Difference between revisions of "Micro Gasifiers"

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= Overview =
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= Overview<br/> =
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal"><font size="2">T</font>he so-called "micro-gasifier"</span></span></span></font></font></font></font> [[File:Differente stoves.jpg|right|300px|Rocket stove, Sawdust-microgasifier, TLUD-microgasifier (from left to right)|alt=Rocket stove, Sawdust-microgasifier, TLUD-microgasifier (from left to right)]] <font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">stoves convert dry biomass to wood gas and charcoal before the gas is burned. This gasification process needs heat and the absence of oxygen. The flame which offers sufficient heat for cooking is fed by the ascending wood gas and oxygen. This simple principle is used in a variety of contexts with different aims which mostly reflect local conditions.</span></span></span></font><span style="font-style: normal"><span style="font-weight: normal">The aim was to discuss the impact of changes in the stove-design on the performance of the stove with special focus on type of substrate in use, efficiency, emissions, handling and other unexpectable side effects.</span></span><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">The presentation included different models of microgasifiers and substrates which were presented by the participants in the room.</span></span></span></font></font></font></font><br/>
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<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal"><font size="2">T</font>he so-called "micro-gasifier"</span></span></span></font></font></font></font> [[File:Differente stoves.jpg|thumb|right|300px|Stove Types: Rocket stove, Sawdust-microgasifier, TLUD-microgasifier (from left to right)|alt=Rocket stove, Sawdust-microgasifier, TLUD-microgasifier (from left to right)]] <font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">stoves convert dry biomass to wood gas and charcoal before the gas is burned. This gasification process needs heat and the absence of oxygen. The flame which offers sufficient heat for cooking is fed by the ascending wood gas and oxygen. This simple principle is used in a variety of contexts with different aims which mostly reflect local conditions.</span></span></span></font><span style="font-style: normal"><span style="font-weight: normal">The aim was to discuss the impact of changes in the stove-design on the performance of the stove with special focus on type of substrate in use, efficiency, emissions, handling and other unexpectable side effects.</span></span><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">The presentation included different models of microgasifiers and substrates which were presented by the participants in the room.</span></span></span></font></font></font></font><br/><br/><br/><br/><br/>
  
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= History of Micro-gasification =
 
 
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= Micro-gasifiers - Short Story about the History of Micro-gasification<br/> =
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<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">As</span></span></span></font><font color="#00000a"><span lang="en-US"><span style="font-style: normal">'''descendants of the steam-engines'''</span></span></font><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">, microgasifiers went through different stages with changing names, models and usage. Gasifiers of smaller size and weight conquered individuals lives through</span></span></span></font><font color="#00000a"><span lang="en-US"><span style="font-style: normal">'''mobility, cooking and agriculture'''</span></span></font><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">. Woodgas drove millions of vehicles equipped with Imbert-generators during the 1930s and 40s in Europe. After propagation trough international cooperation since the 80s many households in Africa nowadays use microgasifiers as efficient cooking-stoves. Charcoal is a product of pyrolysis and stabilizes a highly fertile soil called Terra preta – an anthropogenic product rediscovered and reconstructed in recent years. Terra preta combines by-products of micro-gasifiers with recycling processes which form the basis of an ecological and social sustainable economy.</span></span></span></font></font></font></font><br/>
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">As</span></span></span></font><font color="#00000a"><span lang="en-US"><span style="font-style: normal">'''descendants of the steam-engines'''</span></span></font><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">, microgasifiers went through different stages with changing names, models and usage. Gasifiers of smaller size and weight conquered individuals lives trough</span></span></span></font><font color="#00000a"><span lang="en-US"><span style="font-style: normal">'''mobility, cooking and agriculture'''</span></span></font><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">. Woodgas drove millions of vehicles equipped with Imbert-generators during the 1930s and 40s in Europe. After propagation trough international cooperation since the 80s many households in Africa nowadays use microgasifiers as efficient cooking-stoves. Charcoal is a product of pyrolysis and stabilizes a highly fertile soil called Terra preta – an anthropogenic product rediscovered and reconstructed in recent years. Terra preta combines by-products of micro-gasifiers with recycling processes which form the basis of an ecological and social sustainable economy.</span></span></span></font></font></font></font>
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= Process and Products<br/> =
  
= Process and Products ([[:File:Micro_Gasifiers_Ariane_Krause_präsentation.pdf|Presentation]])<br/> =
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[[:File:Micro Gasifiers Ariane Krause präsentation.pdf|Presentation: Micro Gasifiers Ariane Krause presentation]]<br/>► [[:File:1 Session note - microgasifier.pdf|Micro Gasifiers]]<br/><u><font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">The '''challenge''':</font></font></font></u><br/>
  
<u><font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">The '''challenge''':</font></font></font></u><br/>
 
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Elimination of unacceptable emissions of CO and particles and pre-dominant use of firewood;</span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Elimination of unacceptable emissions of CO and particles and pre-dominant use of firewood;</span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Realize low-cost and user-friendly cookstoves to provide household-energy;</span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Realize low-cost and user-friendly cookstoves to provide household-energy;</span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Use wood and other dry biomass materials efficiently: with micro-gasifiers biomass is used with little emissions only to produce heat but at the same time also some charcoal is produced in little amounts.</span></font></font></font></font><br/>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Use wood and other dry biomass materials efficiently: with micro-gasifiers biomass is used with little emissions only to produce heat but at the same time also some charcoal is produced in little amounts.</span></font></font></font></font><br/>
  
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<br/><u><font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Technical and '''chemical processes''':</font></font></font></u>
  
<u><font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Technical and '''chemical processes''':</font></font></font></u>
 
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Differences of ''<span style="font-weight: normal">woodgas</span>'' as a product of a heat-related process and the use of dry biomass and ''biogas'' as a product from biochemical digestion of wet biomass were explained.</font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Differences of ''<span style="font-weight: normal">woodgas</span>'' as a product of a heat-related process and the use of dry biomass and ''biogas'' as a product from biochemical digestion of wet biomass were explained.</font></font></font>
 
*<font color="#00000a">“<font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">''<span style="font-weight: normal">Gasifiers” are devices in which the dry biomass is transformed into combustible gases on processes distinctly and controllably separate in time and location from the eventual combustion of the gases.</span>''</font></font></font>
 
*<font color="#00000a">“<font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">''<span style="font-weight: normal">Gasifiers” are devices in which the dry biomass is transformed into combustible gases on processes distinctly and controllably separate in time and location from the eventual combustion of the gases.</span>''</font></font></font>
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*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><span style="font-style: normal"><span style="font-weight: normal">There are two zones: (1) gasification of fire wood where pyrolysis happens (</span></span>''<span style="font-weight: normal">Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen)</span>''<span style="font-style: normal"><span style="font-weight: normal">and (2) combustion of woodgas; there are primary and secondary airflow respectively. As for the gasificiation a little amount of oxygen is needed and for the combustion sufficient oxygen needs to be on spot, the secondary airflow is bigger than the primary airflow.</span></span></font></font></font><br/>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><span style="font-style: normal"><span style="font-weight: normal">There are two zones: (1) gasification of fire wood where pyrolysis happens (</span></span>''<span style="font-weight: normal">Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen)</span>''<span style="font-style: normal"><span style="font-weight: normal">and (2) combustion of woodgas; there are primary and secondary airflow respectively. As for the gasificiation a little amount of oxygen is needed and for the combustion sufficient oxygen needs to be on spot, the secondary airflow is bigger than the primary airflow.</span></span></font></font></font><br/>
  
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<br/><u><font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">'''Characteristics of the products:'''</font></font></font></u><br/>
  
