Automated Two-Blower Cooking Stove

This application claims the benefit of U.S. Provisional Application No. 63/645,830 filed May 10, 2024.

The present invention relates to thermochemical, electrical, pneumatic, and mechanical systems and methods. More specifically, the present invention relates to thermodynamic, electrical, pneumatic, and mechanical systems and methods for biomass combustion.

Every day, nearly three billion people in the developing world are forced to inhale the toxic fumes caused by cooking their dinner. These emissions are a leading cause of disease and death and are the number one source of greenhouse gas emissions per household in developing countries. The production of these cooking fuels also has devastating impacts on the environment. Unfortunately, cleaner alternatives such as propane (LPG) are far too expensive and tend to create a continued reliance on unsustainable fossil fuels.

Biomass cookstoves have been accepted as a viable alternative. A biomass cookstove is a type of cooking appliance that uses biomass fuels for cooking. A biomass cookstove is designed to burn organic materials (biomass) such as wood, agricultural waste, wood pellets, or even dried animal dung to generate heat for cooking. These stoves provide a cleaner and more efficient way to cook meals, reducing reliance on traditional cooking methods like open fires or inefficient cookstoves.

Biomass stoves come in various designs and configurations. Some common types include: wood-burning stoves that use logs or wood chips as fuel; pellet stove that burn compressed wood pellets; gasifier stoves that convert biomass into a combustible gas for cooking; rocket stoves that are known for their efficient combustion and minimal smoke production; improved cookstoves designed to reduce fuel consumption and emissions; briquette stoves that use biomass briquettes made from compressed organic matter and dung stoves that utilize dried animal dung as fuel.

By promoting cleaner and more efficient cookstoves, it has been recognized that we can improve health outcomes, reduce greenhouse gas emissions, and enhance livelihoods. Organizations like the Global Alliance for Clean Cookstoves work toward creating a thriving market for these solutions, aiming for sustained adoption and better cooking products. Hence, these stoves not only cook food but also contribute to broader environmental and social goals. Biomass cookstoves play a particularly crucial role in developing countries, where traditional cooking methods can lead to indoor air pollution, health issues, and deforestation.

Existing cleaner biomass stove solutions are cumbersome and have failed to penetrate the market. One shortcoming of conventional biomass cookstoves is that such cookstoves generally only produce a useful cooking flame during a fresh fuel phase in which the fuel still contains hydrogen and oxygen atoms. During combustion, hydrogen and oxygen are driven off by pyrolysis and only pure carbon and trace minerals remain. During this “Char Phase,” state of the art biomass cookstoves fail to hold a steady and usable heat output, and drop off in thermal output, to the point where the stove can no longer boil or even simmer water. This typically represents as much as a thirty percent loss of useful cooking time and wasted money and effort for the user.

Unfortunately, leading biomass cookstoves are not yet clean or convenient enough for users to transition away from charcoal and petroleum. Biomass stoves such as the Top Lit Updraft (TLUD) are a well-established solution for generating heat cleanly in comparison to a three stone hearth, charcoal cookstove or other biomass cooking apparatus and method. TLUD cookstoves achieve decent emissions and efficiency while also being convenient and granting access to renewable fuel sources.

Disadvantages of typical TLUD cookstoves are that such cookstoves are less convenient, have higher emissions and have a limited heat range compared to liquid or gas cookstoves. Many cookstoves are unable to reliably report their usage for market feedback and carbon credit reporting. Further, many TLUD stoves only use a single variable speed blower and a fixed ratio of primary and secondary air with no sensor feedback, this results in a stove that runs well only for a narrow range of heat outputs and only during the fresh fuel phase of combustion.

Because of the limitations of food types that may be cooked with a biomass pellet stove, users will often defer to dirtier or less sustainable fuel types, such as charcoal, liquid propane gas and kerosene, even when biomass pellets are available. Hence, cooking applications for these stoves are limited due to poor control over power output, leading to inefficient combustion and higher than recommended pollution levels. As a result, the potential offset of carbon emissions and the positive health impacts of cleaner cooking are yet to be fully realized.

To expand the impact of sustainably produced biomass pellet stoves, the stove itself must be generally practical and accommodate all cooking requirements that one might expect from an open flame stove. Thus, a need remains in the art for a cleaner environmental and biological biomass stove solution. More particularly, there is a need in the art for a suitable cooking device that burns biomass cleanly and efficiently preferably with continuous, automatic, accurate reporting of fuel usage for carbon credits. Such features would have the potential to unlock a global transition from unsustainable cooking to sustainable fuel sourcing and with correct agricultural/forestry practices be an accelerant of regenerative cooking fuel deployment.

