The present invention relates to a device and a method for combustion of combustible ma terial in a pyrolytic chamber, wherein the combustion can be continuous. It further relates to a method for continuous production of heat.

BACKGROUND

Around 3 billion people around the world are dependent on traditional cooking stoves and 2 billion tons of biomass are burned each year. Exposure to air pollution is typically up to 100 times more than recommended as healthy by WHO. For some of these people, up to 40% of the income for the household is spent on fuel and up to 5 hours each day are spent on collecting fuel.

Wood or other biomass are put into stoves, flames ignited and burn directly (direct burning of solid fuels) producing flames used for cooking with ash as final -byproduct or residue left. The design of these could start from just 3 stones on which a pot is put, then cylinders with pot stands and main inlet for biomass, mainly wood, and sometimes with heat insulation around the cylinder. Gradually cookstoves have been improved with special air inlets and special forms all to achieve energy efficiency and reduce smoke.

Biochar cookstoves (also classified as pyrolytic cookstoves or biomass gasifier cookstoves) operate under a thermochemical process called pyrolysis or pyrolytic combustion. Pyrolysis is the burning of biomass (wood, waste...other biomass forms) in the absence of, or very limited, oxygen conditions which results in simply extracting a mixture of different gas mol ecules within the biomass and only these gas mixtures are directly burnt at high oxygen conditions compared to the systems above in which solid fuels were directly burnt. During pyrolysis, since only gases with less carbon content are direly burnt, the solid content left has a higher organic carbon content and is called biochar.

Pyrolytic combustion, or pyrolysis, heats biomass in an environment with limited oxygen conditions. The technique has been used in thousands of years, mainly in the industries. The pyrolytic combustion produces pyrolytic gases, volatile substances from the fuel that takes fire and will be combusted to produce heat until all volatile substances have been com busted. At last also the solid residue will be combusted. The residue from the pyrolytic com bustion in cooking fires using biomass is biochar. The biochar can in turn be used in different ways. In pyrolytic combustion, it is possible to use fuels that are less favorable in traditional com bustion. For example, biomass having a lower energy content, such as straw, reed and dung can be used in pyrolytic combustion. This is because it is the gas that is incinerated, and problems related to combustion of solid fuels, such as emission of toxic substances and particles can thus be avoided. There are several problems with the existing biochar cookstoves. One problem is that the cookstoves operates in batches, meaning that when the chamber is out of fuel it is not pos sible to cook anymore until the ashes have been removed, new fuel inserted, and combus tion starts again. Both the input of biomass and removal of biochar can only be done as discontinuous for these cases. This takes time and the stove, and the pots used for cooking or boiling water, will be cold before the cookstove can be used again. This requires extra energy every time the stove is restarted. Another problem is that existing cookstoves work ing with pyrolysis demand a preconditioned or pretreated biomass such that moisture con tent fall within 8 to 20%. This is necessary to achieve pyrolysis and not only combustion. If the moisture content falls outside this range problems such as lots of smoke and huge pres- ence of carbon monoxides in smoke occurs when the fuel is ignited.

A further example of a problem is that most of the existing biomass cookstoves are not energy efficient, they only supply energy to specific and small needs and sometimes could not even boil water before one batch of feedstock is finished. They are commonly con structed with two concentric cylindrical containers, where the inner cylinder is the fuel pot. The fuel pot is provided with holes in the base, which serves as the primary air inlet. The fuel pot is also provided with holes on the neck, serving as a secondary air inlet. The outer cylinder is provided with holes near the bottom on the sides. During combustion, air enters these holes, either by natural air draft or forced with a DC fan depending on requirement and construction model. The user fills the fuel pot with fuel, just below the secondary air inlet holes and ignites the top layer of fuel for the pyrolysis to start. Air then flows in through the primary and secondary air inlets. The primary inlet helps the draft of pyrolyzed wood gas flow upwards. This is called a top-lit updraft gasifier. Cooking furnaces like this have for example been described in CN 103742946, CM 101021336, CN 104006413, CM 204329066 and CN 107238109.

