GB2596790A

GB2596790A - Device and method for producing CO2 using fermentation for the purpose of facilitating the growth of plants

Info

Publication number: GB2596790A
Application number: GB2009975.0A
Authority: GB
Inventors: Andrew Coutts Calum
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2022-01-12
Also published as: GB202009975D0

Abstract

Provided is a carbon dioxide generator suitable for promoting the growth of plants. The generator operates by dosing sugar, or a sugar-containing product, into a fermentation vessel 3 at a specific rate in order to control the rate at which carbon dioxide is produced. The sugar can be dosed into the fermentation vessel 3 by a dosing mechanism (11, Fig. 3) controlled by a micro-controller and an associated motor (10, Fig. 3); and the dosage rate can be determined by a PID control algorithm that calculates the required rate to achieve a specific CO2 concentration, or can be chosen by a user. The sugar can be fed from a hopper 1 into the fermentation vessel by a rotary/screw feeder; and dispersed into a surrounding plant-growing environment by a fan 4.

Description

Device and method for producing CO2 using fermentation for the purpose of facilitating the growth of plants CO2 is an essential component for plants to photosynthesize and grow. During photosynthesis, plants use light energy to convert CO2 and water into sugars. These sugars are then used for growth within the plant. It has been found that for most crops, elevating CO2 in the growing environment increases the productivity of the plants, typically between 10% and 40%, resulting in higher and/or earlier yields for farmers. Another benefit of CO2 supplementation is that it can make plants more tolerant to higher temperatures.

CO2 supplementation is already being used by growers of vegetables and fruit in greenhouses and in buildings or other enclosed spaces under artificial lighting. There are several different technologies currently being used. Large scale operations with mains gas often utilize 'CO2 cannons' that burn natural gas to produce the CO2. Where these are not a viable, maybe due to lack of mains gas, safety concerns or unwanted heat generation then compressed gas can be brought in and released into the environment from cannisters or a large tank using a regulator. The start-up costs for both methods are usually too expensive for the small scale or hobby grower. Smaller scale and hobby growers often use products such as 'CO2 bags', bags of fungus and organic matter that produce co2 when the fungus grows, dry ice that is allowed to melt and release CO2 and tablets that are dissolved into water to produce CO2 but these methods are relatively ineffective as they are unstable, expensive and do not usually increase the CO2 concentration by a significant degree.

An alternative method for producing CO2 is through fermentation of sugar using yeast. The amount of CO2 that can be produced in this way and the cost of sugar relative to the quantity of CO2 produced makes this a very viable option. However, the difficulty with this method comes with controlling the rate at which CO2 produced. Simply mixing sugar, water and yeast will result in an exponential spike in CO2 levels and then a rapid decay, usually overshooting the desired CO2 concentration limit. This would not be optimal for plant growth and may create levels of CO2 dangerous for humans. To overcome this problem, the present invention proposes a device that doses sugar into a fermentation vessel at an incremental rate so that CO2 levels can be elevated and maintained within set limits.

According to its broadest aspect the invention is a device that takes sugar from a hopper (1) and doses it into a fermentation vessel (3) at a suitable rate so that the level of CO2 in the local atmosphere is maintained within set limits.

The accompanying renders represent a preferred embodiment of the invention and were selected for the purpose of illustration and consequently should not be construed as a restrictive of the invention.

Referring to the renders, figure 1 shows a fermentation vessel (in the context of this description, the term 'fermentation vessel' refers to any vessel suitable for the fermentation of sugar or any product containing sugar) partly full of a mixture containing sugar, yeast cells and water. On the lid of the fermentation vessel there is a device (2) that doses sugar from a hopper (1) using a rotary feeder connected to a motor (10) and controlled by a microcontroller (in the context of this description, the term imicrocontroller' refers to any type of suitable computer) (8). There is a screen (7) for displaying co2 levels as measured by a co2 sensor (not shown), the Co2 setpoint and the temperature. On the lid of the fermentation vessel is an air lock (2) that allows the Co2 to escape and a fan (4) that disperses the Co2 throughout the growing environment. The lid is sealed to the fermentation vessel so that no gases can escape, apart from through the airlock. There are buttons (9) on the device so that the user can input the desired co2 level setpoint. The device is powered by a 12v power supply or a rechargeable battery (not shown).

In the preferred embodiment of the invention, a CO2 sensor is used to monitor and feedback CO2 levels in the growing environment to the microcontroller. The CO2 sensor could be located within the dosing device or could be remote. A PID algorithm, or similar algorithm, running on the microcontroller then uses this data to determine the rate at which sugar needs to be dosed into the fermentation vessel to achieve or maintain the desired CO2 setpoint. The microcontroller then uses this information to drive a motor (10) connected to the dosing mechanism (11) thereby controlling the rate at which sugar is dosed into the fermenter. The microcontroller would preferably be connected to the internet so that the data could be uploaded to the cloud and viewed using a device such as a smartphone or pc running an application dedicated to the purpose.