The need in the art is addressed by the high efficiency automated low emission biomass cookstove of the present invention. The system is fueled by sustainable or regenerative biomass sources and generates high value, durable carbon credits. In the illustrated embodiment the inventive cookstove comprises a housing, a combustion assembly inside the housing, dual air flow passageways disposed at least partially within the housing for communicating air flow from outside the housing to said combustion assembly, and a control system for automatically and dynamically adjusting relative air flow between the primary and secondary air flow passageways.

A two-blower automated stove with sensors is thus disclosed that dynamically adjusts independent air flows and optimizes for the fresh fuel phase, and also manages air through a transitional phase, and then a char phase.

The control system includes temperature sensors, a processor and a software protocol for execution by the microprocessor to operate the cookstove to substantially increase efficiency and decrease emissions. In some embodiments, the invention further includes software and a transceiver for transmitting sensor data reports for carbon credits.

Illustrative embodiments and exemplary applications will now be described with reference to the accompanying drawings. A system is disclosed for clean combustion of biomass for cooking and heating, a control system operationally coupled to the cookstove, and sensor data reporting that generates carbon credits and tracks utilization and biomass consumption. “Clean” means biomass technologies for cooking, including biomass stoves, that meet the definition of “Clean” as defined by the World Health Organization, which definition is accessible on the Internet at https://www.who.int/tools/clean-household-energy-solutions-toolkit/module-7-defining-clean. In accordance with the present teachings, a two-blower automated stove with sensors is taught that dynamically adjusts air independent air flows and optimizes for the fresh fuel phase, but also manages air through the transitional phase, and then the char phase.

As noted above, biomass stoves such as the TLUD are a known solution for generating heat cleanly relative to a three stone hearth, charcoal cookstove or other biomass cooking apparatus and method. TLUD cookstoves achieve decent emissions and efficiency while also being convenient and granting access to renewable fuel sources. However, TLUD cookstoves are less convenient, have higher emissions and have a limited heat range compared to liquid or gas cookstoves. Further, many cookstoves are unable to reliably report usage data for market feedback and carbon credit reporting.

Many TLUD stoves only use a single variable speed blower and a fixed ratio of primary and secondary air with no sensor feedback, this results in a stove that runs well only for a narrow range of heat outputs and only during the fresh fuel phase of combustion. Because of the limitations of food types that may be cooked with a biomass pellet stove, users will often defer to dirtier or less sustainable fuel types such as charcoal, liquid propane gas, and kerosene, even when biomass pellets are available. To expand the impact of sustainably produced biomass pellet stoves, the stove itself must be generally practical and accommodate all cooking requirements that one might expect from an open flame stove.

Hence, it would be advantageous to provide a biomass cookstove that efficiently and effectively converts biomass to clean useful heat for cooking or other applications while generating reports for credible carbon credits and customer usage data. These features have great potential to unlock a global transition from unsustainable cooking to sustainable fuel sourcing and, with correct agricultural/forestry practices, serve as an accelerant of regenerative cooking fuel deployment.

In accordance with the present teachings, a two-blower automated stove with sensors is disclosed that dynamically adjusts air independent air flows to optimize fuel combustion during the fresh fuel phase, an intermediate transition phase, and a carbonized fuel (char) phase.

An automated low emission high efficiency biomass cookstove, as seen in, comprises a housing assembly, flame well, cooking implement (e.g., a pot), adjustment dial, lift handleand user interface. With additional reference to, it can be seen that a combustion assemblyis disposed inside the housing assembly. The housing assemblycomprises a housing shell, top lid, user interfaceand skid plate, and a combustion cuphaving a combustion cup base. Primary and secondary air flow passageways,are disposed at least partially within the housing for communicating air flow from outside the housingto the combustion cupand comprise a control system for automatically and dynamically adjusting relative air flow between the primary and secondary air flow passageways to optimize performance of the stove.

