WO2025160670A1

WO2025160670A1 - System for converting carbon-based waste to biocarbon and promoting plant growth and compost production

Info

Publication number: WO2025160670A1
Application number: PCT/CA2025/050123
Authority: WO
Inventors: Christy Dawn SKELTON
Original assignee: Individual
Current assignee: Individual
Priority date: 2024-01-30
Filing date: 2025-01-30
Publication date: 2025-08-07
Anticipated expiration: 2026-07-30
Also published as: CA3227632A1

Abstract

A current burden (garbage) is turned into a resource (biocarbon, such as biochar) while heat from the pyrolysis reaction is used to heat soil in a greenhouse for supporting plant growth. The heat is provided by underground pipes that keep the soil warm while excess heat from warming the soil warms a composting area. This is arranged such that CO2 produced during composting is respired by the plants in the greenhouse while oxygen produced by the plants promotes the composting reaction. Biochar produced by the pyrolysis reaction can then be mixed with compost tea produced from the compost which can be used as a soil amendment product.

Description

SYSTEM FOR CONVERTING CARBON-BASED WASTE TO BIOCARBON AND PROMOTING PLANT GROWTH AND COMPOST PRODUCTION BACKGROUND OF THE INVENTION

Disposal of waste, for example, household waste or garbage, presents a significant problem. Specifically, disposing of waste in for example a landfill costs money and uses land that could be put to other purposes.

While recycling programs and limited composting programs have reduced the amount of waste entering landfills somewhat, more needs to be done to convert household waste into useful products.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a method of heating soil for plant growth comprising: providing:

(a) a planting area comprising a plurality of plants planted in soil of the planting area and a closed loop pipe system beneath a surface of the soil, said planting area being covered such that the plurality of plants are exposed to natural light but not to outside weather conditions;

(b) a heat source for converting biocarbon from waste;

(c) a heat exchanger collecting heat from the heat source, said heat exchanger connected to the closed loop pipe system and a pump; heating a quantity of a noncompressible fluid in the closed loop pipe system by converting a quantity of waste into biocarbon within the heat source; pumping the quantity of heated noncompressible fluid through the closed loop pipe system, thereby heating the soil in which the plurality of plants are planted.

According to another aspect of the invention, there is provided a system for converting carbon-based waste to biocarbon and promoting plant growth and compost production comprising:

(a) at least one greenhouse comprising a planting area of soil having a plurality of plants planted in the soil and a closed loop pipe system beneath a surface of the soil, said planting area being covered by the greenhouse such that the plurality of plants are exposed to natural light but not to outside weather conditions;

(b) a pyrolysis kiln for carrying out a pyrolysis reaction to convert carbonbased waste to biocarbon;

(c) a heat exchanger receiving heat from the pyrolysis reaction and using said heat to heat a quantity of heat exchange fluid;

(d) a pump connected to the closed loop pipe system for piping heated heat exchange fluid through the closed loop pipe system, thereby heating the soil of the planting area; and

(e) a composting area for converting compostable waste into compost, said composting area arranged to exchange air with the at least one greenhouse.

According to another aspect of the invention, there is provided a method for converting carbon-based waste to biocarbon and promoting plant growth and compost production comprising: providing a system comprising:

(a) at least one greenhouse comprising a planting area of soil having a plurality of plants planted in soil and a closed loop pipe system beneath a surface of the soil, said planting area being covered by the greenhouse such that the plurality of plants are exposed to natural light but not to outside weather conditions;

(b) a pyrolysis kiln for carrying out a pyrolysis reaction to convert carbon-based waste to biocarbon;

(e) a composting area for converting compostable waste into compost, said composting area arranged to exchange air with the at least one greenhouse; burning a quantity of carbon-based waste in the pyrolysis kiln, thereby producing heat and biocarbon; the heat exchanger using the produced heat to heat the heat exchange fluid; pumping the heat exchange fluid through the closed loop pipe system, thereby heating the soil in the plant growing area and promoting growth of the plants compared to plants of similar type grown in unheated soil, said plants respiring carbon dioxide produced in the composting area and producing oxygen for promoting compost production.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram of one embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now described. All publications mentioned hereunder are incorporated herein by reference.