WO 2017/202853 describes a pyrolytic burner of conventional batch type. The chamber is a vertical chamber, which means that it further requires a ventilation apparatus connected in the bottom of the chamber to drive the reaction. The ventilation apparatus requires en ergy to be used, which will give a system that is not energy efficient. The present invention solves the above-mentioned problems by providing a cookstove that can be used continuously and therefore also is more energy efficient. The cookstove pre sented can be used as a part of a system as a strategy for sustainable emission reduction

Hence, the invention relates to a device for combustion of a combustible material, which device comprises at least one inner wall and at least one outer wall, creating a double wall space in between, which double wall space is provided with at least one primary air inlet, and a top wall having at least one top opening. The device further comprises an inclined tubular means; which tubular means further comprises an inlet for the combustible mate rial in the upper part, a pyrolytic chamber located on the inside of the inner wall of the tubular means, an outlet in the lower part of the inclined tubular means, and an outlet cover. The double wall space comprises a secondary air distribution zone for distribution of hot air and facilitating mixing of pyrolytic gases which leads into a combustion zone and further to a flame zone

The tubular means is preferably inclined with an angle of 30 ± 15 degrees from a horizon tal line. The device can further be provided with a thermocouple zone comprising at least one thermoelectric generator to convert heat into electrical power. The outer wall can further be provided with a heat insulator. The device is preferably provided with a stand, which stand can further comprise an elec tric charging control unit and at least one electric charging outlet port.

The invention further relates to a method for using biological material wherein biological material is combusted in the device and biochar is thereafter collected. The biological ma- terial is preferably a biomass.

The method can further comprise one or more of the following steps:

Use of energy from the combustion for cooking food in a pot placed in the pot holder;

Producing electricity by utilizing at least one thermoelectric generator;

- Using the biochar for water filtering and/or processing the biochar. This biochar can further be used as a fertilizer in soil.

The method is preferably a continuous method for production of heat.

In the following, the invention will be described in detail, with reference to exemplifying embodiments of the invention and to the enclosed drawings, in which: Fig. 1A shows a perspective view of an outer shell of one embodiment of a device for pyro lytic combustion of biomass

Fig. IB shows a vertical cross-sectional view of an upper part of the device

Fig. 2 shows a view of one of the short sides of the device for pyrolytic combustion of bio mass

Fig. 3 shows a view of the other short side of the device for pyrolytic combustion of biomass Fig. 4A shows a cross sectional side view of a device for pyrolytic combustion of biomass Fig. 5 shows a block chart of a method for using a biological material

Fig. 6 shows a block chart of a life cycle achieved by using the device in the method

Referring to Figs. 1-4 a device according to the present invention suitably comprises at least one inner wall and at least one outer wall, creating a double wall space in between, which double wall space is provided with at least one primary air inlet. It further comprises a top wall having at least one top opening, an inclined tubular means; which tubular means fur- ther comprises an inlet for the combustible material in the upper part of the inclined tubular means, an inlet cover, a pyrolytic chamber located on the inside of the inner wall 3 of the tubular means for combustion of biological material, an outlet in the lower part of the in clined tubular means and an outlet cover. The double wall space comprises a secondary air distribution zone for distribution of hot air and facilitating mixing of pyrolytic gases, leading into a combustion zone and then continues to a flame zone adjacent to the top opening. At least one of the inner walls comprises through holes (opening) to let hot air flow into the secondary air distribution zone.

Fig. 1A shows a first embodiment of the device for pyrolytic combustion of a combustible material, preferably biomass, wherein the device 1 comprises an inclined tubular means 2, which device 1 is provided with inner walls 3, outer walls 4, which has a tubular outer wall 4A and planar outer walls 4B, and a top wall 17. The device 1 can further be provided with a stand 16. The inner wall 3 and the outer wall 4 create a double wall space 15 arranged between said inner wall 3 and outer wall 4. The double wall space 15 follows the shape of the substantially circular inclined tubular means 2 in the lower part of the device and thereafter forms a space above a pyrolytic chamber 6 comprising a secondary air distribu tion zone 9, having through holes as openings 13, between the inner wall 3 and the outer wall 4, leading toa combustion zone 11. The hot air coming out of the openings 13 meets the pyrolytic gases and are burned in a flame zone 12. These are described more in detail with reference to figure 4. The inclined tubular means 2 is preferably an essentially circular tubular means but could also be a rectangular tubular means.