As seen in, the combustion assemblyis nested inside housing. The primary air blowerconveys air through the primary air flow passagewayinto the primary air holesfor primary combustion of fuel in the combustion cup, such as biomass. Primary combustion is what generates the gas that is combusted at the top of the combustion cup. The secondary air blowerconveys air through the secondary air flow passagewayinto the secondary air holes(see) for secondary combustion in the flame well. Secondary combustion generates the visible cooking flame in the flame wellat the top of the combustion cupby combustion of the gases produced from primary combustion. The diffuserdirects the gases that have flowed upward from the primary combustion outside the combustion cupto the flame wellto mix it thoroughly with secondary air to substantially improve combustion having lower emissions. Enclosure air flowis driven by heat convection and enters the cooling air holesin skid plateand exits through ventilation slotsat the top of the housing. The passive and/or active cooling air keeps the enclosure surface temperatures low for safety of the user and prevents electronic components from overheating.

is a high-level representation of components of the fuel combustion that occurs in the combustion cup. Fresh fuelis disposed at the bottom of the combustion cup. The top level of the fuel is undergoing pyrolysis, at, the product of which is combusted in the primary combustion area, at. Pyrolysis and combustion product a layer of charatop the fresh fuel, and gaseswhich flow upward into the flame welldefined by diffuserfor secondary combustion.

With reference now to, a controllerhoused in user interface(see) includes a microprocessor, user start switch, blower terminals, power source, temperature sensor terminals, indicator lightsand wireless transmission module. The controller is an automation device that processes sensor signals, manages electrical flows and executes the program for operating the cookstove and auxiliary components. The controller manages the speed of the blowers and the ratio of the speeds of the two blowers to optimize combustion. The controller microprocessor may be a Programmable Logic Controller (PLC), microcontroller-based bespoke controller such as an STM32 with a custom PCBA, off the shelf computer or any suitable programmable controller that can communicate with power electronics, motor controllers, variable frequency drives, PWM modules and any necessary electronic components via digital and analog communication protocols. The controller also may include a wireless data transmission module and indicator lights to provide information to the user as well as the distributor, manufacturer, carbon credit entity or any party that may find value in stove data reports such as a marketing team. The wireless data transmission module also supports firmware updates. The controller includes a power source which may be a battery, thermoelectric element, and/or connection to shore power or any suitable electrical power source compatible with the microcontroller. The controller includes firmware that operates the cookstove and generates the sensor data report that may be converted to carbon credits. A K-type thermocouple with high temperature insulation able to withstand the surface temperatures of the mounting surface would be suitable for use as the temperature sensor.

Operating under the protocol managed by the controller, the biomass cookstove facilitates roughly three distinct thermochemical phenomena: pyrolysis, reduction and combustion. Pyrolysis is the heating of a material in absence of oxygen, this thermally breaks molecular bonds creating smaller molecules often in vapor form. Smoke is a typical aerosolized product of pyrolysis familiar to most people. Combustion is the heating of a material in the presence of oxygen resulting in an exothermic reaction of molecules generating primarily COand HO. In the typical wood fire, wood is being pyrolyzed by the combustion occurring around it. Because the wood is engulfed in flames, oxygen is scarce at the material surface, but heat is being transmitted, driving pyrolysis. When one watches wood burn, one is typically watching the pyrolysis gases (smoke) combusting, not the solid material. This changes in the char phase of a wood fire in which the solid carbon of the char is combusting with oxygen according to the following reaction O+C+heat→CO. In the case of a hot coal bed, the combustion products of carbon, COreacts with the hot carbon in a reduction reaction that generates 2CO according to this reaction CO+C+Heat→2CO. A blue flame on the surface of the coal bed is due to the CO combusting with oxygen after being created by reduction according to the following reaction 2CO+O+Heat→2CO+more Heat. During the Fresh Fuel Phase, a small amount of primary airis used to combust fuel and generate heat to drive pyrolysis of the fresh fuel, then secondary airis used to combust the pyrolysis gases. The amount of air needed to generate the pyrolysis gas is relatively small compared to how much air is needed to fully combust the pyrolysis gas, so fixed ratio TLUD stoves will have more secondary air holesthan primary air holeswith a shared forced air source. During the Char Phase, each oxygen atom required to generate combustible gas needs to be matched with two oxygen atoms to combust them. Combining the reactions together and balanced O+C+heat→CO+C+Heat→2CO+O+Heat→2CO. To support the secondary air requirements of the wood gas phase, the secondary air holesof combustion cupare located above the primary air holesas seen in. Because it requires one Omolecule to generate the gas and one Omolecule to combust the gas, the primary air blowermust run at a rate calculated to supply sufficient combustible gas in the proper proportion for combustion throughout the fresh fuel, transition and char phases. Consequently, there must be a method to change the blower speeds to match the combustion phase. This is accomplished by monitoring the temperature of the combustion cup base of the combustion cupusing the lower temperature sensor. Since the fuel burns from the top to the bottom, the primary (lower) temperature sensor will not read a high temperature until the flame front in the primary combustion zone is near the base of the combustion cup and the fuel in the base of the combustion cup is also very hot. The fuel is very hot because it has undergone pyrolysis and will be in the char phase when the lower temperature sensor detects a certain temperature or rate of temperature change of the combustion cup base, referred to herein as the CHARLIP temperature. This trigger temperature or rate varies based on how much fuel was put into the combustion cup in the beginning. The control system will vary the trigger temperature or trigger temperature change rate, or trigger temperature change second derivative (the rate of change of the rate of change) depending on how long it takes for the primary temperature sensor to achieve the CHARFLIP temperature. Trigger temperatures and signal temperatures will vary between stoves and fuel types and so anyone skilled in the art will be capable of extracting these values through testing.

