WO2013190361A1

WO2013190361A1 - System and method for biogas and fertilizer production from household organic waste

Info

Publication number: WO2013190361A1
Application number: PCT/IB2013/001272
Authority: WO
Inventors: Yair TELLER; Erez LANTSER; Ronen MOSHE; Oshik Moshe EFRATI
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-06-20
Filing date: 2013-06-18
Publication date: 2013-12-27
Anticipated expiration: 2014-12-20

Description

SYSTEM AND METHOD FOR BIOGAS AND FERTILIZER PRODUCTION FROM HOUSEHOLD ORGANIC WASTE

BACKGROUND

Technical Field

[0001] Embodiments of the present invention relate generally to systems and methods for processing of household organic waste, particularly producing biogas and fertilizer therefrom.

Description of Related Art

[0002] Household organic waste makes up a considerable percentage of total waste. This waste is generally thrown out with the rest of the garbage, requiring transport and space in dumps. Such waste may also be used occasionally for purposes of producing compost, saving the transport and space requirements and producing a source of rich soil for the practiced user. However generally the production rates of such systems are limited by the size of material being input, and a number of further problems are often encountered including difficulty of operation, efficiency of the digestion process, low gas pressures, unsafe operation, and unpleasant odors.

[0003] Hence, an improved method for biogas and fertilizer production from such waste streams is still a long felt need.

BRIEF SUMMARY

[0004] According to an aspect of the present invention, a system and a method is provided for biogas and fertilizer production from household waste comprising an anaerobic digester adapted for production of fertilizer and biogas comprising: a container comprised of a set of panels and panel holders; at least one sink having a drain into which organic material is deposited; a grinder at the throat of said drain adapted to grind said organic material into a slurry; a flexible tank serving as an anaerobic digester in fluid communication with said drain adapted to receive said slurry and non-household organic material and to facilitate a population of anaerobic bacteria which decomposes said materials into a liquid part and a gaseous fraction; a pipe allowing disposing of the content of said flexible tank serving as an anaerobic digester; an overflow pipe; a flexible tank serving as a gas reservoir in fluid communication with said digester adapted to collect gas therefrom and store said gas; said gas tank is been pressured by at least one weight placed upon it; gas distribution means adapted to distribute said gas from said gas reservoir, wherein both biogas and fertilizer are produced and collected by an anaerobic digester.

[0005] It is within provision of the invention to further comprise at least one weight adapted to create pressure on said at least one flexible tank serving as a gas reservoir.

[0006] It is within provision of the invention wherein said at least one weight comprising a set of weights filled with the appropriate amount of material to create a predefined pressure.

[0007] It is within provision of the invention wherein said overflow pipe opening is located higher than the bottom of the flexible tank serving as a gas reservoir.

[0008] It is within provision of the invention to further comprise a plunger adapted to push or assist pushing of slurry into the digester tank, said plunger equipped with floats.

[0009] It is within provision of the invention to further comprise at least one non- household organic material (such as manure or animal dumping) intake sink.

[0010] It is within provision of the invention to further comprise at least one filter comprising at least one air pump and bacteria substrate.

[0011] According to an aspect of the present invention, a system and a method is provided for biogas and fertilizer production from household waste streams.

An in-sink grinder is used to grind household organic waste into a fine slurry that is fed into an anaerobic digester having substrates of large surface area adapted to facilitate the formation growth and maintenance of large colonies of anaerobic bacteria. These bacteria rapidly digest the organic input material into various fractions including a liquid fraction and a gaseous fraction. A key novelty of the gas collection chamber is its use of a novel open-bottomed reservoir which is held under water. As gas is directed into the reservoir water is displaced out of the open bottom of the reservoir, increasing the external water level and hence the pressure of the gas within the reservoir. This allows maintenance of the gas at a small positive pressure, allowing it to be conducted for large distances when needed, eliminating hazards of explosion and allowing for a unique pressure valve mechanism to be deployed setting an upper limit to gas pressure. [0012] It is within provision of the invention to provide an anaerobic digester adapted for production of fertilizer and biogas comprising:

a sink having a drain into which organic material is deposited;

a grinder at the throat of said drain adapted to grind said organic material into a slurry;

an anaerobic digester in fluid communication with said drain adapted to receive said slurry and to facilitate a population of anaerobic bacteria which decomposes said organic material into a liquid part and a gaseous fraction;

a liquid collection mechanism adapted to collect said fraction which comprises fertilizer;

a gas reservoir 120 in fluid communication with said digester adapted to collect gas therefrom and store said gas in an inner chamber 121, said inner chamber being surrounded by fluid and open on its bottom; gas distribution means 123 adapted to distribute said gas from said gas reservoir;

wherein both biogas and fertilizer are produced and collected by an anaerobic digester operating at high production rates.

