jiko safi’ stove that is fueled by whole unprocessed Jatropha seed. In response to an observation by Dean Still last week about the need of some minimal moisture in gasified fuels, I mentioned the single time that we used some old seed – probably over a year in storage – in jiko safi and got poor results. This never happens when we use reasonably fresh, and slightly moist, seeds. As Bjarne knows from independent field tests conducted during the Jatropha project we both worked on in recent years, jiko safi burns very clean with minimal emissions, and does not have a problem combusting the complex of different gases in whole Jatropha seed. Fourthly, let’s clarify the chronology of early Jatropha stove development before it gets lost in historical revision. Bjarne’s earlier stove ‘jiko mbono’ which I greatly and publicly supported in its early stages, including postings on this stove list, could not reliably combust the multiple gases of whole Jatropha seed. Paul Anderson correctly analyzed the problem of this stove as not getting the primary and secondary air supplies right. Out frustration with this failure came the effort of by Seattle stovers, notable Dr. Dave Covert and Dave Otto (my twin brother) that led to design and development of the jiko safi. They added a central air intake in the combustion chamber, and used an elongated stove pipe to deal with the air supply challenge and remove remaining emission from the breathing area of cooks and others nearby. Just as the first jiko safi was being tested, Bjarne gave up working on his stove fueled by whole seed, in part because he could not solve this design problem, and began to work with a less demanding pelletized fuel, for which he has developed an interesting new stove. Fifthly, let’s look at the economics of pelletizing fuel, in particular the pellets that go into Bjarne’s jiko bomba. As I remember, for Bjarne’s operation the set of three diesel-fueled motorized machines imported from China – an expeller to separate oil from presscake, a hammer mill to process rice hulls into usable bits, and a pelletizer (extruder?) to process the ingredients together – cost about US$10,000. The level of investment is fine if you have a donor handy as Bjarne did; but how financially sustainable, not to mention replicable, is such a system? A companion economic (and environmental) issue is the transport by truck of the pellets’ ingredients from whence they are generated, i.e., rice growing areas and many dispersed Jatropha growers, to a central location, over hundreds of kilometers for rice husks and J seeds; and then re-transport of this pelletized fuel back to energy consumers. This approach seems polar opposite from the principles of pelletizing or briquetting with materials found in the immediate surroundings and used by local households, as promoted by Legacy Foundation, for example. Sixthly (don’t fear, the end is not far), I do agree with Bjarne that there is a lot of Jatropha seed grown in Tanzania, and I would add, in at least 100 other tropical countries. And we agree that some farmers are beginning to recognize its commercial value. However, just because farmers are beginning to sell seed, that does not mean there will not be enough fuel seed to go around. Farmers respond readily to market opportunities, and thousands of Tanzanians have already greatly increased plantings of Jatropha – including over 25,000 rural households in that project Bjarne and I worked on from 2008- 2011, mainly growing Jatropha in hedges that protect fields. In fact, hedges of those 25,000 growers will soon start producing many tons of seed annually, and that project had promised these farmers both markets for seed and stoves that burn their seed just as it comes from the hedges. We all have far more to fear from the rapidly dwindling supply of unsustainably harvested woody biomass than from the highly unlikely possibility of using up all the available Jatropha seed! Finally to Bjarne’s statement that, “…most farmers will never burn a cash crop, they will sell it. He will rather sell it for cash he can spend and then ask his wife to collect firewood for fuel, than burn the seeds up in a stove”. To the degree that this accurately represents men farmers’ opinions, is it not time that we stopped taking such male perspectives as a given that cannot be changed, and start working to relieve women (and the environment) of the burdens of firewood as the main source of domestic energy in rural areas? On an experimental basis, we will soon start marketing jiko safi though Village Community Banking (VICOBA) associations – self-managed microcredit groups mainly of women – in Jatropha growing areas. Once women have stoves fueled by on-farm