With reference now to, the cookstove receives biomass as a fuel and is managed by the control systemwhich generates sensor data reports and loads them on to a database. Sensor data reports can be queried from the database to a carbon credit registryor any destination that will yield accredited carbon credits. A power sourceconnects electrically to the controller. The controller may comprise a charge controller circuit and charging port, such as a USB-C port or any suitable electrical receptacle or plug. The microprocessoris electrically connected to the top temperature sensor, lower temperature sensor, primary air blower, secondary air blower, battery, transceiver, speed sensorand, memoryand firmware, and mechanically connects to the adjustment dialand user interface. The speed sensors may be integrated into the blowers to detect blower RPMs, or measure air speed in the primary and secondary airflow paths.

As seen inand discussed more fully below, when the user turns the stove on at, the controller will determine if the user has turned on the stove at. If it is determined that the cookstove has been turned on, the controller will operate the stove according to the cooking protocol, at, and upon completion will either shut off the cookstove automatically or the stove will be manually shut off, at. During stove operation sensor data is recorded in memory. If it's time to send a data report, at, then the report is sent to a database, at. It then checks to make sure that the data was received correctly, at, using an appropriate protocol, at. After confirming the data was received correctly, the memory is cleared, at, to make sure the onboard memory does not fill up. The report timeframe should be less than it would take for heavy use of the stove to fill up data by some safety factor.

are a more detailed flow diagram of the software executed by the control system with an emphasis on the stove cooking protocol in. The program begins when the user starts the stove at. Then the temperature sensors are read to detect whether the stove has been recently operated and is “hot”, or if it is “cold,” at. If the stove is hot, the Hot Startup Protocol is executed, at; if it is cold, the Cold Startup Protocol is executed, at. After the startup protocol is executed, the temperature sensors are queried to determine if the stove was successfully lit and there is a stable, hot flame, or if the flame extinguished and the stove needs to be relit, at. If the ignition is successful, the fresh fuel phase protocol is executed, at, to burn the fresh fuel optimally. During the fresh fuel phase, the temperature sensors are queried, at, to detect if the fresh fuel has burned to charcoal. When the base of the combustion cup reaches a specified temperature or rate of change of temperature, at, the transition phase protocol is executed, at, to optimize emissions and flame stability while the last bit of fresh fuel is converted to charcoal. When the base of the combustion cup reaches a specified temperature or rate of change of temperature, at, the char phase protocol is executed, at, to optimize emissions and efficiency. When the upper temperature sensor temperature drops, at,, the flame is extinguished, and the stove shuts down, at. During operation, the sensor data of blower RPM and temperature is recorded to accurately determine the amount of fuel being consumed and whether or not the stove was successfully as indicated by operating indicator lightsand wireless transmission module.