Described herein is a method and a system for converting waste to useful products.

Specifically, described herein is a system that combines a pyrolysis kiln to convert waste, for example, household garbage, to biocarbon, for example, biochar, biocoke or biocoal, depending on the size of the particles, and using the heat from the biochar reaction to heat a greenhouse and a composting site and then combining the biocarbon, for example, biochar produced with the compost tea produced from the compost to form a soil amendment product.

As used herein, “greenhouse” refers to any building used to grow plants, but is preferably a building for growing plants in which natural light is a light source, for example, a primary light source, as discussed herein. As discussed herein, the system and the method of using the system reduce the amount of waste, for example, carbon-based waste, for example, carbon-based household garbage that is disposed of in landfills as the system converts waste into biocarbon, for example, biochar while using the heat, for example, excess heat, from the biochar reaction to produce compost tea and compost, while also providing heat that supports growth of plants, particularly in cold climates.

As discussed herein, in some embodiments, the system and method of using the system is preferentially used in “cold” climates, for example, in USDA agriculture zones 8 and below. Specifically, as known to those of skill in the art, generally zones 6 and below but some zones 7 and 8 get snow in the winter. That is, the system can be used such that plants can be grown in these zones, that is, zones that experience at least some snow cover on the ground, year-round.

In one embodiment of the invention, there is provided a heat source, a composting area and a plant growth area.

As discussed above, anything that produces waste heat can be used as the heat source. However, most processes that have excess heat bum hydrocarbons, which is a cost. As such, in a preferred embodiment, the system of the invention uses a current burden (garbage) and turns it into a resource (biocarbon, for example, biochar produced from the waste, heat from pyrolysis reaction promotes plant growth, plant growth prevents production of anaerobic compost, and compost is used to produce compost tea, which is mixed with biochar to form a soil amendment product).

In some embodiments of the invention, the heat source is a device for producing biocarbon, such as biocoke, biocarbon or biochar, for example, a pyrolysis kiln.

In a preferred embodiment of the invention, a pyrolysis kiln is used which collects the off-gasses and re-injects them into the pyrolysis chamber. This means that the kiln bums at a much higher temperature relative to the amount of feedstock, creating a larger amount of waste heat.

In contrast, other biochar kilns that collect the off-gasses but don’t re-inject them will create only about 40% of the amount of waste heat produced by a re- injection kiln. These units are typically also much larger units and will require a much larger population base.

In the embodiment shown in Figure 1 , the system comprises a pyrolysis kiln as the heat source and has a composting area flanked on either side by a greenhouse. As discussed below, in these embodiments, the greenhouse(s) and the composting area are placed directly on the soil. That is, plants grown in the greenhouse(s) are planted directly into the soil and composting of suitable waste takes place directly on the soil as well. Furthermore, the composting area and the greenhouses are connected such that O2 from the greenhouses will feed the composting area while any excess CO2 produced during the composting process is taken up by the growing plants, thereby establishing what is in effect an ecosystem that establishes cooperative plant growth that is supported by heat produced by the pyrolysis reaction and compost production that is supported by growing plants using CO2 produced during the composting process, as discussed herein.

As used herein, “planted directly in the soil” refers to the fact that the plants are not being planted in pots, planters or troughs that hold potting soil but rather are being planted directly in the soil, that is, in native soil or ground that has been tilled for planting, similar to an agricultural field.

As will be appreciated by those of skill in the art, any carbon-based waste can go through the kiln. This typically represents about 92% of the garbage currently going to landfills.

Accordingly, in some embodiments of the invention, incoming garbage is sorted or has been sorted into pyrolysis kiln feedstock, compostable waste and landfill waste.

In some embodiments of the invention, the pyrolysis kiln is connected to or is in communication with a heat exchanger such that waste heat from the biochar kiln is applied to the heat exchanger and is used to heat a suitable heat exchange fluid which is then circulated by pumping means such as a pump throughout the greenhouse in pipes, as discussed below. It is noted that forced air heating is typically used in systems for heating greenhouses. However, while forced air heating systems are efficient in smaller systems, once you get above about 3000 sq ft, the efficiency drops off precipitously.