<u><font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">'''Characteristics of the products:'''</font></font></font></u><br/>
 
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Emissions of '''Carbon Monoxide (CO)''' and '''Particulate Matter (PM)''' from micro-gasifiers are comparatively low to other cookingstoves</font></font></font><br/>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Emissions of '''Carbon Monoxide (CO)''' and '''Particulate Matter (PM)''' from micro-gasifiers are comparatively low to other cookingstoves</font></font></font><br/>
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">With micro-gasification also a valuable by-product is produced: approx. 10% of the carbon that was contained in the biomass will be thermally stabilized and bounded in little amounts of charcoal that remain in the stove. There are stove-designs that also use the charcoal produced for thermal purposes and thus burn it. Another approach would be to use the charcoal as so-called “biochar” which means to add the charcoal to compost pits or directly to the soil to improve soil quality after the principles of “Terra Preta”</span></font></font></font></font>
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*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">With micro-gasification also a valuable by-product is produced: approx. 10% of the carbon that was contained in the biomass will be thermally stabilized and bounded in little amounts of charcoal that remain in the stove. There are stove-designs that also use the charcoal produced for thermal purposes and thus burn it. Another approach would be to use the charcoal as so-called “[[Biochar|biochar]]” which means to add the charcoal to compost pits or directly to the soil to improve soil quality after the principles of “Terra Preta”</span></font></font></font></font>
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== General Information<span style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif" class="Apple-style-span"></span><br/> ==
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== General Information<br/> ==
  
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">How large can you build the model with that simple structure?</font></font></font><br/>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">How large can you build the model with that simple structure?</font></font></font><br/>
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**<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- No scientific answer is known to the speakers, but the largest personally observed one is in operation at ATB,''Leibniz Institute of Agricultural Engineering in Potsdam-Barnim ''<span style="font-style: normal">and </span>has the size of an oil barrel. The model works well. The advantage of micro-gasifiers is that they are easy to build only with resources that are available on spot to be used for constructing. So the size may depend on the available materials also.</font></font></font>
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**<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- There is also thermo-chemical process named “gasification” which is realized mostly in swirling beds and ment for larger scale implementations. Experiments at TU Berlin are done e.g. at the chair for ''Energy Process Engineering and Conversion Technologies for Renewable Energies'' (FG EVUR). But here we focus on decentralized and small-scale realization of gasificiation in micro-gasifiers.</font></font></font>
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**<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- There is also a minimum size as well so that the volume of substrate should be at least 300 ml. Otherwise heat losses at the stove's surface are too big compared to the produced heat inside and the stove will not run properly.</font></font></font>
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- No scientific answer is known to the speakers, but the largest personally observed one is in operation at ATB,''Leibniz Institute of Agricultural Engineering in Potsdam-Barnim ''<span style="font-style: normal">and </span>has the size of an oil barrel. The model works well. The advantage of micro-gasifiers is that they are easy to build only with resources that are available on spot to be used for constructing. So the size may depend on the available materials also.</font></font></font><br/>
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<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- There is also thermo-chemical process named “gasification” which is realized mostly in swirling beds and ment for larger scale implementations. Experiments at TU Berlin are done e.g. at the chair for ''Energy Process Engineering and Conversion Technologies for Renewable Energies'' (FG EVUR). But here we focus on decentralized and small-scale realization of gasificiation in micro-gasifiers.</font></font></font>
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*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font size="2">W</font>hat are health implications?</font></font></font><br/>
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**<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- There are certain improvements in the new design: the CO level falls extremely, also for the PM (clean emissions, few smoke)</font></font></font>
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- There is also a minimum size as well so that the volume of substrate should be at least 300 ml. Otherwise heat losses at the stove's surface are too big compared to the produced heat inside and the stove will not run properly.</font></font></font>
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*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font size="2">W</font>hat are health implications?</font></font></font><br/>
 
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- There are certain improvements in the new design: the CO level falls extremely, also for the PM (clean emissions, few smoke)</font></font></font>
 
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">How can we prevent the users from inhaling carbon monoxide?</font></font></font><br/>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">How can we prevent the users from inhaling carbon monoxide?</font></font></font><br/>
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**<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Design: Make</font></font></font><span class="Apple-style-span" style="font-size: 15px;  color: rgb(0, 0, 10);  font-family: Arial, sans-serif">sure to have sufficient secondary air</span><br/>
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<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Design: Make</font></font></font><span style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif" class="Apple-style-span">sure to have sufficient secondary air</span><br/>
 
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Have you compared the effectiveness and efficiency of biogas, wood gas and LPG?</font></font></font><br/>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Have you compared the effectiveness and efficiency of biogas, wood gas and LPG?</font></font></font><br/>
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**<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- We personally not yet. But there is research done to compare the efficiency of biogas, wood gas and maybe also LPG. For example the ''Centre for Research in Energy and Energy Conservation'' (CREEC) at the College of Engineering, Design, Art and Technology (CEDAT) at Makerere University, Kampala, is working on that. It is also our plan to set up a closer cooperation between TU Berlin (esp. Postgraduate program “Microenergy Systems”) in CREEC to continue to work on this in the future.</font></font></font>
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**<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- We started with water boiling tests to compare the demand of resource needed with a particular cooking method to boil a certain amount of water (and thus offer a specific amount of thermal energy to use) to see how much wood we would have used with open fire in comparison with the improved cooking method. We also want to compare this to “rocket stoves” which uses charcoal. But then we also have to account the process of making charcoal from wood first. There will be a more information about this in another presentation later.</font></font></font>
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- We personally not yet. But there is research done to compare the efficiency of biogas, wood gas and maybe also LPG. For example the ''Centre for Research in Energy and Energy Conservation'' (CREEC) at the College of Engineering, Design, Art and Technology (CEDAT) at Makerere University, Kampala, is working on that. It is also our plan to set up a closer cooperation between TU Berlin (esp. Postgraduate program “Microenergy Systems”) in CREEC to continue to work on this in the future.</font></font></font>
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<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- We started with water boiling tests to compare the demand of resource needed with a particular cooking method to boil a certain amount of water (and thus offer a specific amount of thermal energy to use) to see how much wood we would have used with open fire in comparison with the improved cooking method. We also want to compare this to “rocket stoves” which uses charcoal. But then we also have to account the process of making charcoal from wood first. There will be a more information about this in another presentation later.</font></font></font>
 
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">How old is the TLUD system?</font></font></font><br/>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">How old is the TLUD system?</font></font></font><br/>
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**<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- It was first invented in the 1980s, but the first commercial use started in 2000 (so it is a quite new technology)</font></font></font>
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<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- It was first invented in the 1980s, but the first commercial use started in 2000 (so it is a quite new technology)</font></font></font>
 
 
*Could the design be improved by using a fan?
 