In the preferred embodiment of the invention the fermentation vessel would include a tap located close to the bottom (not shown in the renders) so that the fermented mixture could be more easily drained or else decanted into containers for later use. A tap close to the bottom of the vessel as opposed to the bottom of the vessel would be preferable since it would prevent the yeast that settles on the bottom of the vessel from being decanted.

Figure 4 is a chart showing CO2 levels over time period of 480 minutes in a semi sealed grow room without any CO2 supplementation, Figure 5 is the same but shows what happens to CO2 levels when 500g of sugar is dumped at once into a fermentation vessel with active, fast-fermenting yeast and figure 6 is the same but shows what happens to CM levels when the apparatus described above is used to dose sugar into the vessel incrementally. Figure 6 shows that the apparatus described above can effectively elevate CO2 levels and maintain CO2 levels at a desired setpoint.

Figure 7 is a chart showing the inputs and outputs from the device's microcontroller in the preferred embodiment of the invention.

The device would preferably have a light sensor (not shown) so that the microcontroller knows when it is light and dark. When it is dark, plants do not photosynthesize so CO2 production could be suspended during this period in order to preserve sugar. When there is less light than what is optimal the device could be programmed to lower the CO2 setpoint since less CO2 can be used by the plants when there is less light.

The device would also preferably have at least one temperature sensor. Plants are unable to use as much CO2 if the temperature is either too hot or too cold so this data could also be used to adjust the CO2 setpoint. This data could also be used to alert the user if temperatures become less than optimal for plant growth if the device was connected to the internet and capable of sending such data.

In another variation of the invention, no Co2 sensor is used, and the dosing rate is based on the size of the environment that is being supplemented with Co2 and the level of ventilation. This information could be input into the device using buttons located on the device (9) or by any other means. This embodiment of the device would be less expensive to produce but would limit the devices capabilities for controlling the precise level of Co2 present in the environment.

In another variation of the invention, no fan is used and instead, a hose goes from the outlet on the fermenter to the top of the growing space so that the CO2 can be distributed evenly over the cultivated plants. Since CO2 is heavier than air, the CO2 will 'rain' down onto the plants. This variation of the invention may be better suited to growing environments where there is less air movement.

In another variation of the invention the fermentation vessel would be positioned outside of the environment being supplemented with CO2 with a hose connecting the fermentation vessel to the environment.

Example and Calculations To start the process the fermentation vessel is partially filled with warm water (30°C -50°C) a quantity of sugar is added and then some fast-acting yeast sprinkled on top of the mixture and then the lid is sealed over the fermentation vessel. For 20L of water, 100g of sugar and 140g of fast acting yeast appears to be a good ratio so that initial fermentation starts abruptly and does not take too long to finish. After a period (usually around 10 minutes for this ratio of sugar, water and yeast at this temperature) the yeast becomes active and starts to consume the sugar whilst producing CO2 and ethanol as shown in the formula bellow: C6F11206 4 2 C2H5OH + 2 CO2 During this period the yeast cells multiply exponentially so that the rate of fermentation also increases exponentially. Fermentation can be observed by looking for bubbles in the bubbler. When the bubbles slow down, typically after around 2 -3 hours, this indicates that most of the sugar has been consumed by the yeast. The device can then be turned on so that it can add more sugar, as required, to the vessel in order to restart the fermentation and generate CO2. The device may be programmed so that it turns on itself after a set period in order to prevent the user from needing to revisit the device. The yeast cells will continue to multiply until they reach a saturation point. This step of the process could be done inside of the space being supplemented or outside without risk to human or plant life as the at which CO2 is being produced is relatively small.

As the sugar is consumed, the alcohol level in the liquid mixture will increase, eventually the alcohol would kill the yeast if its concentration were allowed to get above a certain point, typically at around 15% alcohol. For this reason, the fermenter needs to be periodically emptied and refilled. The mixture could either be partially emptied and refilled, leaving enough yeast to continue the fermentation, whilst lowering the alcohol content or the vessel could be completely emptied and restarted with fresh yeast. The mixture that is emptied from the fermenter could be consumed as an alcoholic beverage or distilled into spirit. Flavour enhancers such as concentrated fruit juice or artificial flavourings and sweeteners may be added to the mixture to improve the taste. These may also have the benefit of imparting flavours into whatever crop is being cultivated in the environment that is being supplemented with CO2. Or additives especially for the purpose of imparting flavour into whatever is being cultivated may be used for this purpose.

The maximum amount of sugar that can be added to the vessel before the liquid mixture would need to be changed, can be calculated using the 'balling formula' which states that when 2.0665g of sugar is fermented, 1g of alcohol is produced, 0.11g of yeast and 0.9565g of CO2. Therefore, to hit 15% alcohol in a mixture of 20 L: 201 is roughly 20,000g 15% of 20,000g = 3000g of alcohol Using the 'balling formula' 3000g of alcohol would require 3000 x 2.0665 = 6,119.5g of sugar The amount of CO2 produced from this 6.1195Kg of sugar can be calculated using the same formula as 3000 * 0.9565 = 2869.5g of CO2 The amount of CO2 by volume in an 8m2 grow space with a co2 concentration of 1000ppm can be calculated as: 8*0.001 = 0.008m2 of CO2.