Jatropha seed as an option to the endless treks to the bush for ‘free’ firewood, it will be interesting to see who controls the use of the family’s Jatropha seed, and whether these households decide to plant more J hedges. Stay tuned. Perhaps the most positive way to view the relationship of these two Jatropha fueled cooking systems -- pelletized fuel in Bjarne's jiko bomba and whole unprocessed seed in jiko safi of Jet City StoveWorks -- is to suggest that the pelletized fuel and its stove will find a good market within a certain economically prescribed proximity to the pellet making operation, and the whole seed stove will initially be attractive mainly to cooks beyond the geographic reach of the pellet market. That said, this is not a meeting of colonial powers in Berlin in the 1880s and we are not dividing up Africa once more; so of course, some consumers in areas where pellets are marketed adn whole seeds are on sale will have a choice among these two stoves and others. That should be interesting. I remain grateful for Bjarne's groundbreaking efforts in Jatropha gasification, and very impressed by his tenacity and inventiveness. Sorry for such a long post, and thanks for those who read through it all. Jonathan
Date: Tue, 22 Jan 2013 11:23:14 +0300 From: [email protected] To: [email protected] Subject: Re: [Stoves] Jatropha fruit as fuel? Hey Jonathan The issue of incomplete combustion of Jatropha seeds in a TLUD gasifier stove has in my opinion very much to do with that you by heating up the seeds in the stove gets two different types of gasses. Pyrolysis gasses and vaporized Jatropha oil. The last ones is much more difficult to crack and burn, they will therefore require higher temperatures and more secondary air for full combustion. But it will also require much more control on the burning rates in the stove. That is one of the reasons why we have changed our initial Jiko Mbono gasifier cookstove to our new Jiko Bomba cookstove that use pellets as fuel. That brings me to another issue you bring up. Why make pellets when farmers just can burn their Jatropha seeds. I find that there are several good reasons for that. First, Jatropha seeds are in many part of Tanzania today a cash crop for farmers. They can sell the seeds at good prices to companies that press Jatropha seeds for getting Jatropha oil. So most farmers will never burn a cash crop, they will sell it. He will rather sell it for cash he can spend and then ask his wife to collect firewood for fuel, than burn the seeds up in a stove. Secondly, I agree with you that there are good quantities of Jatropha seeds, however these quantities are still relative small. It will only be few farmers that will be able to collect the 800 kg to 900 kg of Jatropha seeds that will be required for a household's yearly demand for fuel. This will then not leave anything for meeting other households needs for fuel. However there are big quantities of agricultural residues that are not utilized efficiently. These agricultural residues can be turned into efficient fuel if they are pelletised. Calculations shows that if 30% of available agricultural residues in Tanzania are turned into pellets and burned in efficient gasification stoves, they would be able to cover all Tanzania's households demand for fuel. Many of these agricultural residues requires a binder and lubricator for pelletizing. This is especially the case for rice husk. 10% to 20% of jatropha press cake mixed into agricultural residues works very good. Such smaller amount of Jatroha press cake and less amount of jatropha oil does not represent a problem for full combustion. Our Jiko Bomba cookstove and its pellets burns very clean and efficient when operated in the right way. Thirdly. Using These kind of pellets in our stove is very economical. Household that use our stove an pellets can save over 50% on there energy bill compared to when they use charcoal, at least here in Tanzania. Besides that by using pellets made form agricultural residues households will use only renewable energy sources. This will contribute to reducing the alarming deforestation rates here in Tanzania. You can find more information on our stove on this link: www.treetanz.com The site is in Kiswahili, but I believe you can read it. Bjarne Laustsen _______________________________________________ Stoves mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org for more Biomass Cooking Stoves, News and Information see our web site: http://www.bioenergylists.org/
_______________________________________________ Stoves mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org for more Biomass Cooking Stoves, News and Information see our web site: http://www.bioenergylists.org/