The double wall space is provided with at least one primary air inlet 8 on one of the short sides of the tubular means 2, where air at ambient temperature enters the device. The at least one primary air inlet 8 is preferably provided in the lower end of the inclined tubular means 2 and has an elongated shape to more effectively let air into the double wall space. In the embodiment shown in figure 1A, six elongated inlets 8 are provided. It is however possible to have either more or fewer inlets. The number of inlets is preferably adapted to the size of the tubular means 2. The tubular means 2 further comprises an inlet 5, in one end of the device. The inlet 5 is provided with a cover 51, which can be opened for insertion of fuel, i.e. a combustible ma terial, in the upper part of the inclined tubular means. The inlet 5 is preferably provided on the short side in the upper part of the tubular means 2. After insertion of the combustible material, the inlet 5 is closed so that no air enters the chamber through the inlet to let the pyrolytic combustion take place. The inlet will only be opened later in the process to add more fuel, if necessary. The inlet 5 can also be used to control the flame, hence heat with little effect to quality of biochar within this scale of production.

Combustible material can for example be pellets, wood, sawdust or wood dust (a byproduct or waste from woodworking), rice straw (agricultural byproduct consisting of the dry stalks of rice crop, after the grain has been removed), dry dung (animal waste that has been dried in order to be used as a fuel source), biomass briquettes (a biofuel substitute mostly made of green waste and other organic materials), or any other fuel suitable for use in a pyrolytic chamber. In this description, the combustible material will be called "biomass", but the per- son skilled in the art understands that also other types of combustible material can be used in the device 1.

A pyrolytic chamber 6, for combustion of the biomass, is located inside of the inner wall 3 of the tubular means. The pyrolytic chamber will be described more in detail with refer ence to Figs. IB and 4. In an end opposite to the inlet 5 there is an outlet 7, where the byproduct can be re moved. The outlet is preferably provided in the lower part of the inclined tubular means together with the at least one primary air inlet. The location of the outlet in the lower end of the inclined tubular means facilitates removal of the byproduct more easily. It could also be possible to remove byproduct from an outlet provided on the side of the pyrolytic chamber (not shown). The outlet 7 is provided with an outlet cover 71, which can be opened for discharge or removal of the byproduct from the chamber 6. In this embodi ment the cover 71 is an outlet disc but can be any type of cover that can be opened and closed and that prevents air from coming into the chamber when it is in a closed position. The cover 71 is preferably provided with a handle 72. This is described in more detail with reference to Fig. 3 below.

The device is also provided with a top opening 10 above the flame zone 12. The top open ing 10 can in turn preferably be provided with at least one pot holder 14. The embodiment shown in figure 1A is provided with a pot holder comprising a plate 14' (not shown here) and three parts 14A, 14B and 14C, which three parts is provided to hold a pot, but also other types of pot holders can be used as is understood by a person skilled in the art, com prising more or lesser parts. It is also possible to provide the device 1 with more than one top opening 10 and more than one pot holder 14. The pot holder is provided for holding a pot for cooking food or boiling water.

The device 1 is further provided with a stand 16, which stand is further described with ref erence to fig. 4 below.

Fig. IB shows a vertical cross-sectional view of an upper part of the device 1, showing the tubular means 2, an inner wall 3, an outer wall 4, the pyrolytic chamber 6, the double wall space 15, the primary air inlet(s) 8, a top wall 17 having a top opening 10. A pot holder 14 is provided in the top opening 10. The pot holder comprises a crucible plate 14' and three parts, 14A-C, for holding the pot. The crucible plate 14' is provided below the three parts 14A-C, inside the device 1. The crucible plate 14' can collect any black carbon that falls down. The black carbon can also fall back directly into the biochar or pyrolytic zone. The crucible plate 14' preferably has a bowl shape, but also other shapes can be used. The pot holder 14 is preferably removable.

The inner wall 3 comprises a tubular inner wall 3A and a planar upper inner wall 3B. The planar upper inner wall 3B comprises openings 13 to the secondary air distribution zone.