At standard temperature and pressure, the density of carbon dioxide is around L98 kg/rn3 So to convert this into grams we can multiply the volume of co2 by its density: 0.008 * 1980 = 15.84g Assuming a full air exchange every 2 hours, typical for a tight greenhouse or grow room and assuming 18 hours of light we can calculate how much CO2 we would need in a day: (18/2) * 15.84 = 142.56g of CO2 Converting back into grams of sugar: 142.56 * (2.0665/0.9565) = 308g These calculations do not consider the CO2 actually consumed by the plants. The amount of CO2 sequestered would depend on several factors, but a very rough estimate can be made.

If after 6 months the total weight of plant matter was 5kg, a typical plant is composed of 40% carbon so we could presume that 0.4*10 = 2kg of CO2 had been sequestered by the plant.

CO2 is composed of one molecule of Carbon and 2 molecules of Oxygen.

The atomic weight of Carbon is 12.0011.

The atomic weight of Oxygen is 15.9994.

The weight of co2 is C + 2*0 = 43.999915. So the ratio of CO2 to Carbon is 43.9999/12.0011=3.666 Therefore, the weight of CO2 sequestered by the plants in the 8m2 grow space in the 6-month period could be presumed to be 3.6663 * 2 = 7.33Kg CO2 7.3kg of CO2, based on the balling formula would represent 7.3*(2.0665/0.9565) =1g.< of sugar. Expressed as a percentage of the total sugar consumed this is (15.8/(0.308*180))*100 = 28.6%. Therefore, we could multiply the figure that we calculated for sugar consumption / day by 28.6%. 308*1.286 = 396g of sugar / day. Though it should be noted that less than this would be consumed at the beginning and more towards the end of the grow.

So 6kg of sugar would last 6000/396 = 15.5 days roughly. Therefore, the fermenter would have to be refilled approximately every 2 weeks. The device could be programmed in a way so that it alerts the user when the mixture needs emptied with either an audible alert or notification sent to a mobile device if it were to be connected to the internet.

Claims

SCLAIMS1. Carbon dioxide (CO2) generator intended, among other possible uses, to promote the growth of plants, characterized by the fact that the generation of CO2 is achieved by fermentation of sugar or any product containing sugar and where sugar is dosed into a fermentation vessel (3) at a specific rate in order to control the rate at which CO2 is produced.
2. Device according to claim 1 that uses either a rotary feeder or screw feeder to dose sugar from a hopper (1) into the fermentation vessel (3).
3. Device according to any one of the preceding claims, characterized by the fact that it has at least one sensor capable of measuring CO2 so that the concentration of CO2 in the space being supplemented can be measured.
4. Device according to claim 3, characterized by the fact that it uses a PID control algorithm running on a microcontroller to calculate the rate at which sugar should be dosed into the fermentation vessel in order to achieve a specific concentration of CO2 within the environment being supplemented with CO2.
S. Device according to any one of the preceding claims, characterized by the fact that the micro-controller and associated electronics (8) are used to control a dosing mechanism.
6. Device according to any one of the preceding claims characterized by the fact that it has at least one temperature sensor to measure the temperature of the space being supplemented with CO2.
7. Device according to any one of the preceding claims that has at least one light sensor for detecting when it is light and dark.
8. Device according to claim 7, characterized by the fact that it uses the information collected by the light sensor to adjust the CO2 setpoint accordingly.
9. Device according to claim 6, characterized by the fact that the CO2 setpoint is adjusted based on the temperature of the environment being supplemented with CO2.
10. Device according to any one of the preceding claims characterized by the fact that it has at least one screen to display the current level of CO2 and to display the CO2 setpoint and other data such as the temperature.
11. Device according to any one of the preceding claims characterized by the fact that it has at least one button (2), touch screen or control knob for adjusting the CO2 concentration set-point.
12. Device according to any one of the preceding claims characterized by the fact that that it transmits temperature and! or CO2 concentration levels to the cloud so that the data can be viewed on a device such as a PC or smart phone.
13. Device according to any one of the preceding claims characterized by the fact that it uses a fan (5) to disperse the CO2 throughout the environment.
14. Device according to any one of the preceding claims that utilizes an airlock (4) to prevent unwanted particles from entering the fermentation vessel and to indicate that fermentation is either active or inactive.
15. Device according to any one of the preceding claims that does not use a CO2 sensor but instead doses sugar into the fermenter at a rate decided upon by the user.
16. Device according to any one of the preceding claims that has a hose going from the outlet of the fermentation vessel to the top of the growing space.
17. A method for increasing and maintaining elevated CO2 levels in an enclosed space by means of a device that incrementally doses sugar or any sugar containing products into a fermentation vessel.