[0013] It is further within provision of the invention wherein said fluid in said gas reservoir is water.

[0014] It is further within provision of the invention wherein said grinder is hand operated.

[0015] It is further within provision of the invention wherein said grinder is automated.

[0016] It is further within provision of the invention wherein said digester is provided with substrates having high surface area adapted to promulgate the formation of anaerobic bacteria colonies. [0017] It is further within provision of the invention wherein having fertilizer production rates of approximately 8 liters per day and gas production rates of approximately 1 m³ per day from a single-household waste stream.

[0018] It is further within provision of the invention wherein said gas reservoir is provided with a pressure gauge.

[0019] It is further within provision of the invention wherein said gas is used for purposes selected from the group consisting of: lighting; electricity generation; motive power; combustion; cooking; heat production; air heating; water heating.

[0020] It is within provision of the invention to provide a method for production of fertilizer and biogas comprising steps of:

providing a sink having a drain into which organic material is deposited;

grinding said organic material at the throat of said drain using a grinder adapted to grind said organic material into a slurry;

Digesting said slurry in an anaerobic digester in fluid communication with said drain adapted to receive said slurry and facilitate a population of anaerobic bacteria which decompose said organic material into a liquid part and a gaseous fraction;

collecting the liquid fraction of said digester, said liquid fraction comprising fertilizer;

collecting the gaseous fraction of said digester in a gas reservoir 120 in fluid communication with said digester adapted to collect gas therefrom and store said gas in an inner chamber 121, said inner chamber being surrounded by fluid and open on its bottom; distributing said gas using gas distribution means 123 adapted to distribute said gas from said gas reservoir;

[0021] It is further within provision of the invention wherein said gas reservoir is provided with a spillway for said fluid adapted to prevent said fluid from rising above a predetermined level. [0022] It is further within provision of the invention wherein said fluid in said gas reservoir is water.

[0023] It is further within provision of the invention wherein said grinder is hand operated.

[0024] It is further within provision of the invention wherein said grinder is automated.

[0025] It is further within provision of the invention wherein said digester is provided with substrates 207 having high surface area adapted to promulgate the formation of anaerobic bacteria colonies.

[0026] It is further within provision of the invention wherein having fertilizer production rates of approximately 8 liters per day and gas production rates of approximately 1 m³ per day from a single-household waste stream.

[0027] It is further within provision of the invention wherein said gas reservoir is provided with a pressure gauge.

[0028] It is further within provision of the invention wherein said gas is used for purposes selected from the group consisting of: lighting; electricity generation; motive power; combustion; cooking; heat production; air heating; water heating.

[0029] These, additional, and/or other aspects and/or advantages of the present invention are: set forth in the detailed description which follows; possibly inferable from the detailed description; and/or learnable by practice of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to understand the invention and to see how it may be implemented in practice, a plurality of embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

FIG. 1 illustrates an embodiment of the invention in side view;

FIG. 2 illustrates an embodiment of the system in isometric view;

FIG. 3 shows the sink, grinder, and drain of the system;

FIG. 4 shows an embodiment of the digester of the invention;

FIG. 5 illustrates another embodiment of the invention;

FIG. 6 portrays another embodiment of the invention; FIG. 7 illustrates a self-contained system of the invention;

FIG. 8 depicts the gas reservoir of the invention;

FIG. 9 illustrates a flow chart of the invention;

FIG. 10 illustrates a distribution system for gas of the system;

FIG. 11 illustrates an embodiment of the invention in side view;

FIG. 12 illustrates an embodiment of the sinks, grinder and intake pipe of the invention;

FIG. 13 illustrates an embodiment of the grinder of the invention;

FIG. 14 illustrates an embodiment of the grinder of the invention.