The secondary air distribution zone 9 brings hot air from the pyrolytic chamber 6 through the openings 13 and into a combustion zone 11. The gases inside the pyrolytic chamber are combusted when they meet the hot air coming through the openings 13 in the double wall. The resulting exhaust moves towards the flame zone 12 and the top opening 10 to release its energy. This is described in more detail below with reference to Fig.4. The pyrolytic chamber 6 is inclined by approx. 30 degrees from a horizontal plane. The in clination can be varied within ± 15 degrees but has shown best effect for pyrolytic combus tion with an inclination of 30 ±9 degrees. The circular tubular shape of the pyrolytic chamber has proven most effective for the pyrolytic combustion of the material to take place. It is possible to increase the length of the chamber 6 (and the rest of the device 1) to add more top openings 10 and/or pot holders 14 to the top of device 1. The space of the pyrolytic chamber is defined by the inner walls 3A and 3B, the inlet 5, the outlet 7 and the top wall 17. In the lower part the inner wall is curved (3A) and in the upper part it is in an upright planar position (3B). The top wall 17 of the device 1 is provided with a top opening 10 to which the pot holder 14 can be attached, and a pot placed for example for cooking food or heating water.

The inclination of the pyrolytic chamber makes it possible to achieve a continuous opera tion, but it also contributes to achieve a turbulent flow, as described further below.

Fig. 2 shows one short side of the device 2, comprising an inlet 5, which inlet is provided with a cover 51. In this embodiment the cover 51 is a rotatable inlet disc but can be any type of opening that can be opened to let biomass in and the closed to prevent air from entering the pyrolytic chamber 6. The cover 51 is preferably provided with a handle 52. The handle can be any handle that can be used to open the cover 51 but is preferably of a ma terial that will not be too warm when the device is in use. In the case where the cover 51 is an inlet disc, the handle will be used to rotate the disc into a position where an opening appears in the outer wall. The inlet disc can be rotated by pushing the handle 52 so that there is an opening in the outer wall 4 and fuel, biomass, can be fed into the chamber 6. After the material has been inserted, the inlet disc is rotated in the reversed direction so that the inlet is closed, and no air can enter the chamber.

Fig. 3 shows the other short side of the device 2, comprising an outlet 7, which outlet is provided with a cover 71. In this embodiment the cover 71 is an outlet disc 71 and is pro vided with a handle 72. The handle can be any handle that can be used to open the cover 71 but is preferably of a material that will not be too warm when the device is in use. In the case where the cover 71 is an outlet disc, the handle will be used to rotate the disc into a position where an opening appears in the outer wall. The outlet disc 71 can be rotated by pushing the handle 72 so that there is an opening in the wall 4. When the outlet is open, the byproduct from the pyrolysis can be removed through the outlet 7 and the cover, or outlet disc, is then closed again. The outer wall 4A of the short side of the device 1 shown in Fig. 3 is also provided with primary air inlets 8, as described above.

Figure 4 shows a cross-sectional side view of the device 1, showing the inclined pyrolytic chamber 6 provided with an inlet 5 and an outlet 7. Above the pyrolytic chamber, three different zones are located; a secondary air distribution zone 9, having through holes 13, between the inner wall 3 and the outer wall 4, a combustion zone 11 and a flame zone 12. Figure 4 shows one half of the device 1, meaning that the other half of the device 1 is pref erably also provided with the same three zones. The secondary air distribution zone 9 brings hot air from the chamber through the openings 13, which openings are an array of through holes, and into a combustion zone 11. The through holes 13 are provided on at least one inner wall 3, more preferably on two opposing inner walls along the length of the tubular means 2. The through holes 13 are preferably provided in an inclination to a horizontal plane. The inclined array of through holes 13 leads to a turbulent flow of hot air which fa cilitates the mixing of pyrolytic gases at the combustion zone. The inclination of these holes 13 are preferably parallel to the combustion chamber 6 and it is possible to vary the angles by 30 +/- 15 degrees to a horizontal plane. The array of through holes can also be provided in a zig-zag form.

In the combustion zone 11, the pyrolytic gases and the hot air from the double wall space will be mixed by turbulence that is created by the inclined arrangement of the holes and the pressure difference it creates. The resulting exhaust moves towards the flame zone 12 and the top opening 10 to release its energy.the flame zone 12, which is close to the top opening and the pot holder, and will provide the heat needed to cook food or heat needed inside a boiler.