In some embodiments of the invention, any suitable non-compressible fluid or material, for example, water or a glycol mix is used as the heat exchanger fluid.

As discussed herein, the pipes are inserted below ground level at a suitable depth for providing heat to the roots of the plants. As will be appreciated by those of skill in the art, the roots of the plants may (and likely will) grow below the level of the pipes. However, placement of the pipes close to the surface of the ground or soil allows for the soil to be kept at a suitable growing temperature. As discussed herein, the pipes can be arranged such that they are along an outer perimeter of the greenhouses. In some embodiments, the pipes may also be placed such that the pipes provide heat between adjacent rows of plants. For example, a “suitable depth” may be less than 10 feet deep, less than 9 feet deep, less than 8 feet deep, less than 7 feet deep, less than 6 feet deep, less than 5 feet deep, less than 4 feet deep, less than 3 feet deep, less than 2 feet deep or less than 1 foot deep, that is, less than 1 foot below the surface of the soil of the planting area.

Specifically, it was previously believed that the leaves of the plant needed to be at a suitable temperature for growth. However, more recent research says it is more important for the roots to be at the suitable temperature.

As will be appreciated by those of skill in the art, forced air heating can only be transmitted through the air. While forced air is suitable for keeping plants warm, using heated air to warm soil and especially roots below the soil is inefficient.

In contrast, pumping a heated liquid through a pipe is much more efficient than blowing air (less than 50% required energy to move similar amount of heat a similar distance). Furthermore, once the soil is heated, the excess or remaining heat rises from the soil and heats the air, thereby heating the rest of the building.

In the embodiment shown in Figure 1 and as discussed below, the pipes are placed in the ground, that is, below the surface of the soil or ground, around the perimeter of the greenhouse building(s), for example, such that the pipes run underground along the side of any exterior wall. Furthermore, as discussed herein, the plants are planted directly into the soil on which the greenhouse has been built, that is, the soil that is being covered by and protected or sheltered from the elements or environmental conditions or cold weather by the greenhouse building.

As known to those of skill in the art, frozen ground next to warm soil will continuously leach heat from the warm soil, that is, soil that is being heated by the circulation of the heat transfer fluid in the closed loop pipe system, which will in turn reduce the amount of heat available to heat the greenhouse building. Furthermore, greenhouses are generally heated to about plus 25C year-round. Thus, maintaining soil temperatures by heating the soil as the weather beings to cool and by placing insulating material, for example, hay bales or another site-specific suitable insulating material, along the outside surfaces of the exterior walls, specifically, on top of the ground immediately outside of the exterior walls of the greenhouse(s), all of the soil within the growing areas can be kept at the desired growing temperature, for example, 25C, by placement of the pipes along the perimeter of the greenhouse corresponding to the exterior walls. For example, the insulating material may extend up to four feet from the outer surface of the exterior walls on the surface of the outside ground, that is, the ground immediately outside of the exterior walls of the greenhouse(s).

In some embodiments, the pipes are placed in the ground within 4-6 feet of an exterior wall. In some embodiments of the invention, pipes may be placed along the exterior walls. In yet other embodiments of the invention, as discussed herein, a separate set of pipes may be placed along the roof or roofs of the building or buildings of the complex for melting snow.

In some embodiments of the invention, the plants inside the greenhouses are provided natural light, for example, through glass or through a suitable light- permeable polymer. In some embodiments, the greenhouse may include additional light sources for promoting plant growth.

In some embodiments of the invention, the north side of the greenhouse building is insulated such that it is largely impermeable to light. Specifically, in the northern hemisphere, the north side of a building only loses heat in the winter and doesn’t contribute to light gathering. This means it’s just a liability and should be insulated.

In some embodiments of the invention, there is provided roof piping which is placed throughout the roof of the greenhouse, for example, along joists, beams or joints thereof, and the roof piping is connected either directly or indirectly to the pump such that heat exchange fluid can flow therethrough. In this manner, the heat can be sent to the points in the roofing system that accumulate snow on an as needed basis in order to remove any excess weight from the snow. As such, in some embodiments, the roof piping may be controlled separately from the pipes placed in the ground.