DETAILED DESCRIPTION

[0031] The following description is provided, alongside all chapters of the present invention, so as to enable any person skilled in the art to make use of said invention and sets forth the best modes contemplated by the inventor of carrying out this invention. Various modifications, however, will remain apparent to those skilled in the art, since the generic principles of the present invention have been defined specifically to provide a means and method for providing a system and method for biogas and fertilizer production.

[0032] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. However, those skilled in the art will understand that such embodiments may be practiced without these specific details. Furthermore just as every particular reference may embody particular methods, systems, yet not require such, ultimately such teaching is meant for all expressions notwithstanding the use of particular embodiments. Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention.

[0033] The term 'plurality' refers hereinafter to any positive integer (e.g, 1,5, or 10).

[0034] The invention is a combined composter and biogas generator based on anaerobic digestion of household organic waste. In Figs. 1-7 the main elements are seen. A sink 102 with faucet 101 is generally part of the system. The sink drain leads to a grinder 104 which may in some embodiments be hand operated with a crank 103 while in other embodiments the grinder may be electrically or otherwise automatically operated. The outlet of the grinder is conducted to a digester 130 designed to facilitate anaerobic decomposition of organic matter; this process has been found to have increased speed when the incoming material is ground as here. Substrates 107 are provided having large surface area and adapted to facilitate the formation growth and maintenance of large colonies of anaerobic bacteria which ultimately are responsible for the breakdown of organic material into various fractions including a liquid fraction and a gaseous fraction.

The gaseous fraction (largely methane gas) is conducted into a gas collection chamber 120 of the device. A key novelty of the gas collection chamber 120 (see for example Fig. 8a.) This chamber employs a novel open-bottomed reservoir 121 which is held under water or another liquid 125. As gas is directed through the gas inlet 110, water will be displaced out of the open bottom of the reservoir 121, increasing the water level and hence the pressure of the gas within the reservoir. As gas flows out of the reservoir (Fig. 8b) through an outlet 123, the pressure in the reservoir 121 decreases allowing water to enter from the bottom. This constitutes a felicitous solution to several problems. First, the gas is maintained under a small degree of positive pressure, allowing it to be conducted for large distances when needed (by opening a valve to the outlet 123). It has been found that even a few tens of torr are enough to provide flow through standard rubber or other tubing for tens of meters. Second, the hazards of explosion / fire are greatly reduced in such a system since the pressure is low and the vast majority of gas is physically surrounded by water. Third, the use of water allows for a unique pressure valve mechanism to be deployed; namely, if the water is allowed to reach only a certain height but no more (e.g by use of a spillway 801 or other means for the water, and/or a spillway or other means for the gas) then the gas pressure is maintained at a maximum pressure corresponding to the maximum water height and cannot rise above this value. Thus no matter how much gas is produced the gas pressure will never rise above a predetermined threshold.

[0035] Fig.2 shows an isometric X-ray view of the device. Here one may observe that the drain pipe 109 may be outfitted with a spiral screw 150 or other conveying and/or grinding means. By use of such a screw the organic matter may be forced under pressure into the holding vessel of the digester 130. The connection for gas outlet 110 (which allows gas out of the digester and into the gas reservoir) is seen as well.

[0036] Fig. 3 presents the device showing spigot 101, sink 102, grinder 104, and pipe 109.

[0037] Fig. 4 presents a closeup of the digester 130. Here the end of pipe 109 is shown revealing the use of a propeller 108 or other impelling means adapted to mix and churn the digestive broth as it ferments. Growth substrate 107 is shown as well and a baffle 160 intended to slow the sedimentation of undigested residues.

[0038] Fig. 5 presents another isometric X-ray view of the device. The digester 130 is visible as are the sink 102, pipe 109, gas reservoir outer chamber 120, the gas outlet 110 (which allows gas out of the digester and into the gas reservoir) is seen as well. An inlet 111 with valve is provided to allow the gas reservoir to be isolated from the digester if necessary.

[0039] The embodiment shown in Fig. 6 has the gas reservoir outer vessel containing both the inner vessel 121 as well as pipe 109. Thus the space 125 is entirely filled with liquid such as water.

[0040] Fig. 7 shows how the nutrient liquid is extracted after composting. An outlet 190 is provided allowing liquid to flow out of the digester and through a spigot 180 from which it may be collected e.g. in a bucket.

[0041] Fig. 9 presents a schematic flow chart of system operation. The first step is source separation; organic matter is sorted into dry and wet streams. The dry matter (paper, plastic, etc) is dealt with using conventional recycling means. The wet material is sent into the grinder which is usually located at the throat of a sink drain. After grinding the semi-liquid mixture of organic material and water is sent through piping (e.g. pipe 109, see Fig. 6 for example) to the anaerobic digester for breakdown. Without being limited by theory it is surmised that the extremely small particle size of material input to the digester, which has the consistency of a slurry, is responsible for the very high digestion rates attained by the system. The digester continuously outputs two products, namely a liquid fertilizer and a gaseous component. The liquid is used for fertilization e.g. of crops, household plants and the like, while the gas is used for cooking, hot water, and lighting, or the like. [0042] In Fig. 10 a simplified system diagram for gas use of the system is shown. Here a pump (which may be solar powered or otherwise) is use to pump gas through lines having pressure metering means to various end points such as gas cookers, stoves, generators, lights, and the like.

[0043] Some of the aspects of the device may be summarized as follows:

a. the device produces both organic fertilizer and biogas;

b. the device stores the biogas in an explosion-proof pressure-vessel of controlled maximum pressure;

c. the device produces fertilizer and biogas at accelerated rates due inter alia to the small particle size of material after grinding; d. the device is suitable for home use.

[0044] As mentioned above the gas collection chamber 120 (see for example Fig. 8a.) is provided with a number of novel elements. The open-bottomed reservoir 121 is held under water or other liquid 125. Gas enters through the gas inlet 110 after being produced by digesting or composting process occurring for example in container 130. The container 130 and gas inlet 110 are thus put into fluid communication for example by means of a pipe or the like, optionally with a valve to cut off fluid communication if need be. As gas enters the reservoir 121, water will be displaced out of the open bottom. Due to the increase of volume of water outside the reservoir, the water level will necessarily rise; the pressure of the gas within the reservoir will likewise rise as this process transpires.

[0045] The reservoir operates more or less in the fashion of a diving bell, an open- bottomed concave-down vessel capable of holding gas or other fluid. As gas is forced into the volume of the reservoir , water is forced out. Since the reservoir is contained within chamber 120, the water level in the chamber will rise as water is forced out of the reservoir 121.

[0046] Likewise, as gas flows out of the reservoir (Fig. 8b) for example through outlet 123, the pressure in the reservoir 121 will decrease (according to the well- known Boyle's law) allowing water to enter from the bottom. It has been found that a scant few cm of water head will suffice to force gas through piping for considerable distances, including for example all distances likely to be encountered in a residential setting.

[0047] As will be appreciated by one skilled in the art, this method of gas containment solves a number of problems simultaneously. First, the gas is maintained under a small degree of positive pressure, allowing it to be conducted for large distances when needed (by opening a valve to the outlet 123). It has been found that even a few tens of torr are enough to provide flow through standard rubber or plastic tubing for tens of meters.

[0048] For example for a flow rate of 10 liter/s, pipe length of 10m, and pipe inside diameter of 5mm, an initial pressure of 1 kg/cm², the pressure drop is calculated as 0.05kg/cm².

[0049] As will be appreciated by one skilled in the art the hazards of explosion / fire are greatly reduced in such a system since the pressure is low and the vast majority of gas is physically surrounded by water. Third, the use of water allows for a unique pressure valve mechanism to be deployed; namely, if the water is allowed to reach only a certain height but no more (e.g. by use of a spillway 801 or other means for the water, and/or a spillway or other means for the gas) then the gas pressure is maintained at a maximum pressure corresponding to the maximum water height and cannot rise above this value. Thus no matter how much gas is produced the gas pressure will never rise above a predetermined threshold.

[0050] In another embodiment of the invention the system 1000 comprising:

a container comprised of a set of panels and panel holders; at least one sink having a drain into which organic material is deposited;

a plunger adapted to push or assist pushing of slurry into the digester tank, said plunger equipped with floats;

at least one non-household organic material (such as manure or animal dumping) intake sink;

a grinder at the throat of said drain adapted to grind said organic material into a slurry; a flexible tank serving as an anaerobic digester in fluid communication with said drain adapted to receive said slurry and non-household organic material and to facilitate a population of anaerobic bacteria which decomposes said materials into a liquid part and a gaseous fraction;

a pipe allowing disposing of the content of said flexible tank serving as an anaerobic digester;

an overflow pipe;

a flexible tank serving as a gas reservoir in fluid communication with said digester adapted to collect gas therefrom and store said gas; said gas tank is been pressured by at least one weight placed upon it;

gas distribution means adapted to distribute said gas from said gas reservoir;

at least one filter comprising at least one air pump and bacteria substrate.

[0051] a rigid container 1001 built from panels and panel holders 1002 for easy assembly and disassembly, shipping and storing. In some embodiments of the invention the panels may be contain isolating materials, internally or externally.

[0052] The rigid container containing at least two flexible container made from Polyvinyl chloride (PVC), plastic, rubber, silicone, para-aramid synthetic fiber or the like that allows complete sealing of fluids and solids. At least one flexible container serves as a digester tank 1003 and at least one flexible container serves as a gas container 1004. The at least one container serves as a gas container is located higher than the At least one container serves as a digester tank.

[0053] The at least one container serves as a digester tank 1003 may be equipped with at least one intake pipe 1008 and at least one overflow pipe 1009. Both pipes ends lower than the height of the tank. In one embodiment of the invention, the pipe ends 15 cm below the top of the container serves as a digester tank. The at least one overflow pipe external opening is located higher than the bottom of the at least one container serves as a gas container. In one embodiment of the invention, the pipe ends 15 cm above the bottom of the container serves as a gas container. [0054] In some embodiments of the invention an opening for disposing of sludge and mud 1005 is provided beside the bottom of the at least one container serves as a digester tank. In some embodiments of the invention, the opening is a long PVC pipe; when not in use the pipe is rolled onto itself (much like a fire hose pipe).

[0055] At least one weight 1007 is laying on top of the flexible gas container 1004 hence creating pressure. The at least one weight's weight is calculated so that the pressure will not be high enough to create an overflow. The weight create pressure in the gas tank however the gas cannot escape to the digester tank and out due to the fact that the intake pipe and overflow pipe are located below the top of the digester tank.

[0056] In some embodiments of the invention the at least one weight is comprised of a set of rigid containers that may be filled with the appropriate amount of material, such as sand or dirt.

[0057] In some embodiments of the invention a plunger 2002 is provided within the intake pipe. The plunger may be submerged in the liquid that exist in the intake pipe. Once released, the plunger will move upward and float, when pushed down it will move all the floating portions of the waste downward into the digester. In some embodiments of the invention the plunger will be made out of floating materials and in different embodiments the plunger will be equipped with floats.

[0058] In some embodiments of the invention a manual grinder 2003 will be provided. The grinder will comprise an handle 2004 connected to an axle 2005 on which metal discs 2006 are provided. The discs will have a tooth 2007 going through a comb-like metal piece 2008 , hence grinding all that passes through the grinder.

[0059] In some embodiments of the invention at least two sinks are provided. The first at least one sink is adapted to be used with household waste 2009 and is equipped with a grinder. The second at least one sink is adapted to be used with non-household organic waste 2010 such as animal waste, manure etc. In other embodiments, said sinks will be placed one by the other with a trapeze or triangle casing 2011 whereby the grinder is located within the trapeze or triangle hence creating a one-piece household and non-household waste disposal location.

[0060] In some embodiments of the invention a filter is provided for disposing of the characterize sulfur smell and in order to stabilize and prepare the liquid part to be used in an hydroponic growing systems. The filter contain an air pump and bacteria substrate, hence the sulfur goes through a reduction process and the rest of the organic metirial goes through ammonification and mineralization processes producing NH4+ and NH3. Later the a nitrification process produce N02 and N03 which are suitable for agriculture. In some embodiments of the invention a complete hydroponic agriculture growing system is in fluid connection with the system hence supplied with said liquids on a regular basis.

[0061] Although selected embodiments of the present invention have been shown and described, it is to be understood that the present invention is not limited to the described embodiments. Instead, it is to be appreciated that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and the equivalents thereof.

Claims

1. An anaerobic digester adapted for production of fertilizer and biogas comprising:

a flexible tank serving as an anaerobic digester in fluid communication with said drain adapted to receive said slurry and non-household organic material and to facilitate a population of anaerobic bacteria which decomposes said materials into a liquid part and a gaseous fraction;

an overflow pipe;

gas distribution means adapted to distribute said gas from said gas reservoir.

wherein both biogas and fertilizer are produced and collected by an anaerobic digester.

2. The digester of claim 1 further comprising at least one weight adapted to create pressure on said at least one flexible tank serving as a gas reservoir.

3. The digester of claim 2 wherein said at least one weight comprising a set of weights filled with the appropriate amount of material to create a predefined pressure.

4. The digester of claim 3 wherein said overflow pipe opening is located higher than the bottom of the flexible tank serving as a gas reservoir.

5. The digester of claim 1 further comprising a plunger adapted to push or assist pushing of slurry into the digester tank, said plunger equipped with floats.

6. The digester of claim 1 further comprising at least one non-household organic material (such as manure or animal dumping) intake sink.

7. The digester of claim 1 further comprising at least one filter comprising at least one air pump and bacteria substrate.

8. An anaerobic digester adapted for production of fertilizer and biogas comprising:

a sink having a drain into which organic material is deposited; a grinder at the throat of said drain adapted to grind said organic material into a slurry;

an anaerobic digester in fluid communication with said drain adapted to receive said slurry and facilitate a population of anaerobic bacteria which decompose said organic material into a liquid part and a gaseous fraction;

a gas reservoir in fluid communication with said digester adapted to collect gas therefrom and store said gas in an inner chamber, said inner chamber being surrounded by fluid and open on its bottom;

gas distribution means adapted to distribute said gas from said gas reservoir;

9. The device of claim 8 wherein said gas reservoir is provided with a spillway for said fluid adapted to prevent said fluid from rising above a predetermined level.

10. The device of claim 8 wherein said fluid in said gas reservoir is water.

11. The device of claim 8 wherein said grinder is hand operated.

12. The device of claim 8 wherein said grinder is automated.

13. The device of claim 8 wherein said digester is provided with substrates 207 having high surface area adapted to promulgate the formation of anaerobic bacteria colonies.

14. The device of claim 8 wherein having fertilizer production rates of approximately 8 liters per day and gas production rates of approximately 1 m³ per day from a single-household waste stream.

15. The device of claim 8 wherein said gas reservoir is provided with a pressure gauge.

16. The device of claim 8 wherein said gas is used for purposes selected from the group consisting of: lighting; electricity generation; motive power; combustion; cooking; heat production; air heating; water heating.

17. A method for production of fertilizer and biogas comprising steps of:

providing a sink having a drain into which organic material is deposited;

collecting the gaseous fraction of said digester in a gas reservoir in fluid communication with said digester adapted to collect gas therefrom and store said gas in an inner chamber, said inner chamber being surrounded by fluid and open on its bottom;

distributing said gas using gas distribution means adapted to distribute said gas from said gas reservoir; wherein both biogas and fertilizer are produced and collected by an anaerobic digester operating at high production rates.

18. The method of claim 17 wherein said anaerobic digester and said gas reservoir are comprised of flexible tanks.

19. The method of claim 18 wherein said gas reservoir is provided with a spillway for said fluid adapted 18 prevent said fluid from rising above a predetermined level.

20. The method of claim 18 wherein said fluid in said gas reservoir is water.

21. The method of claim 18 wherein said grinder is hand operated.

22. The method of claim 18 wherein said grinder is automated.

23. The method of claim 18 wherein said digester is provided with substrates having high surface area adapted to promulgate the formation of anaerobic bacteria colonies.

24. The method of claim 18 wherein having fertilizer production rates of approximately 8 liters per day and gas production rates of approximately 1 m per day from a single-household waste stream.

25. The method of claim 18 wherein said gas reservoir is provided with a pressure gauge.

26. The method of claim 18 wherein said gas is used for purposes selected from the group consisting of: lighting; electricity generation; motive power; combustion; cooking; heat production; air heating; water heating.