The following comments are Co/ Dr Paul Olivier, cut from a
recent post to the "
Improved Biomass Cooking Stoves" discussion list (you may need to sign up to access original post... and its not archived at the time of posting).
..."
I just returned last week from Malaysia in order to look into the gasification of palm kernal shells. This looks quite feasible, even without forming these shells into pellets. But bottled gas in relatively rich Malaysia is very cheap compared to relatively poor Vietnam, because the Malaysian government subsidizes bottled gas. At the same time, Singapore and large parts of Malaysia were recently subjected to dangerous levels of smoke from the large-scale burning of biomass in Sumatra over a period of several weeks. The entire city of Singapore was virtually shut down for a few weeks. Once again, why bother with biomass stoves as long as governments are willing to subsidize the price of bottled gas? After all, no biomass stove can match the safety (low CO and low PM), convenience (the simple twist of a knob) and turn-down ratio (1 to 99) of bottled gas.
I design biomass stoves the way I do primarily because I believe something should be done about global warming and ocean acidification. Here in Vietnam huge quantities of rice hulls, rice straw, coffee husks, pine forest debris and many other types of biomass are uselessly burned, while many people, especially in urban areas, burn coal and bottled gas to cook their food. So ridiculous. At the same time large portions of the Mekong (the center of food production in Vietnam) will soon be under water as sea levels continue to rise at their current rate.
But replacing bottled gas is not my only goal. Burying biochar is also critical in combating global warming and ocean acidification. Here CO2 is pulled from the air and locked in the soil for hundreds of years. At the same time, there are the many benefits of biochar that I have read about from scientists such as Ogawa (AM fungi), Lehmann and Joseph (a member of this stove list). Also in Vietnam, Laos and Cambodia, we have done more than 22 biochar studies with biochar from my gasifiers. These studies show remarkable numbers with regard to plant and animal growth. Then finally, in the city where I live, rice hull biochar is a hot commodity when incorporated into potting soils in greenhouses. Why burn biochar when it sells at such a good price, especially when it is worth far more than the biomass from which it was derived? So I cannot help but conclude that stoves that do not burn biochar, but make it, are incredibly important. Also, if I were to burn biochar within the reactor of my TLUD, this would be such an inefficient exercise, since the distance between the pot and the burning biochar would be so great.
No, it makes so much sense to keep the biochar. We can feed biochar to pigs, cows and chickens. We then take the solid waste from these animals and feed it to BSF larvae. We then take the residue of the larvae and feed it to red worms, and finally we take the vermi-compost loaded with biochar back to the soil. The biochar passes through the gut of three creatures before it gets incorporated into the soil. When we put biochar in a dry bedding for pigs and cows, listen carefully, there is no urine or ammonia smell. We have virtually odorless pig pens. The pigs play in the bedding and even eat it. More than 60 farmers in the area have now adopted this way of raising pigs. All of these farmer use biochar. Also there are no flies around these pig pens. Antibiotics are no longer used. Not a single piglet gets diarrhea.
The pig farmers make rice wine, and the mash gets fed to the pigs. I will start supplying gasifiers to these pig farmers for the distillation of their rice wine. The burning of low-grade biomass for rice wine distillation will stop. The farmers will then be able to make their own biochar to incorporate into pig bedding..."
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