*Could the design be improved by using a fan?
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**<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- There are two designs possible concerning the air flow: a forced air flow using fans or natural air flow only using the differences in temperature and thus in density of the air. Today we only show self-made lowtech designs with natural air flow. We decided for this because we wanted to be independent from electricity. You could easily use nearly empty batteries to operate a fan to have an improved forced airflow, but the problems come when the batteries are empty and there is no place to dispose or recycle them safely. We also plan to work on the design of lowtech bellows to make the natural draft micro-gasifier more convenient in use, esp. at the starting time.</font></font></font>
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- There are two designs possible concerning the air flow: a forced air flow using fans or natural air flow only using the differences in temperature and thus in density of the air. Today we only show self-made lowtech designs with natural air flow. We decided for this because we wanted to be independent from electricity. You could easily use nearly empty batteries to operate a fan to have an improved forced airflow, but the problems come when the batteries are empty and there is no place to dispose or recycle them safely. We also plan to work on the design of lowtech bellows to make the natural draft micro-gasifier more convenient in use, esp. at the starting time.</font></font></font><br/>
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= Low Tech-micro-gasifiers&nbsp;: Solution for Deforestation and Health Problems Caused by Indoor Air Pollution<br/> =
  
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► [[:File:LOWTECH-MICRO-GASIFIERS AS A SOLUTION FOR DEFORESTATION AND HEALTH PROBLEMS CAUSED BY INDOOR AIR POLLUTION.pdf|Presentation: Lowtech Micro Gasifiers by Adelard Ndibalema & Andrea Berten]]<br/><font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">Tanzania faces a series of serious problems related to the heavy usage of fuel woods and charcoal in cooking, such as deforestation (especially in rural areas like Karagwe), health issues caused by [[Indoor Air Pollution (IAP)|indoor air pollution]] and great time consumption for its collection. “Micro-gasifiers” use organic wastes as fuel and have the potential to decrease the usage of fuel woods as well as the emissions, thus representing a possible solution for all these problems. This presentation described the development of a new type of microgasifier, a combination of TLUD and sawdust stove using sawdust (or in future coffee shells) and the testing methods which are being applied to prove the efficiency and the health improvements. This project is a cooperation project of Engineers Without Borders Germany/Berlin and CHEMA, an organization in Tanzania/Karagwe.</span></span></span></font></font></font></font>
  
= Low Tech-micro-gasifiers as a Solution for Deforestation and Health Problems Caused by Indoor Air Pollution ([[:File:Micro_Gasifiers|presentation]])<br/> =
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== <span style="font-size: 11pt;  font-family: Arial, sans-serif;  color: rgb(0, 0, 10)">General Information</span> ==
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">Tanzania faces a series of serious problems related to the heavy usage of fuel woods and charcoal in cooking, such as deforestation (especially in rural areas like Karagwe), health issues caused by [[Indoor Air Pollution (IAP)|indoor air pollution]] and great time consumption for its collection. “Micro-gasifiers” use organic wastes as fuel and have the potential to decrease the usage of fuel woods as well as the emissions, thus representing a possible solution for all these problems. This presentation described the development of a new type of microgasifier, a combination of TLUD and sawdust stove using sawdust (or in future coffee shells) and the testing methods which are being applied to prove the efficiency and the health improvements. This project is a cooperation project of Engineers Without Borders Germany/Berlin and CHEMA, an organization in Tanzania/Karagwe.</span></span></span></font></font></font></font><br/>
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*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">In Tanzania, people living in urban areas prefer to use firewood, but people living in rural areas prefer to use charcoal. What are the differences between these two materials?</font></font></font>
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**<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Firewood and charcoal: they are differe<font color="#00000a"><span lang="en-US">nt. Usually it is more common that people in the rural areas use firewood while people in urban areas prefer charcoal because firewood is mostly not available in bigger amounts in the cities. Also people in rural areas</span></font><font color="#00000a"><span lang="en-US"><span style="font-weight: normal">prefer to use charcoal for cooking. But many people have to collect firewood instead of using charcoal because on the one hand charcoal is expensive (the price of charcoal is higher than fire wood) and on the other hand it is not available anymore (due to law it is now forbidden to make charcoal in Tanzania for environmental reasons). In rural areas people also use grasses to cook if there is no charcoal or firewood available.</span></span></font>There is also a big fall in using fire wood when switching to biogas or using micro-gasifiers.</font></font></font>
  
 
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== <font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">General Information</font></font></font><br/> ==
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*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">What are the best approaches to collect coffee husks?</font></font></font>
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**<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- There are two coffee factories in Karagwe and behind the factory buildings themselves there are mountains of coffee husks. Usually farmers bring the coffee beans to the factory but don't take back the husks after drying process. We are currently working to find the ways to use coffee husks to apply in micro-gasifier technology to use them for cooking.</font></font></font>
  
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">In Tanzania, people living in urban areas prefer to use firewood, but people living in rural areas prefer to use charcoal. What are the differences between these two materials?</font></font></font>
+
<br/>
 
 
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Firewood and charcoal: they are differe<font color="#00000a"><span lang="en-US">nt. Usually it is more common that people in the rural areas use firewood while people in urban areas prefer charcoal because firewood is mostly not available in bigger amounts in the cities. Also people in rural areas</span></font><font color="#00000a"><span lang="en-US"><span style="font-weight: normal">prefer to use charcoal for cooking. But many people have to collect firewood instead of using charcoal because on the one hand charcoal is expensive (the price of charcoal is higher than fire wood) and on the other hand it is not available anymore (due to law it is now forbidden to make charcoal in Tanzania for environmental reasons). In rural areas people also use grasses to cook if there is no charcoal or firewood available.</span></span></font>There is also a big fall in using fire wood when switching to biogas or using micro-gasifiers.</font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">What are the best approaches to collect coffee husks?</font></font></font>
 
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- There are two coffee factories in Karagwe and behind the factory buildings themselves there are mountains of coffee husks. Usually farmers bring the coffee beans to the factory but don't take back the husks after drying process. We are currently working to find the ways to use coffee husks to apply in micro-gasifier technology to use them for cooking.</font></font></font>
+
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- The technology in using coffee husks for energetic purposes may also have the disadvantage to make people stay away from using them as materials in agricultural practices. Some people use the husks as a fertilizer or add them to the compost. <font color="#00000a"><span lang="en-US">S</span><span lang="en-US"><span style="font-style: normal"><span style="text-decoration: none"><span style="font-weight: normal">o we have to be careful of creating (no) competition. It seems to be crucial anyway that the remaining charcoal and also the ashes will be removed to the soil and be used for fertilizing.</span></span></span></span></font></font></font></font>
 +
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Also the problem of transportation needs to be faced. So the potentials to use of coffee husks for cooking will depend on the distance of e.g. A village to the coffee factory to get the husks available at the houses.</font></font></font>
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- The technology in using coffee husks for energetic purposes may also have the disadvantage to make people stay away from using them as materials in agricultural practices. Some people use the husks as a fertilizer or add them to the compost. <font color="#00000a"><span lang="en-US">S</span><span lang="en-US"><span style="font-style: normal"><span style="text-decoration: none"><span style="font-weight: normal">o we have to be careful of creating (no) competition. It seems to be crucial anyway that the remaining charcoal and also the ashes will be removed to the soil and be used for fertilizing.</span></span></span></span></font></font></font></font>
+
<br/>
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Also the problem of transportation needs to be faced. So the potentials to use of coffee husks for cooking will depend on the distance of e.g. A village to the coffee factory to get the husks available at the houses.</font></font></font>
 
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Could you please compare different kinds of wood relating to their potential use with micro-gasification?</font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Could you please compare different kinds of wood relating to their potential use with micro-gasification?</font></font></font>
 
+
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- We have not tried to compare different kinds of woods, but there are sources in literature which compare the efficiency of different kinds of wood. In Tanzania, it was not possible to compare different types of woods, but when we conduct more research in Berlin, we will be able to do this. However, literature also shows that different kind of wood does not affect strongly the result of the performance of the stove.</font></font></font>
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- We have not tried to compare different kinds of woods, but there are sources in literature which compare the efficiency of different kinds of wood. In Tanzania, it was not possible to compare different types of woods, but when we conduct more research in Berlin, we will be able to do this. However, literature also shows that different kind of wood does not affect strongly the result of the performance of the stove.</font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Does the amount of moisture influence the performance or the efficiency of the stove? Did you test it?</font></font></font>
 
 
 