As discussed above, in some embodiments, the compost and greenhouse buildings may be adjacent to each other to allow for air flow. In other embodiments, the composting area and the plant growing areas may be in different buildings with conduits between buildings to transfer CO2 from the compost building to the plant growth buildings (greenhouses) and to transfer O2 from the plant growth buildings to the compost building. However, as will be apparent to those of skill in the art, it is more efficient to have open air flow.

In some embodiments of the invention, the composting area comprises a turner that mixes the composting material. In some embodiments, the turner is arranged such that the turner contacts the surface of the soil or ground so that full mixing of the compost is achieved.

As will be appreciated by those of skill in the art, during the composting process, the compost temperature is measured periodically, for example, daily. Once the compost has reached a suitable temperature after each mixing, the compost is allowed to sit or stabilize and is then tested for microbial activity. Once a suitable, desirable or appropriate ratio of bacteria to fungi has been attained, the compost is done and at least a portion thereof can be moved or stored.

As shown in Figure 1 , in some embodiments, the radiant heat is around the greenhouse perimeter or “envelope”. As a result of this arrangement, the exterior walls of the greenhouses and therefore the building complex are not leaching heat, meaning that the compost will create its own heat. This is critical because, in, for example, Canada, compost operations typically shut down during the winter because they must be open to the elements. If a typical composting building is enclosed, the CO2 levels get too high and the compost turns anaerobic, which renders it toxic. By attaching it to a greenhouse, which uses the CO2 and produces oxygen, everything can be enclosed and still operate at maximum efficiency, especially during the winter months.

As shown in Figure 1 , the greenhouse(s) and the composting area may include fans for regulating the airflow therebetween, such that if necessary O2 from the greenhouses can be directed into the composting area and/or CO2 produced by the composting can be directed into the greenhouses for consumption by the plants.

In the embodiment shown in Figure 1 , the system 1 comprises a kiln room 10, a composting area 20 and two plant growth areas 30 on either side of the composting area 20. In this embodiment, the kiln room is housed in one building or one room of the complex, the composting area 20 is housed in a composting room and the plant growth areas 30 are housed in greenhouses. As discussed herein, these may each be in separate buildings or, as shown in Figure 1 , may be in a single complex housed under one roof. It is further of note that in some embodiments, the buildings and/or complex comprise side walls and a roof but no man-made flooring such as a concrete pad. Specifically, this allows for plants to be planted directed into soil and for the compost to be turned, as discussed herein. More importantly, the complex can be moved to a different location if necessary or at an appropriate time without having damaged or harmed the underlying ground conditions.

The kiln room 10 comprises a pyrolysis kiln 12 and a heat exchanger 14 which is connected to a pump 16 for circulating a heat transfer fluid, as discussed below. As discussed above, waste, for example, carbon-based waste, for example, carbonbased household garbage is placed into the kiln and burned, thereby producing biocarbon, for example, biochar. Excess heat from this reaction enters the heat exchanger and is used to heat the heat transfer fluid, as discussed below.

As discussed above, the pyrolysis kiln 12 is preferably arranged for re-injection of off-gasses. The compost area 20 comprises an area of soil onto which compostable waste is placed directly. In some embodiments, the compost area 20 includes a turner for mixing the compost, as discussed above.

The greenhouse 30 comprises planting areas 32 wherein plants are planted directly into the soil.

The planting areas 32 further comprise pipes 34 which are placed along the perimeter of the of the greenhouse area, for example, at a suitable depth for heating the roots of the plants planted in the planting areas 32, as discussed above.

As can be seen in Figure 1 , the pipes 34 extend along three sides of each greenhouse 30, that is, along the exterior walls 36 of the greenhouses 30.

As discussed above, in some embodiments of the invention, additional roof piping is provided which extends from the pump 16 either directly or indirectly (for example, by connection to the pipes 34) to the roof of the complex building, particularly at junctions thereof and/or at regions wherein snow is known to accumulate for melting snow gathering thereon, thereby reducing weight of snow on the room of the complex building.

In some embodiments, the roof piping can be connected such that earth deeper below the ground surface, for example, ground about 6 feet under the surface, which is typically 5C year round, and then be used to cool off the highest air, that is, air that is being heated by exposure to sunlight.

For use during cold weather months, the pump 16 is connected to pipes 34. As a result of this arrangement, the soil within the planting areas 32 are kept to a temperature of approximately 25C.

Specifically, the temperatures in various parts of the building are regulated by a system of controls and sensors, similar to a residential or commercial building.

Furthermore, the parts of the building may include CO2 sensors for instructing the system to activate fans to remove any excess CO2 produced during compost production from the compost building and distributing the excess CO2 into the greenhouses, as discussed above. It is of note that a pyrolysis kiln can use 1200 Ib/hr of carbon-based waste, which is roughly equivalent to the amount of garbage thrown away by about 8,000 average Canadians. The waste heat generated from this amount of garbage, using the pyrolysis kiln that reinjects the gasses, described above, can heat 100,000 sq ft of building space, assuming an average amount of insulation in the building walls and assuming that the difference between the interior and exterior temperatures is 60C (i.e. exterior of the complex building is minus 30C and interior of the complex building is plus 30C).

In use, the temperature of the greenhouses is monitored during the late summer and early fall and as the average temperature of the greenhouse decreases to below 25C, appropriate carbon-based waste, for example, carbon-based household garbage, is placed into the pyrolysis kiln, so that heated circulating heat exchange fluid can heat or warm the planting areas or soil as discussed herein.

It is of note that in some embodiments, during warm weather months, the carbon-based waste can be saved for cold weather months. Alternatively, the pyrolysis kiln can be run year-round and during warm weather periods, the excess heat can be repurposed, for example, for water purification and/or distillation.

It is important to note that at this point in time, at least some plants have already been planted in the growing soil covered by the greenhouses and composting of compostable waste has been taking place in the composting area during warmer weather.

As discussed above, the carbon-based waste or garbage acts as feedstock for the pyrolysis kiln. As known by those of skill in the art, pyrolysis typically occurs at temperatures between 800F-1400F. The pyrolysis reaction needs energy input, such as hydrocarbons or green Woodstock to start but once established, pyrolysis will continue as long as more carbon-based feedstock is added.

As the garbage is converted to biocarbon, for example, biochar, the end product of the pyrolysis reaction is removed from the pyrolysis kiln and is cooled by spraying with water. The size of the biochar particles will somewhat be determined by the feedstock but in general, they will be about dime size or lower. As biochar is removed, more carbon-based feedstock or garbage is added to the pyrolysis kiln. This process may be facilitated by any suitable means known in the art, for example, by a conveyor belt system or the like.

Excess heat from the pyrolysis reaction is transferred via the heat exchanger to the heat exchange fluid in the pipes that are connected to the pump. As discussed above, these pipes are buried in the ground and/or along the exterior walls of the greenhouse. The circulation of the heated heat exchanger fluid through the pipes heats the ground that corresponds to the growing soil. Furthermore, insulating material placed on the exterior soil that borders the exterior walls of the building or buildings of the complex helps to keep the soil at the desired temperature.

As discussed above, the temperature of at least the greenhouses is monitored and if the temperature drops below a certain level, the flow of the heated liquid is adjusted, for example, increased.

Alternatively, if the temperature of the greenhouses is too high, the piping system may be switched from heating (being distributed by a pump while connected to the heat exchanger) to cooling (by distributed by a separate pump connected to a geothermal heat sink or geothermal cooling system), as discussed herein.

The amount of CO2 in the composting area is also monitored and if the CO2 levels are above a threshold, the fans 40 between the greenhouses and the composting area may be engaged to draw off CO2 for the plants and/or provide O2 produced by the growing plants to the composting area, thereby improving the efficiency and productivity of both the plant-growing and compost-producing processes. In some embodiments of the invention, this is done by continuous air exchange.

The typical vegetables grown in Canadian greenhouses are tomatoes, cucumbers and sweet peppers. By planting on a schedule, users can harvest on a weekly basis year-round.

Once removed, the biochar and the compost are stored separately.

In some embodiments, compost will be removed approximately every two weeks. Piles will be made daily so there will be continuous compost production. Prior to shipping, compost tea is made will be made, and then the biochar is mixed with compost tea.

Compost tea extracts the soil biology from the solid compost material. This cuts down on the weight of the product. The soil biology must be aerated because once it turns anaerobic, it is useless and/or damaging to plants. Traditionally, in order to ship compost tea, it must continually have air incorporated, which is not easy to do. However, mixing the compost tea with the biochar solves this problem and provides the benefit of compost without the cost of shipping the higher weight product.

As will be appreciated by those of skill in the art, compost tea can be produced from compost by placing the compost in a vessel of water that further comprises an agitator and an air-bubbler. As discussed above, the compost is tested for temperature and for bacteria:fungi ratio. Once the desired ratio has been attained, the compost is removed from the composting area. Compost tea can then be made from the removed compost as needed. Following compost tea production, the residual compost can be returned to the composting area for what can be considered regeneration or can be applied to other locations as a soil remediation product or similar purposes known in the art.

In some embodiments, the ratio of fungi to bacteria is for example 0.8-1 .2:1 or 0.85-1 .15: 1 or 0.9-1 .1 : 1 or 0.95-1 .05: 1 or approximately 1 : 1 . As will be appreciated by those of skill in the art, the bacterial activity is what causes the heat and the majority of CO2 production. However, as bacterial growth slows down, fungal growth continues. Once the desired ratio is achieved, the compost tea is appropriate or suitable for most plants.

Because compost tea has to be continuously oxygenated, it is difficult to ship on its own. However, mixing compost tea with biocarbon such as biochar will allow the tea to be aerated without mechanical agitation.

The amount of compost tea will be determined by the saturation level of the biochar before mixing. Typically, biochar comes out of the kiln at 18% moisture. The biochar is then saturated with the compost tea to about 95% (as high as we can go without risking saturation and consequently anaerobic conditions being created). The biochar nearly saturated with compost tea can be sold for example to farmers that have marginal land that is prone to drought. The product is marketed as a soil amendment and not a fertilizer as it does not need to be added annually. One application will make a permanent change to the soil. These changes include but are not limited to increasing the water retention capacity of the soil, and improving the soil biology which will in turn encourage root growth, which in turn allows the plants to access soil nutrients more easily.

While the preferred embodiments of the invention have been described above, it will be recognized and understood that various modifications may be made therein, and the appended claims are intended to cover all such modifications which may fall within the spirit and scope of the invention.

Claims

1 . A method of heating soil for plant growth comprising: providing:

(b) a heat source for converting biocarbon from waste;

2. The method according to claim 1 wherein the heat source is a pyrolysis kiln.

3. The method according to claim 1 wherein the soil is native soil.

4. A system for converting carbon-based waste to biocarbon and promoting plant growth and compost production comprising:

5. A method for converting carbon-based waste to biocarbon and promoting plant growth and compost production comprising: providing a system comprising:

6. The method according to claim 5 wherein the compost is used to produce compost tea.

7. The method according to claim 6 wherein the biocarbon is biochar and the biochar is mixed with the compost tea.

8. The method according to claim 7 wherein the biochar is mixed with the compost tea such that the biochar is no more than 95% saturated with compost tea.

9. The method according to claim 5 wherein the closed loop pipe system is placed beneath the surface of the soil along exterior walls of the at least one greenhouse.

10. The method according to claim 5 wherein the at least one greenhouse and the composting area are adjacent to one another such that exchange of air is by natural airflow.

11 . The method according to claim 9 wherein insulating material is placed on soil immediately outside of the exterior walls of the at least one greenhouse.

12. The method according to claim 5 wherein the soil is soil that typically has snow cover at least part of the year.

13. The method according to claim 5 further comprising a roof closed loop pipe system in contact with at least a portion of a roof of the at least one greenhouse, said roof closed loop pipe system connected to the heat exchanger and a pump for pumping the heat exchange fluid through the closed loop pipe system, thereby melting snow on the roof of the at least one greenhouse.