The flame zone 12, is provided adjacent to the top opening 10. In the flame zone 12, the pyrolytic gases will be burned completely or optimally due to the presence of a high amount of oxygen molecules at the surroundings of the turbulent flow of initially ignited gases from the combustion zone. It is important to note that the flames are initially generated when starting the system by firing a quantity of biomass. The same flames are improved thereaf ter to firing gases which moves towards a region with high and expandable oxygen mole cules in concept. This is observed as flame zone by user. The resulting exhaust gases are not homogenous (i.e. not the same kind), they are com posed of mixture of largely combustible gases (such as methane (CH4), carbon monoxide (CO) and hydrogen (H2)) which will burn completely in presence of the hot air from double wall space. In addition to these gases there is also some hydrocarbons and some incomplete by-products of pyrolysis present, which are Volatile Organic components (VOCs). Because of the heavy nature of these VOCs, they will not burn completely at the first contact be tween gas mixture and hot air. They will move a little further (some will give other gases like CO and H2 when break down), enlarging the combustion zone (though decrease the kinetics of combustion). The rest of the VOCs that is not transformed into gases are trans formed into black carbon (like in an internal combustion engine but very insignificant, hence the filtering of the exhaust). For this stove, the black carbon is retained at the crucible plate 14'. This crucible is as mentioned above, preferably bowl shaped and is in the beginning of the flame zone (where the flame from complete combustion and there is little or no pres ence of other pyrolytic gases). All the gases at this zone are expected to have been com busted with the hot air at probability greater than 90%. The crucible plate forms part of the pot holder or heat collecting device. The pot holder permits the blacked carbon to be washed away in case of any. It is also possible that the black carbon falls directly back into the biochar produced or pyrolytic zone. The black carbon is mainly carbon and do not alter the biochar quality. The rest of top plate 17 provides framework for heat recovery devices and flat easy cooking surface as other ovens. The device 1 can further be provided with a thermoelectric generator zone 18. A thermoe lectric generator produces a temperature-dependent voltage as a result of the thermoelectric effect, i.e. the temperature difference between the inside of the device and the air outside of the device can be converted into electric voltage due to the thermo electric effect The thermoelectric generator zone 18 preferably comprises a thermoelectric generator such as a Peltier element, (one example is TECl-127, but it could be any suitable generator) which converts the heat into electrical power of 4 to 12volts. Although the ther moelectric generator zone has been shown in this embodiment to be on a specific place of the device 1, the location of this can be varied.

Thermoelectrical generators are used to produce electrical power enough to power electri cal light bulbs of nominal wattages ranging from 5 to 25 watts at direct low voltages using the See beck-effect. The pyrolytic temperature of the stove ranges from B00°C up to a max imum of 500°C, such that some of the heat from the pyrolytic chamber is used to speed up the motion of air molecules in the combustion zone, making the temperature drop to an interval of 100°C to 200°C. A heat insulator, such as for example a ceramic insulator, mineral wool insulator, etc can be provided on the outer wall to reduce the heat of the surface to a range of 50°C to 65°C.

The device 1 is further preferably provided with a stand 16 (shown in Figs. 1A, 2, 3 and 4). Besides holding the device 1, the stand 16 can also be provided with an electric charging control unit 19 and at least one electric charging outlet port 20, such as for example USB- ports, for charging electrical equipment such as for example cell phones and light bulb con nectors. The electric charging control unit 19 can for example be electric power regulators in combination with storage batteries. This unit 19 regulates, stores and supplies the power at low voltages to the at least one charging outlet ports 20. The control unit 19 and the at least one outlet port 20 can also be placed located on other parts of the stand 16. The device is preferably provided with more than one outlet port 20. It is possible to have several dif ferent outlet ports, such as for example one or two USB-ports and one or two light bulb connectors. A person skilled in the art understands that the type of ports can be varied and that also other types of outlet ports can be provided.

In this way, it is possible to use some of the heat generated during the pyrolysis in the device 1 for charging electrical equipment.

The device 1 described are preferably used in a method for combustion of biomass. The method is further described below. To operate the device 1, the cover 51 is opened so that biomass can be inserted into the pyrolytic chamber 6 through the inlet 5. The cover 51 is then closed. Since the pyrolytic chamber is inclined, the inserted biomass moves downwards towards the outlet 6, which is initially closed. The outlet covers 71 is opened and a flame from for example a gas lighter or a match stick is used to ignite the biomass. As mentioned above, also other sources for ignition of biomass can be used. The cover 71 is then closed completely.

To ensure that the system lights up completely from the beginning, the cover 71 can be left open for about 1-2 minutes. It is also recommended to use easily flammable materials as the first charge of biomass inserted into the pyrolytic chamber to help overcome the acti- vation energy for pyrolysis.

To achieve pyrolytic combustion instead of normal combustion, pyrolytic conditions must be defined; i.e. burning in a controlled/limited amount of oxygen. To start the process, bio mass is first fed into through the inlet 5 to the pyrolytic chamber 6. The biomass is ignited, either manually or by any other means that can be used to ignite fuel. During the first part of the process, direct burning of the initial material will take place, which leads to energy and a small amount of ash. During this latent or lag phase of the process, it can be observed an instant small quantity of smoke which dies down within 1-2 minutes when pyrolysis grad ually takes over and stabilizes to produce pyrolytic combustible gases (mainly methane).

The combustion generates external energy into the pyrolytic chamber, this energy is neces- sary to start the pyrolytic process. The starting energy is then used to overcome energy barrier needed in intermediary processes (biomass drying, torrefaction, depolymerization) that usually occurs before pyrolysis. This is simply achieved by letting small quantity of bio mass first undergo normal combustion for a short while.

After this first combustion, where energy needed to overcome the energy barrier needed is created, pyrolytic combustion, or pyrolysis, takes place in the pyrolytic chamber. This pyro lytic combustion acquires enough energy to cause bond breaking and therefore atoms are free to mix and forms combustible gases. These combustible gases expand as continuously heated (as per Brownian motion), the direction of motion is towards a comburant attraction (oxygen) upwards to the secondary air distribution zone 9 and the combustion zone 11. The IB zones typically overlap each other, but each playing an interdependent role. The easier the removal and burning of these gases, the higher the efficiency of the pyrolysis in the cham ber. To achieve this, air at normal temperature is let into the double wall space through openings 8, that is linked to the pyrolytic chamber 6, following a temperature gradient. There is always air trapped in the double wall space 15. When pyrolysis is going on, the air in the double wall space 15 gets heated and must expand (Brownian motion). This air is then attracted towards the combustible gases. The inclined tubular means 2 contributes to achieve a turbulent flow. The gases produced in the pyrolytic chamber 6 rises towards the combustion zone 11 with a stronger affinity for an upward draft due to the presence of oxygen from the hot secondary air distribution zone 9. This air, once entered through pri mary air inlet 8, was trapped in the double wall space 15, between the inner wall 3 and the outer wall 4 and is constantly heated by the heat from the pyrolytic chamber. The heat increases the velocity of the air which forces air molecules to move faster compared to pri mary air. The higher the temperature of the pyrolytic chamber 6, the higher the speed of this hot air which creates a difference in pressure between the volume of air in the double wall space 15 and the air surrounding the device 1. This difference in air pressure forces cold air from outside into double wall space 15, through the at least one primary air inlet 8, creating the draft necessary for the combustion (the Bernoulli principle). The hot secondary air at high speed will then mix with the pyrolytic gases ignited by the initial flame which then expands more at the flame zone giving heat for cooking.

During this time, the possibility for air to flow directly into the pyrolytic chamber 6 is very low as the only way for air to enter the pyrolytic chamber is through the outlet 7 and the inlet 5. The inlet 5 is during the process commanded by the draft (affinity of some gases wanting to leave through this inlet to meet with oxygen) and since the pressure from inside is greater than air pressure from outside, the possibility of air going inside this is only when no heat inside, therefor limited. Since on the other side of the chamber 6, the outlet 7 is closed, then pyrolysis can be achieved.

The demand of energy is mainly based on the food being cooked. If cooking is going on, subsequent or series of biomass can be injected following the same feeding process de scribed above, but no relighting is needed which facilitates the continuous supply of heat. Fire accelerants can be used if found necessary, such as paper, starter cubes etc. to ignite the feed stock, especially of the feed stock is damp.

The flame, in the flame zone 12 can be adjusted by opening or closing the inlet and/or outlet discs. Opening of a disc will create a higher flame and closing of a disc will cause the flame to be lower.

The biochar produced, which is removed from the device 1 by opening the outlet cover 71, can be removed in series as well as accumulated and removed after cooking. Biochar re moved after cooking, when the device 1 is cooling down is more stable and has a higher quality as biochar. The biochar is preferably removed into any metallic vessel and quenched with cold water completely.

The device 1 and the process described above has shown to reduce smoke level with up to 85% as compared to traditional cookstoves. It is also easier to use because various biomass sources can be used as feedstock. Further, there is no need for blowing on the fire once started, which saves time.

The method according to the present invention, which is shown as a block chart in figure 5, therefore comprises at least the steps of

- combustion of biomass in a device 1 as described above; and

- collecting biochar from the device 1.

The energy, in form of heat, produced during the combustion can then be used for cook ing food, boiling water or the like. Some of the heat can also be used for producing elec tricity by utilizing at least one thermoelectric generator.

The byproduct, biochar can be removed from the chamber either after the combustion is finished and the system has cooled down, or it can be removed from the outlet 6 before cooling while the device is still in use. The safest way of removing the biochar is when the pyrolytic chamber is almost full of the byproduct. This is also more time saving than remov ing subsequently. However, it is also possible to remove biochar continuously by opening the outlet 7 and using a tool for displacement of the hot biochar out of the chamber 6. The biochar can then be placed in a container with water. However, biochar that is simply placed in a container with water affects the quality of biochar negatively because it does not lead to enough porosity of biochar. A better way of cooling the biochar is therefore to use water jets, either inside (in the case of removal at the end of cooking) or outside (if removal is done during use of the device) to cool down the biochar. Biochar of good quality can then be used further for filtering water or the biochar can be processed and used as a biochar fertilizer in soil. Biochar that is used for filtering water can in turn be used as biochar fertilizer in soil afterwards.

The provides a cookstove that can be used continuously loaded orfed with biomass material of different types and shapes obtained from diverse sources (farm residues like corn cobs and others, forest residues like tree leftovers and leaves, forest transformation wastes like sawdust, biomass briquettes and even dry components of municipal solid wastes). This therefore makes cooking and heating applications more easy, faster, reliable and energy efficient compared to the batch loaded systems which consume more time of users, not easy to handle as either dismantling before removal of by-products is required and or put- ting away pots or heat recovery vessels to add fuel in most cases . Most of the systems that have been used up till now are already limited to using specific types of biomass which could be wood, woodchips or pellets for their operation. This do not only limit them in fuel source but also encourage the unsustainable cutting of trees (deforestation) to fuel such systems.

The cookstove model presented in the present application can be used as a strategy for sustainable emission reduction whereby the farmers waste products " particularly from the agricultural sector which relates to major economic activity of the more than 2 billion peo ple using inefficient cookstoves" could have an added value of inputs in household energy for cooking and in return inputs in biofertilizers back to the farms permitting the right flow of energy and right recycling of nutrients on earth. The method according to the present invention gives an entire life cycle, as shown in Figure 6. Where leftovers from food can be used as fuel in pyrolytic combustion. The pyrolytic combustion in turn produces energy for cooking food, electricity for charging electrical equipment. The heat from the cookstove will also heat up the room where it is standing and dry biomass that is placed in that room. The byproduct, biochar, can be used for filtering water or processed to be a biochar fertilizer. The biochar fertilizer is placed in the soil to gether with seed to plant new seeds. Carbon dioxide in the air and the photosynthesis will provide new crops that in turn can be harvested and used for food. Where the leftovers can be used in the pyrolytic combustion. This model is then suitable as means for sustainable emission reduction as well as clean development mechanism accounting for direct emission reductions through smoke reduction compared to traditional inefficient systems and carbon storage. It also contributes to indirect emission reduction by increasing the capacity of growing more plants when biochar improves the soils, enhancing capture through photo synthesis. Above, an exemplifying preferred embodiment has been described. However, it is realized that the invention can be varied without departing from the basic idea of the invention.

Hence, the invention is not to be considered limited to the above described embodiments but may be varied within the scope of the enclosed claims.