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Yes, the amount of moisture influences a lot the efficiency of the stove because more energy is needed to evaporate the water. It is considered in our calculations but we had difficulties to test the moisture content of the sawdust used in Tanzania (because of missing instruments and infrastructure) that is why we estimated it. We will run more scientific tests in Berlin considering the actual amount of moisture.</font></font></font>
 
  
 
<br/>
 
<br/>
  
 +
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Does the amount of moisture influence the performance or the efficiency of the stove? Did you test it?</font></font></font>
 +
**<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Yes, the amount of moisture influences a lot the efficiency of the stove because more energy is needed to evaporate the water. It is considered in our calculations but we had difficulties to test the moisture content of the sawdust used in Tanzania (because of missing instruments and infrastructure) that is why we estimated it. We will run more scientific tests in Berlin considering the actual amount of moisture.</font></font></font>
  
= Experimental Analysis of the Thermo-chemical Conversion Processes of a Modified Sawdust-microgasifier Stove ([[:File:Sawdust_Bachelor_fabian.pdf|Presentation]])<br/> =
+
= Experimental Analysis of the Thermo-chemical Conversion Processes of a Modified Sawdust-microgasifier Stove<br/> =
 
 
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">This work wants to increase the transparency of the thermo-chemical processes in a modified sawdust-microgasifier. The temperature distribution in the fixed bed and the gas composition of the combustion gas are measured and should illustrate more details about the different processes. Connected to this there can be a theoretical optimization of the stove design.</span></font></font></font></font>
 
  
<br/>
+
► [[:File:Sawdust Bachelor fabian.pdf|Presentation: Sawdust - Microgasifier Stove]]<br/><font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">This work wants to increase the transparency of the thermo-chemical processes in a modified sawdust-microgasifier. The temperature distribution in the fixed bed and the gas composition of the combustion gas are measured and should illustrate more details about the different processes. Connected to this there can be a theoretical optimization of the stove design.</span></font></font></font></font><br/><u><font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">'''Defining the used biomass'''</span></font></font></font></font></u>:
  
<u><font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">'''Defining the used biomass'''</span></font></font></font></font></u>:
 
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Sawdust out of beech, walnut and pine wood</span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Sawdust out of beech, walnut and pine wood</span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Sorting of the particle size – three different kind of particle size distribution shall demonstrate the influence of the particle size on the behaviour of the stove.</span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Sorting of the particle size – three different kind of particle size distribution shall demonstrate the influence of the particle size on the behaviour of the stove.</span></font></font></font></font>
  
<br/>
+
<br/><u>'''<span style="font-size: 15px;  color: rgb(0, 0, 10);  font-family: Arial, sans-serif" class="Apple-style-span"><font color="#00000a"><span lang="en-US">Temperature</span></font><font color="#00000a"><span lang="en-US">distribution</span></font></span>''':</u>
  
<u>'''<span class="Apple-style-span" style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif"><font color="#00000a"><span lang="en-US">Temperature</span></font><font color="#00000a"><span lang="en-US">distribution</span></font></span>''':</u>
+
*<span style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif" class="Apple-style-span">The temperatures are measured with 8 thermocouples (typ K) at three different levels inside of the fixed bed. Hence the radial and axial distribution can be studied.</span><br/>
*<span class="Apple-style-span" style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif">The temperatures are measured with 8 thermocouples (typ K) at three different levels inside of the fixed bed. Hence the radial and axial distribution can be studied.</span><br/>
+
*<span style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif" class="Apple-style-span">The highest temperatures (~1000°C), which are attributed to exothermic combustion reactions, are measured at the bottom of the air column.</span><br/>
*<span class="Apple-style-span" style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif">The highest temperatures (~1000°C), which are attributed to exothermic combustion reactions, are measured at the bottom of the air column.</span><br/>
+
*<span style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif" class="Apple-style-span">These reactions provide the heat for endothermic gasification, pyrolysis and drying processes, which occur inside of the fixed bed.</span><br/>
*<span class="Apple-style-span" style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif">These reactions provide the heat for endothermic gasification, pyrolysis and drying processes, which occur inside of the fixed bed.</span><br/>
+
*<span style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif" class="Apple-style-span">The “pyrolysis front” (300°C) reaches after 40min the middle and after 90min the edge of the fixed bed.</span><br/>
*<span class="Apple-style-span" style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif">The “pyrolysis front” (300°C) reaches after 40min the middle and after 90min the edge of the fixed bed.</span><br/>
+
*<span style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif" class="Apple-style-span">There is a different heating-up rate of the fixed bed at the different levels, therefore the “pyrolysis front” has an axial and a radial progress.</span>
*<span class="Apple-style-span" style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif">There is a different heating-up rate of the fixed bed at the different levels, therefore the “pyrolysis front” has an axial and a radial progress.</span>
 
  
<br/>
+
<br/><u>'''<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Gas</span></font><font color="#00000a"><span lang="en-US">composition:</span></font></font></font></font>'''</u>
  
<u>'''<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Gas</span></font><font color="#00000a"><span lang="en-US">composition:</span></font></font></font></font>'''</u>
+
*<span style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif" class="Apple-style-span">Each run, three gas samples at different levels with specific temperatures are recorded from inside of the fixed bed. The temperatures are in a range of 200-600°C.</span><br/>
*<span class="Apple-style-span" style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif">Each run, three gas samples at different levels with specific temperatures are recorded from inside of the fixed bed. The temperatures are in a range of 200-600°C.</span><br/>
+
*<span style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif" class="Apple-style-span">The average combustible gas composition consists of 55-60% carbon dioxide, 20-25% carbon monoxide, 7-10% hydrogen, 6-9% methane.</span><br/>
*<span class="Apple-style-span" style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif">The average combustible gas composition consists of 55-60% carbon dioxide, 20-25% carbon monoxide, 7-10% hydrogen, 6-9% methane.</span><br/>
+
*<span style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif" class="Apple-style-span">Gas samples near the riser at the top of the stove point out a low content of carbon monoxide.</span>
*<span class="Apple-style-span" style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif">Gas samples near the riser at the top of the stove point out a low content of carbon monoxide.</span>
 
  
<br/>
+
<br/><u><font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">'''First conclusions:'''</span></font></font></font></font></u>
  
<u><font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">'''First conclusions:'''</span></font></font></font></font></u>
 
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Not every particle size is usable.</span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Not every particle size is usable.</span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">The big particle size distribution (>3,5mm) isn’t suitable for this stove design, because the fixed bed collapses after 20-30min. Due to the low density and big hollows inside the bed, it needs to be stabilize with a kind of grate for usage in this stove design.</span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">The big particle size distribution (>3,5mm) isn’t suitable for this stove design, because the fixed bed collapses after 20-30min. Due to the low density and big hollows inside the bed, it needs to be stabilize with a kind of grate for usage in this stove design.</span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">There is a different temperature distribution between the small particle size (<3,5mm) and the mix particle size distribution as a mixture of both sizes.</span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">There is a different temperature distribution between the small particle size (<3,5mm) and the mix particle size distribution as a mixture of both sizes.</span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Furthermore the heating-up rate differs with different particle sizes.</span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Furthermore the heating-up rate differs with different particle sizes.</span></font></font></font></font>
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Different thermo-chemical conversion phases take place in the sawdust stove:</span></font></font></font></font><br/><span class="Apple-style-span" style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif">Drying – Pyrolysis – Gasification – Combustion.</span>
+
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">Different thermo-chemical conversion phases take place in the sawdust stove:</span></font></font></font></font><br/><span style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif" class="Apple-style-span">Drying – Pyrolysis – Gasification – Combustion.</span>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">There is sufficient heat for char gasification, but nevertheless a bit of char always remains as leftover.</span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">There is sufficient heat for char gasification, but nevertheless a bit of char always remains as leftover.</span></font></font></font></font>
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US">A low content of carbon monoxide in the exhaust gas can be expect out of gas samples, but has to be proved during a continuous measuring during a complete stove run.</span></font></font></font></font>
+
*<font><font><font><span lang="en-US"><font color="#00000a" face="Arial, sans-serif"><span style="font-size: 11pt">A low content of carbon monoxide in the exhaust gas can be expect out of gas samples, but has to be proved during a continuous measuring during a complete stove run</span></font></span></font></font></font>
  