As seen in, the pot standrests on the top lid. The wind guardis supported by the top lidas well but may also be supported by the pot stand. The pot stand is manufactured from a suitable material and finish to withstand direct contact with flames while supporting the weight of a pot full of water. Steel with a high temperature coating, stainless steel or any suitable material may be employed. The pot stand also disrupts the flow of combustion gases. The pot standrests on the top lid. The wind guardis supported by the top lidas well but may also be supported by the pot stand. The pot stand should be designed to absorb minimum heat from the flame and cookware to prevent a reduction in thermal efficiency. The wind guardprevents external airflows such as wind or circulation fans from blowing out the secondary combustion or reducing thermal efficiency by blowing the hot gases away from the cookware. The housingis a structural component that supports the top lidand transfers the cookware weight to the skid plate. The skid plate transfers the weight of the cookware and stove to the supporting surface such as a table or the ground. The housing also supports the user interface. The lift handleis used to lift the cookstove. Skid plate cooling air holesallow air to enter the assembly to cool the enclosure while also preventing pests and debris from entering the enclosure. The user interfaceattaches to the housing and supports controllerand should be designed to absorb minimum heat from the flame and cookware to prevent a reduction in thermal efficiency. The adjustment dialis mechanically connected to the controller and supported by the user interface. The adjustment dialand user start switchmay be separate components or a combined component such as a potentiometer or rotary encoder with a switch feature integrated for the user to establish a target flame level, e.g., the volume of the flame. The wind guardprevents external airflows such as wind or circulation fans from blowing out the secondary combustion or reducing thermal efficiency by blowing the hot gases away from the cookware. The lift handle socketprovides a mounting point for the lift handle and serves as a hinge so that the lift handle may be set lower to not obstruct the space around the cookstove. The batterymay be attached to housing, air plenum(see) or skid plate. In one embodiment, the battery may be held by a sheet metal piece spot welded to the housing for simplicity of assembly.

Referring now to, air plenum assemblyis attached to the air jacketwith means to prevent primary or secondary air from leaking through the joint. This may be achieved through a combination of a gasket, an adhesive suitable for the local temperatures, a precision metal-to-metal fit or any suitable method familiar to those skilled in the art. The air jacketcan withstand the radiant heat from the combustion cupand air separatorover a long period of time. Most stainless-steel alloys are appropriate for this application. The air separatorwith the combustion cupforms a gap G, creating a path for the primary air flow. The air jacketsupports the combustion cup. The top temperature sensoris received in a small aperturein the air jacketto secure it immediately adjacent to the combustion ring yet protected from heat eddies allowing it to be reliably heated by the radiant heat from the combustion cup but also not to interfere with the reinstallation of the combustion cup. The interface between the combustion cupand air jacketshould be relatively free of air leaks. The air separatoris a sheet metal assembly that can withstand the radiant heat from the combustion cupover a long period of time. Most stainless-steel alloys are appropriate for this application. The air separatorencloses the primary air flow, preheats the primary air before combustion, and locates the combustion cup. The interface gapbetween the top flange of the air separatorand combustion cupoutside diameter and cross-sectional area must be sufficient to allow easy removal and reinstallation of the combustion cupbut also allow for differentiation between the primary and secondary air flows,. If the gap is too large, the primary and secondary air flows will not be differentiated, and the stove will operate much like a single blower TLUD. The correct gap can be determined for any stove geometry by computation of fluid dynamics simulation and empirical testing. The air separatoralso supports the primary temperature sensor. The perforated plate supporting primary temperature sensoralso serves as a radiant heat barrier to prevent conduction of heat to the air plenum assemblyand therefore the primary and secondary blowers,. The diffuseris a removable component that directs the gases to the wall of the combustion cup for optimal mixing with the secondary air flow. In the illustrated embodiment the diffuseris supported by an annular shelf(see) of the combustion cup. The diffuser features a handlethat allows a tool to be used to remove it when it is hot. The diffuserand combustion cupface particularly high temperatures, combustion gases, pyrolysis gases, producer gas (CO and H2—reducing agents) and oxygen, so must be constructed of a refractory material such as ceramics, Inconel®, SS310, SS326 or any suitable alloy capable of long-term exposure to combustion temperatures and gases in presence of oxygen. Insulationserves to slow migration of heat from the combustion assembly into the housing and electronic components. The Insulation must be of sufficient thickness to keep the electronics below their rated operating temperature even during hot days, next to a source of heat or in direct sunlight. The insulation should also be stable when subjected to the surface temperature of the air jacket. Suitable materials are ceramic wool, fiberglass or any insulative material that will not degrade, pyrolyze or combust when exposed to the temperature of the air jacket. The upper temperature sensorand bottom temperature sensorare positioned such that airflow does not impact the readings substantially. If improperly placed, the temperature readings will be changed by airflows and aggravate the performance of the control system. Upper temperature sensoris placed between the neck of the air jacketand combustion cupsuch that airflow does not cool the sensor. Similarly, primary temperature sensoris located in the center of the air separator which features a scalloped plate that directs airflow near the air separator wall and directly into the primary air holes. This creates a dead space where airflow is minimal at the location of primary temperature sensor.