 
<br/>
 
<br/>
  
== <span class="Apple-style-span" style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif">General Information</span> ==
+
== <span style="color: rgb(0, 0, 10); font-family: Arial, sans-serif;  font-size: 15px;  line-height: 23px">General Information</span> ==
  
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Stove system - how to control the sawdust stove?</font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Stove system - how to control the sawdust stove?</font></font></font>
  
 
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Basically a stove can be controlled e.g. by adjusting the airflow. There is no possibility to adjust this at the sawdust at the moment; but you can close the surface and all holes to stop oxygen (primary and secondary airflow) getting inside and thus to stop the process running.</font></font></font>
 
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Basically a stove can be controlled e.g. by adjusting the airflow. There is no possibility to adjust this at the sawdust at the moment; but you can close the surface and all holes to stop oxygen (primary and secondary airflow) getting inside and thus to stop the process running.</font></font></font>
 +
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Have you tried using fans?</font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">Have you tried using fans?</font></font></font>
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- No, because we want to be independent from electricity and the question of recycling of batteries.</font></font></font>
+
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- No, because we want to be independent from electricity and the question of recycling of batteries.</font></font></font> <font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Maybe it does make sense to test the difference in efficiency by using a mechanical fan.</font></font></font>
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Maybe it does make sense to test the difference in efficiency by using a mechanical fan.</font></font></font>
 
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">With this design, do you have problem with possible burns to people surrounding: the temperature is really hot outside the stove, do people get hurt?</font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">With this design, do you have problem with possible burns to people surrounding: the temperature is really hot outside the stove, do people get hurt?</font></font></font>
  
 
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Due to the design with two layers, the outer part always remains much cooler then inside and remains handable.</font></font></font>
 
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Due to the design with two layers, the outer part always remains much cooler then inside and remains handable.</font></font></font>
 +
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">What are the implication for Tanzania?</font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">What are the implication for Tanzania?</font></font></font>
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Open a workshop so that more people will have knowledge and experience to build and use the stoves. The dimension, design and other information will be published (as creative commons) so that people are informed. Also we want to be part of a development&production network for micro-gasifiers. Also Paul Anderson shared all the information about his stoves, e.g. Mwoto stove, to spread the idea of micro-gasifiers.</font></font></font>
+
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">- Open a workshop so that more people will have knowledge and experience to build and use the stoves. The dimension, design and other information will be published (as creative commons) so that people are informed. Also we want to be part of a development&production network for micro-gasifiers. Also Paul Anderson shared all the information about his stoves, e.g. Mwoto stove, to spread the idea of micro-gasifiers.</font></font></font> <font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">The technology of micro-gasifiers is quite new. A lot of the knowledge sharing is based on creative commons and thus community-based. Commercialization only started recently within the last 10 or 15 years.</font></font></font><br/>
 
 
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt">The technology of micro-gasifiers is quite new. A lot of the knowledge sharing is based on creative commons and thus community-based. Commercialization only started recently within the last 10 or 15 years.</font></font></font>
 
 
 
<br/>
 
 
 
 
 
= The concept of “Swirl Flow” ("Design-space for lowtech-ideas" at TU Berlin) =
 
 
 
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">The creation of rotational flow is a common technique in combustion engineering to enhance the mixing of fuel and air and stabilize the flame. Micro-Gasifiers utilizing this technique are equally easy to build and possibly offer a more stable flame under a wider range of conditions. This talk explained the physics of fluid dynamics and how the design of the stoves affects the air flow, mixing and stability of the flame.</span></span></span></font></font></font></font>
 
  
<br/>
+
= The Concept of “Swirl Flow” ("Design-space for Lowtech-ideas" at TU Berlin) =
  
<br/>
+
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">The creation of rotational flow is a common technique in combustion engineering to enhance the mixing of fuel and air and stabilize the flame. Micro-Gasifiers utilizing this technique are equally easy to build and possibly offer a more stable flame under a wider range of conditions. This talk explained the physics of fluid dynamics and how the design of the stoves affects the air flow, mixing and stability of the flame.</span></span></span></font></font></font></font><br/>
  
 
== General Information ==
 
== General Information ==
Line 167: Line 155:
  
 
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">- The rotational air flow of the secondary air cools the outer tin, so it is even safer to handle than in other stove designs.</span></span></span></font></font></font></font>
 
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">- The rotational air flow of the secondary air cools the outer tin, so it is even safer to handle than in other stove designs.</span></span></span></font></font></font></font>
 +
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-weight: normal">How much research has been done on this topic?</span></span></font></font></font></font>
 
*<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-weight: normal">How much research has been done on this topic?</span></span></font></font></font></font>
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">- Until now, only a few proof of concept stoves have been built, but they look promising and further research is due.</span></span></span></font></font></font></font>
+
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><span lang="en-US"><span style="font-style: normal"><span style="font-weight: normal">- Until now, only a few proof of concept stoves have been built, but they look promising and further research is due.</span></span></span></font></font></font></font><br/>[[File:Testing microgasifiers.jpg|thumb|center|400px|Testing Micro Gasifiers|alt=Testing microgasifiers.jpg]]
  
 
<br/>
 
<br/>
  
<font size="4" face="Arial, sans-serif" color="#00000A" class="Apple-style-span"><span style="font-size: 15px" class="Apple-style-span"></span></font>[[File:Testing microgasifiers.jpg|border|left|238px|The|alt=Testing microgasifiers.jpg]]
 
  
<font color="#00000a"><font face="Arial, sans-serif"><font size="2" style="font-size: 11pt"><font color="#00000a"><font size="2">T</font><span lang="en-US">he "Top-Lit Up-Draft"-Design (TLUD) built out of old cans and a modified</span></font></font></font></font><span class="Apple-style-span" style="font-size: 15px; color: rgb(0, 0, 10); font-family: Arial, sans-serif">sawdust stove built in Tanzania.</span>
+
= Further Information =
  
<br/>
+
*<span style="line-height: normal;  font-family: arial" class="Apple-style-span">'''Anderson''', P. S., Reed, T. B. (2004): ''Biomass Gasification: Clean Residential Stoves, Commercial Power Generation, and Global Impacts'', [http://www.bioenergylists.org/stovesdoc/Anderson/GasifierLAMNET.pdf http://www.bioenergylists.org/stovesdoc/Anderson/GasifierLAMNET.pdf] (seen 18.8.2010).</span>
 +
*'''Anderson''', P. S., Reed, T. B. (2007): ''Micro-Gasification: What it is and why it works'', in Boiling Point No 35, p. 34-37.
 +
*'''Anderson''', P. S. (2009): ''Construction Plans for the “Champion-2008” TLUD Gasifier Cookstove (including operational instructions)'', [http://bioenergylists.org http://bioenergylists.org] (seen 18.8.2010).
 +
*'''Anderson''', P. S. (2011): ''TChar Technology for Cookstoves: Part B: Construction, [http://drtlud.com/ http://drtlud.com/] ''(seen 16.12.2011).
 +
*'''IBI '''(2011): ''Biochar-Producing Stoves to Benefit Climate, Health, and Soil'', [http://www.biochar- http://www.biochar-] international.org/technology/stoves (Zugriff am 14.5.2011).
 +
*'''McLaughlin''', H. (2010): ''1G Toucan TLUD for Biochar Production'', Alterna Biocarbon Inc., [http://terrapreta.bioenergylists.org/files/1G Toucan TLUD for Biochar Jan 2 http://terrapreta.bioenergylists.org/files/1G Toucan TLUD for Biochar Jan 2] 010%20-%20final_0.pdf (Zugriff am 17.8.2011).
 +
*'''Roth '''[[:File:Micro Gasification 2.0 Cooking with gas from dry biomass.pdf|Micro-gasification: Cooking with gas from biomass - An introduction to the concept and the applications of wood-gas burning technologies for cooking]], Hrsg, Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ), HERA - Poverty-oriented Energy Service, Eschborn.
 +
*Please find more files to download here: [https://www.isis.tu-berlin.de/mod/resource/view.php?id=228195&subdir=/microgasifier www.isis.tu-berlin.de]<br/>
 +
*[[Cooking_with_Woodgas|Cooking with Woodgas]] article on energypedia
  
 
<br/>
 
<br/>
Line 183: Line 179:
 
<br/>
 
<br/>
  
= References =
 
  
This article details the proceedings of the session "Micro-Gasifier" at the <span style="line-height: normal" class="Apple-style-span">[https://energypedia.info/wiki/Micro_Perspectives_for_Decentralized_Energy_Supply_-_Conference_2013 Micro Perspectives for Decentralized Energy Supply Conference - 2013] at University of Technology in Berlin with the following oral presentations:</span>
+
= References<br/> =
*'''<font size="2"><font face="Liberation Serif, serif">Betzl, J.</font></font>'''<font face="Liberation Serif, serif"><font size="2" style="font-size: 11pt">'''<span style="font-weight: normal">:</span>'''''<span style="font-weight: normal">What are micro-gasifiers? // Short story about the history of micro-gasification (</span>''</font></font><u>[http://www.kompostkreis.blogspot.de/ www.kompostkreis.de])</u>
 
*<font face="Liberation Serif, serif"><font size="2" style="font-size: 11pt"><span style="font-weight: normal">'''Krause, A.''': </span>''<span style="font-weight: normal">What is micro-gasification? // About the process and products<br/></span>''<span style="font-weight: normal">With special thanks to Mrs. Roth and Mr. Anderson/Dr. TLUD whose slides are used in the presentation with permission.</span></font></font>
 
*'''Ndibalema, A. and Berten, '''<font face="Liberation Serif, serif"><font size="2" style="font-size: 11pt"><span style="font-weight: normal">'''A.:''' ''Low tech-micro-gasifiers as a solution for deforestation and health problems caused by indoor air pollution'' (Practitioner<font size="2">'s paper)</font></span></font></font>
 
*'''Schmid, F.: '''''<font face="Liberation Serif, serif"><font size="2" style="font-size: 11pt"><span style="font-style: normal"><span style="font-weight: normal">Experimental Analysis of the thermo-chemical conversion processes of a modified sawdust-microgasifier stove (</span></span><span style="font-style: normal"><span style="font-weight: normal">Bachelorthesis)</span></span></font></font>''
 
*'''Dik, M.: '''<font face="Liberation Serif, serif"><font size="2" style="font-size: 11pt">''<span style="font-weight: normal">The concept of “Swirl Flow”</span>''</font></font>
 
  
<br/>
+
This article details the proceedings of the session "Micro-Gasifier" at the [[Micro Perspectives for Decentralized Energy Supply - Conference 2013|Micro Perspectives for Decentralized Energy Supply Conference - 2013]] at University of Technology in Berlin with the following oral presentations:
  
Other Paper's submitted and accepted for the conference without oral presentation:
+
*'''Betzl, J.'''''What are micro-gasifiers? // Short story about the history of micro-gasification ([http://www.kompostkreis.blogspot.de/ www.kompostkreis.de])''
*'''Vable, A. and Jain, R.: '''<font face="Liberation Serif, serif"><font size="2" style="font-size: 11pt">''<span style="font-weight: normal"><span style="background: #ffffff">Village-Level Pine Needle Gasification to Meet Rural Electrical and Cooking Energy Needs in the Indian Central Himalayas</span></span>''</font></font>
+
*'''Krause, A.''': What is micro-gasification? // About the process and products<br/>''With special thanks to Mrs. Roth and Mr. Anderson/Dr. TLUD whose slides are used in the presentation with permission.''
*'''Iddphone, R. '''''et al.: ''<font face="Liberation Serif, serif"><font size="2" style="font-size: 11pt">''<span style="font-weight: normal"><span style="background: #ffffff">The Effect of Using Biomass Gasification as Source of Energy to Small Scale Bio-Ethanol Production</span></span>''</font></font>
+
*'''Ndibalema, A. and Berten, A.: '''''Low tech-micro-gasifiers as a solution for deforestation and health problems caused by indoor air pollution'' (Practitioner's paper)
 +
*'''Schmid, F.: '''''Experimental Analysis of the thermo-chemical conversion processes of a modified sawdust-microgasifier stove (Bachelorthesis)''
 +
*'''Dik, M.: '''''The concept of “Swirl Flow”''
  
<br/>
+
<br/>Other Paper's submitted and accepted for the conference without oral presentation:
  
Further References for micro-gasifiers are:
+
*'''Vable, A. and Jain, R.: '''''Village-Level Pine Needle Gasification to Meet Rural Electrical and Cooking Energy Needs in the Indian Central Himalayas''
*<span style="line-height: normal; font-family: Arial" class="Apple-style-span">'''Anderson''', P. S., Reed, T. B. (2004): ''Biomass Gasification: Clean Residential Stoves, Commercial Power Generation, and Global Impacts'', [http://www.bioenergylists.org/stovesdoc/Anderson/GasifierLAMNET.pdf http://www.bioenergylists.org/stovesdoc/Anderson/GasifierLAMNET.pdf] (seen 18.8.2010).</span>
+
*'''Iddphone, R. '''''et al.: '': The Effect of Using Biomass Gasification as Source of Energy to Small Scale Bio-Ethanol Production
*'''Anderson''', P. S., Reed, T. B. (2007): ''Micro-Gasification: What it is and why it works'', in Boiling Point No 35, p. 34-37.
 
*'''Anderson''', P. S. (2009): ''Construction Plans for the “Champion-2008” TLUD Gasifier Cookstove (including operational instructions)'', [http://bioenergylists.org http://bioenergylists.org] (seen 18.8.2010).
 
*'''Anderson''', P. S. (2011): ''TChar Technology for Cookstoves: Part B: Construction, [http://drtlud.com/ http://drtlud.com/] ''(seen 16.12.2011).
 
*'''IBI '''(2011): ''Biochar-Producing Stoves to Benefit Climate, Health, and Soil'', [http://www.biochar- http://www.biochar-] international.org/technology/stoves (Zugriff am 14.5.2011).
 
*'''McLaughlin''', H. (2010): ''1G Toucan TLUD for Biochar Production'', Alterna Biocarbon Inc., [http://terrapreta.bioenergylists.org/files/1G Toucan TLUD for Biochar Jan 2 http://terrapreta.bioenergylists.org/files/1G Toucan TLUD for Biochar Jan 2] 010%20-%20final_0.pdf (Zugriff am 17.8.2011).
 
*'''Roth '''(2011): ''Micro-gasification: Cooking with gas from biomass - An introduction to the concept and the applications of wood-gas burning technologies for cooking'', Hrsg, Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ), HERA - Poverty-oriented Energy Service, Eschborn.
 
  
<br/>
+
<br/><references />
 
 
Please find more files to download here: [https://www.isis.tu-berlin.de/mod/resource/view.php?id=228195&subdir=/microgasifier www.isis.tu-berlin.de]<br/>
 
  
 +
[[Category:Cookstoves]]
 +
[[Category:Gasifier]]
 
[[Category:Tanzania]]
 
[[Category:Tanzania]]
[[Category:Cookstoves]]
 

Latest revision as of 11:51, 19 December 2016

Overview

The so-called "micro-gasifier"

Rocket stove, Sawdust-microgasifier, TLUD-microgasifier (from left to right)
Stove Types: Rocket stove, Sawdust-microgasifier, TLUD-microgasifier (from left to right)

stoves convert dry biomass to wood gas and charcoal before the gas is burned. This gasification process needs heat and the absence of oxygen. The flame which offers sufficient heat for cooking is fed by the ascending wood gas and oxygen. This simple principle is used in a variety of contexts with different aims which mostly reflect local conditions.The aim was to discuss the impact of changes in the stove-design on the performance of the stove with special focus on type of substrate in use, efficiency, emissions, handling and other unexpectable side effects.The presentation included different models of microgasifiers and substrates which were presented by the participants in the room.




History of Micro-gasification

Asdescendants of the steam-engines, microgasifiers went through different stages with changing names, models and usage. Gasifiers of smaller size and weight conquered individuals lives throughmobility, cooking and agriculture. Woodgas drove millions of vehicles equipped with Imbert-generators during the 1930s and 40s in Europe. After propagation trough international cooperation since the 80s many households in Africa nowadays use microgasifiers as efficient cooking-stoves. Charcoal is a product of pyrolysis and stabilizes a highly fertile soil called Terra preta – an anthropogenic product rediscovered and reconstructed in recent years. Terra preta combines by-products of micro-gasifiers with recycling processes which form the basis of an ecological and social sustainable economy.

Process and Products

Presentation: Micro Gasifiers Ariane Krause presentation
Micro Gasifiers
The challenge:

  • Elimination of unacceptable emissions of CO and particles and pre-dominant use of firewood;
  • Realize low-cost and user-friendly cookstoves to provide household-energy;
  • Use wood and other dry biomass materials efficiently: with micro-gasifiers biomass is used with little emissions only to produce heat but at the same time also some charcoal is produced in little amounts.


Technical and chemical processes:

  • Differences of woodgas as a product of a heat-related process and the use of dry biomass and biogas as a product from biochemical digestion of wet biomass were explained.
  • Gasifiers” are devices in which the dry biomass is transformed into combustible gases on processes distinctly and controllably separate in time and location from the eventual combustion of the gases.
  • Comparison of the processes: they happen one after the other or simultaneously when biomass is burnt directly or gasified first.
  • Explanation of the stove's design in relation with the processes; what is happening in which part of the oven according to the design of Paal Wendelbo and Paul Anderson called TLUD standing for “Top-Lit UpDraft”
  • There are two zones: (1) gasification of fire wood where pyrolysis happens (Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen)and (2) combustion of woodgas; there are primary and secondary airflow respectively. As for the gasificiation a little amount of oxygen is needed and for the combustion sufficient oxygen needs to be on spot, the secondary airflow is bigger than the primary airflow.


Characteristics of the products:

  • Emissions of Carbon Monoxide (CO) and Particulate Matter (PM) from micro-gasifiers are comparatively low to other cookingstoves
  • With micro-gasification also a valuable by-product is produced: approx. 10% of the carbon that was contained in the biomass will be thermally stabilized and bounded in little amounts of charcoal that remain in the stove. There are stove-designs that also use the charcoal produced for thermal purposes and thus burn it. Another approach would be to use the charcoal as so-called “biochar” which means to add the charcoal to compost pits or directly to the soil to improve soil quality after the principles of “Terra Preta”


General Information

  • How large can you build the model with that simple structure?
    • - No scientific answer is known to the speakers, but the largest personally observed one is in operation at ATB,Leibniz Institute of Agricultural Engineering in Potsdam-Barnim and has the size of an oil barrel. The model works well. The advantage of micro-gasifiers is that they are easy to build only with resources that are available on spot to be used for constructing. So the size may depend on the available materials also.
    • - There is also thermo-chemical process named “gasification” which is realized mostly in swirling beds and ment for larger scale implementations. Experiments at TU Berlin are done e.g. at the chair for Energy Process Engineering and Conversion Technologies for Renewable Energies (FG EVUR). But here we focus on decentralized and small-scale realization of gasificiation in micro-gasifiers.
    • - There is also a minimum size as well so that the volume of substrate should be at least 300 ml. Otherwise heat losses at the stove's surface are too big compared to the produced heat inside and the stove will not run properly.


  • What are health implications?
    • - There are certain improvements in the new design: the CO level falls extremely, also for the PM (clean emissions, few smoke)


  • How can we prevent the users from inhaling carbon monoxide?
    • - Design: Makesure to have sufficient secondary air


  • Have you compared the effectiveness and efficiency of biogas, wood gas and LPG?
    • - We personally not yet. But there is research done to compare the efficiency of biogas, wood gas and maybe also LPG. For example the Centre for Research in Energy and Energy Conservation (CREEC) at the College of Engineering, Design, Art and Technology (CEDAT) at Makerere University, Kampala, is working on that. It is also our plan to set up a closer cooperation between TU Berlin (esp. Postgraduate program “Microenergy Systems”) in CREEC to continue to work on this in the future.
    • - We started with water boiling tests to compare the demand of resource needed with a particular cooking method to boil a certain amount of water (and thus offer a specific amount of thermal energy to use) to see how much wood we would have used with open fire in comparison with the improved cooking method. We also want to compare this to “rocket stoves” which uses charcoal. But then we also have to account the process of making charcoal from wood first. There will be a more information about this in another presentation later.


  • How old is the TLUD system?
    • - It was first invented in the 1980s, but the first commercial use started in 2000 (so it is a quite new technology)


  • Could the design be improved by using a fan?
    • - There are two designs possible concerning the air flow: a forced air flow using fans or natural air flow only using the differences in temperature and thus in density of the air. Today we only show self-made lowtech designs with natural air flow. We decided for this because we wanted to be independent from electricity. You could easily use nearly empty batteries to operate a fan to have an improved forced airflow, but the problems come when the batteries are empty and there is no place to dispose or recycle them safely. We also plan to work on the design of lowtech bellows to make the natural draft micro-gasifier more convenient in use, esp. at the starting time.


Low Tech-micro-gasifiers : Solution for Deforestation and Health Problems Caused by Indoor Air Pollution

Presentation: Lowtech Micro Gasifiers by Adelard Ndibalema & Andrea Berten
Tanzania faces a series of serious problems related to the heavy usage of fuel woods and charcoal in cooking, such as deforestation (especially in rural areas like Karagwe), health issues caused by indoor air pollution and great time consumption for its collection. “Micro-gasifiers” use organic wastes as fuel and have the potential to decrease the usage of fuel woods as well as the emissions, thus representing a possible solution for all these problems. This presentation described the development of a new type of microgasifier, a combination of TLUD and sawdust stove using sawdust (or in future coffee shells) and the testing methods which are being applied to prove the efficiency and the health improvements. This project is a cooperation project of Engineers Without Borders Germany/Berlin and CHEMA, an organization in Tanzania/Karagwe.

General Information

  • In Tanzania, people living in urban areas prefer to use firewood, but people living in rural areas prefer to use charcoal. What are the differences between these two materials?
    • - Firewood and charcoal: they are different. Usually it is more common that people in the rural areas use firewood while people in urban areas prefer charcoal because firewood is mostly not available in bigger amounts in the cities. Also people in rural areasprefer to use charcoal for cooking. But many people have to collect firewood instead of using charcoal because on the one hand charcoal is expensive (the price of charcoal is higher than fire wood) and on the other hand it is not available anymore (due to law it is now forbidden to make charcoal in Tanzania for environmental reasons). In rural areas people also use grasses to cook if there is no charcoal or firewood available.There is also a big fall in using fire wood when switching to biogas or using micro-gasifiers.


  • What are the best approaches to collect coffee husks?
    • - There are two coffee factories in Karagwe and behind the factory buildings themselves there are mountains of coffee husks. Usually farmers bring the coffee beans to the factory but don't take back the husks after drying process. We are currently working to find the ways to use coffee husks to apply in micro-gasifier technology to use them for cooking.


  • - The technology in using coffee husks for energetic purposes may also have the disadvantage to make people stay away from using them as materials in agricultural practices. Some people use the husks as a fertilizer or add them to the compost. So we have to be careful of creating (no) competition. It seems to be crucial anyway that the remaining charcoal and also the ashes will be removed to the soil and be used for fertilizing.
  • - Also the problem of transportation needs to be faced. So the potentials to use of coffee husks for cooking will depend on the distance of e.g. A village to the coffee factory to get the husks available at the houses.


  • Could you please compare different kinds of wood relating to their potential use with micro-gasification?
  • - We have not tried to compare different kinds of woods, but there are sources in literature which compare the efficiency of different kinds of wood. In Tanzania, it was not possible to compare different types of woods, but when we conduct more research in Berlin, we will be able to do this. However, literature also shows that different kind of wood does not affect strongly the result of the performance of the stove.


  • Does the amount of moisture influence the performance or the efficiency of the stove? Did you test it?
    • - Yes, the amount of moisture influences a lot the efficiency of the stove because more energy is needed to evaporate the water. It is considered in our calculations but we had difficulties to test the moisture content of the sawdust used in Tanzania (because of missing instruments and infrastructure) that is why we estimated it. We will run more scientific tests in Berlin considering the actual amount of moisture.

Experimental Analysis of the Thermo-chemical Conversion Processes of a Modified Sawdust-microgasifier Stove

Presentation: Sawdust - Microgasifier Stove
This work wants to increase the transparency of the thermo-chemical processes in a modified sawdust-microgasifier. The temperature distribution in the fixed bed and the gas composition of the combustion gas are measured and should illustrate more details about the different processes. Connected to this there can be a theoretical optimization of the stove design.
Defining the used biomass:

  • Sawdust out of beech, walnut and pine wood
  • Sorting of the particle size – three different kind of particle size distribution shall demonstrate the influence of the particle size on the behaviour of the stove.


Temperaturedistribution:

  • The temperatures are measured with 8 thermocouples (typ K) at three different levels inside of the fixed bed. Hence the radial and axial distribution can be studied.
  • The highest temperatures (~1000°C), which are attributed to exothermic combustion reactions, are measured at the bottom of the air column.
  • These reactions provide the heat for endothermic gasification, pyrolysis and drying processes, which occur inside of the fixed bed.
  • The “pyrolysis front” (300°C) reaches after 40min the middle and after 90min the edge of the fixed bed.
  • There is a different heating-up rate of the fixed bed at the different levels, therefore the “pyrolysis front” has an axial and a radial progress.


Gascomposition:

  • Each run, three gas samples at different levels with specific temperatures are recorded from inside of the fixed bed. The temperatures are in a range of 200-600°C.
  • The average combustible gas composition consists of 55-60% carbon dioxide, 20-25% carbon monoxide, 7-10% hydrogen, 6-9% methane.
  • Gas samples near the riser at the top of the stove point out a low content of carbon monoxide.


First conclusions:

  • Not every particle size is usable.
  • The big particle size distribution (>3,5mm) isn’t suitable for this stove design, because the fixed bed collapses after 20-30min. Due to the low density and big hollows inside the bed, it needs to be stabilize with a kind of grate for usage in this stove design.
  • There is a different temperature distribution between the small particle size (<3,5mm) and the mix particle size distribution as a mixture of both sizes.
  • Furthermore the heating-up rate differs with different particle sizes.
  • Different thermo-chemical conversion phases take place in the sawdust stove:
    Drying – Pyrolysis – Gasification – Combustion.
  • There is sufficient heat for char gasification, but nevertheless a bit of char always remains as leftover.
  • A low content of carbon monoxide in the exhaust gas can be expect out of gas samples, but has to be proved during a continuous measuring during a complete stove run


General Information

  • Stove system - how to control the sawdust stove?

- Basically a stove can be controlled e.g. by adjusting the airflow. There is no possibility to adjust this at the sawdust at the moment; but you can close the surface and all holes to stop oxygen (primary and secondary airflow) getting inside and thus to stop the process running.

  • Have you tried using fans?

- No, because we want to be independent from electricity and the question of recycling of batteries. - Maybe it does make sense to test the difference in efficiency by using a mechanical fan.

  • With this design, do you have problem with possible burns to people surrounding: the temperature is really hot outside the stove, do people get hurt?

- Due to the design with two layers, the outer part always remains much cooler then inside and remains handable.

  • What are the implication for Tanzania?

- Open a workshop so that more people will have knowledge and experience to build and use the stoves. The dimension, design and other information will be published (as creative commons) so that people are informed. Also we want to be part of a development&production network for micro-gasifiers. Also Paul Anderson shared all the information about his stoves, e.g. Mwoto stove, to spread the idea of micro-gasifiers. The technology of micro-gasifiers is quite new. A lot of the knowledge sharing is based on creative commons and thus community-based. Commercialization only started recently within the last 10 or 15 years.

The Concept of “Swirl Flow” ("Design-space for Lowtech-ideas" at TU Berlin)

The creation of rotational flow is a common technique in combustion engineering to enhance the mixing of fuel and air and stabilize the flame. Micro-Gasifiers utilizing this technique are equally easy to build and possibly offer a more stable flame under a wider range of conditions. This talk explained the physics of fluid dynamics and how the design of the stoves affects the air flow, mixing and stability of the flame.

General Information

  • What are possible other side-effects?

- The rotational air flow of the secondary air cools the outer tin, so it is even safer to handle than in other stove designs.

  • How much research has been done on this topic?

- Until now, only a few proof of concept stoves have been built, but they look promising and further research is due.

Testing microgasifiers.jpg
Testing Micro Gasifiers



Further Information




References

This article details the proceedings of the session "Micro-Gasifier" at the Micro Perspectives for Decentralized Energy Supply Conference - 2013 at University of Technology in Berlin with the following oral presentations:

  • Betzl, J.What are micro-gasifiers? // Short story about the history of micro-gasification (www.kompostkreis.de)
  • Krause, A.: What is micro-gasification? // About the process and products
    With special thanks to Mrs. Roth and Mr. Anderson/Dr. TLUD whose slides are used in the presentation with permission.
  • Ndibalema, A. and Berten, A.: Low tech-micro-gasifiers as a solution for deforestation and health problems caused by indoor air pollution (Practitioner's paper)
  • Schmid, F.: Experimental Analysis of the thermo-chemical conversion processes of a modified sawdust-microgasifier stove (Bachelorthesis)
  • Dik, M.: The concept of “Swirl Flow”


Other Paper's submitted and accepted for the conference without oral presentation:

  • Vable, A. and Jain, R.: Village-Level Pine Needle Gasification to Meet Rural Electrical and Cooking Energy Needs in the Indian Central Himalayas
  • Iddphone, R. et al.: : The Effect of Using Biomass Gasification as Source of Energy to Small Scale Bio-Ethanol Production