As seen in, diffuserincludes a central domesurrounded by an annular peripheral liphaving openingsthrough which hot gases flow from the combustion cup. The diffuser includes an upturned tapered peripheral flangeto facilitate insertion of the diffuser in the combustion cup as shown. Tapered peripheral flangealso provides structural rigidity to prevent warping under thermal stresses and cycles. Central dome, peripheral lip, peripheral flangeand the walls of the combustion cupform an annular flame wellinto which the combustible gases flowing up from the combustion cupare directed close to the secondary air holesfor more effective mixing of the primary and secondary gas flows. The combustion cuphas an annular shelfwhich supports the diffuser. The diffuser handleand combustion cup cleatcan be used to remove the diffuseror combustion cupusing a tool during operation. The combustion cup has two rows of staggered holes for flow dynamics that are favorable to clean combustion. These holes may be of different diameters to optimize fluid dynamics for best mixing.

Referring now to, it is seen that the combustion cup is tapered to make removal and installation much easier as shown by comparing datum line A with the wall of the combustion cup. As seen, the combustion cupis closely nested inside the air separator. During operation of the stove, the combustion cupheats to a high temperature and swells in diameter thereby reducing the radial width of the interface gap G formed between the combustion cupand the air separator. As discussed above, it is important that the interface gap G must be of a sufficient diameter and cross-sectional area to allow differentiation between the primary and secondary air flows. The combustion cupis therefore tapered to prevent it from binding during removal.

As seen in, primary air plenumis attached to the air plenum top platesuch that primary plenum air passagesare sufficiently isolated from secondary plenum air passage slotsthereby sufficiently isolating primary air flow passagefrom secondary air flow passage. The air plenum bowlis attached to the air plenum top platethereby encapsulating the primary air plenum. The nested plenums provide a few benefits; one is using space efficiently and the other is providing heat barriers from the combustion cup to keep the skid plate cool. Radiant heat will warm up the primary air sub plenum and primary and secondary air flowing around the sheet metal will actively cool the components such that any parts of the stove that the user may contact does not get too hot to touch.

The various embodiments of these concepts and methods are thermally efficient, effective for cooking and heating, user friendly, and able to generate reports for carbon credits, greatly increasing the relevance for clean cooking with sustainable biomass around the world. In short, a system and method have been disclosed for providing a significantly better clean cooking solution that combines the low cost of traditional fuels with the clean burning high performance of fossil fuels while using locally produced renewable feedstocks.

An automated two-blower biomass cooking stove according to the invention is a solution for combustion of solid fuels that is optimized for ease of use, low emissions, efficiency and usage reporting. Operating the stove starts with filling the combustion cup with fresh fuel and inserting the combustion cup into the combustion assembly. Then the user will start the stove using the user interface and light it making use of any variety of suitable methods likely based upon available accelerants. The preferred method is using about 30 mL of ethanol and lighting it with a match. From there the accelerant will burn, heating up the upper thermocouple. When the upper thermocouple triggers the control system to start the startup protocol the stove will either enter a cold or hot startup protocol depending on the temperature of the upper thermocouple. During the hot or cold startup protocol the blowers are set at a few speeds, starting relatively slow to prevent blowing out the Initial flame, then escalate to accelerate startup and keep emissions low and startup time short. After the upper thermocouple heats up enough, the control system will change the blower speeds to whatever the user has set the heat setting to. The control system will maintain these blower speeds until the user changes the heat setting or the transition phase protocol initiates. During the transition phase, the blower settings are such that the secondary air is relatively high compared to the fresh fuel settings and the primary air lower. This is because the rate of gas production increases relative to the primary air since the bottom of the combustion cup will get very hot and transfer heat to the fuel around the bottom of the cup. After the transition phase, the stove will enter the char phase where the blower speeds are optimized for clean combustion of charcoal. After the flame at the top extinguishes, the upper thermocouple will decrease in temperature and the control system will turn the blowers off and execute a shutdown protocol. The user may then remove the combustion cup and dump out the remaining ash and charcoal and start the process over again.

The innovation disclosed herein is based on the systematic application of the knowledge generated from decades of biomass stove research, combined with our team's expertise in biomass gasification system design and engineering. The intended result is a prototype small-scale biomass gasifier stove that will overcome the limitations of existing state-of-the-art stoves by meeting specific requirements:

This can be achieved through implementing simple computer-controlled air management using temperature sensors and multiple fans to dynamically adjust combustion conditions.

While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility.