GB2621138A

GB2621138A - Insect production process using carbon capture

Info

Publication number: GB2621138A
Application number: GB2211220.5A
Authority: GB
Inventors: C Peters Evelyn; Rajiyah Anushka; Banks Dylan; Mozzanega Philippe
Original assignee: Future By Insects Ltd
Current assignee: Future By Insects Ltd
Priority date: 2022-08-02
Filing date: 2022-08-02
Publication date: 2024-02-07
Also published as: GB202211220D0; WO2024028407A1

Abstract

A production method for insect feed comprises passing a gas stream containing carbon dioxide into an aqueous algae solution, harvesting the algae, and processing it to produce insect feed 5-8. The carbon dioxide may be captured from an industrial plant 1 such as a food processing plant. The gas stream may be cooled to a temperature ≤ 50°C before passing it into the solution; this may be done using a heat exchanger 3a/b, including a water-cooling coil, the water from the water-cooling coil may be used to heat the solution to temperature ≤ 28°C. A system for producing algae is also claimed comprising a diversion valve to divert the gas stream, via a gas channel, from an industrial plant to a photobioreactor containing the aqueous algae solution. The photobioreactor may be a high-rate algal pond 4. The algae may comprise Chlorophyta sorokiniana, Scenedesmus obliquus and/or Schizochytrium sp. The produced insect feed may be added to an insect bioreactor 9, optionally containing black soldier flies; ammonia may be separated from the air in the bioreactor; and then added to the aqueous algae solution. Insects may be harvested from the bioreactor and used for animal feed, insect meal, fertilizer, lipids and/or chitin.

Description

INSECT PRODUCTION PROCESS USING CARBON CAPTURE

FIELD OF THE INVENTION

The invention relates to a process for insect production using carbon capture and sequestration, primarily but not exclusively for use in producing animal feed. The invention also relates to apparatus for performing the process.

BACKGROUND

Processes and technologies that capture and sequester CO2 emissions are a major subject of ongoing research. The CO2 emitted by combustion and industrial activities, mainly plant flue gas, is a significant single source of greenhouse gas emissions. It is desirable to capture CO2 released from such sources to reduce overall CO2 emissions and the resulting climate change.

Existing technologies provide 'end of pipe' CO2 removal. One example is quad-generation, which provides a combination of electricity, heating, cooling and carbon dioxide from the exhaust gas. These outputs come at significant infrastructure and energy efficiency costs, which works for business models that require high-quality and food-grade CO2, such as the carbonated drinks and food industries.

With these processes, CO2 is scrubbed and can be used in industrial processes. The technology also offers the potential for carbon sequestration through follow-on usage of the CO2.

The majority of modern carbon capture and sequestration technologies use a two-step process. To begin, a technology for isolating CO2 from flue gas or other gaseous emission sources is sought. After the CO2 is isolated it then needs to be captured and stored.

CO2 can be captured in a variety of ways, including by using liquid solvents, solid zeolite, and various membranes. However, without releasing CO2 into the atmosphere, the capture media must be regenerated, which is challenging to perform in traditional physical separation procedures.

CO2 gas or liquid is typically sequestered by being injected into subsurface geological formations or deep ocean levels. However, for CO2 disposal, highly precise geological configurations are required, which are not usually present at CO2 emission locations. As a result, transportation adds a significant amount of money and effort to the overall process. Furthermore, whether CO2 can be permanently sequestered underground is unknown. The two-step process is also inefficient since CO2 makes up a small fraction of a much larger volume of flue gas, and treating such a large flow stream to recover a small portion of it as CO2 is inefficient and costly.

Chemical absorption using liquids such as amines or aqueous solutions of bases, physical absorption in an appropriate solution, and membrane separation are all options for CO2 capture. All of these approaches have the issue of having to replenish the absorption media without losing CO2. Physical adsorption and cryogenic separation, for example, both need considerable quantities of energy in the form of heat or pressure.

Many researchers are looking at techniques for capturing and sequestering CO2 from the atmosphere. These techniques are not suited for CO2 emissions from industrial plants such as food processors due to the significant CO2 concentration differential between ambient air and flue or exhaust gas from such plants. CO2 concentrations in ambient air are typically between 0.03 and 0.04 percent, but CO2 concentrations in industrial waste gas are typically 3.0 percent or higher.

Another major environmental issue facing modern society is the emission of carbon dioxide and other waste products from protein production. Low-carbon and sustainable protein production is one of the most complex and challenging aspects of Net-Zero food sustainability and carbon dioxide emissions reductions.

The invention addresses the above problems by providing a method of protein production having a zero-carbon footprint, which incorporates carbon capture and sequestration.

SUMMARY

According to an aspect of the invention, there is provided a method for producing insect feed comprising: passing a gas stream containing CO2 into a solution containing water and algae, harvesting algae from the solution, and processing the harvested algae to produce insect feed.

The method of the invention takes CO2 captured from the waste gas and directly uses it to produce organic matter in the form of algae. This fixes the carbon from the gas in a solid and usable form, and is less energy intensive than many alternative carbon capture techniques. By using the algae as food for insects, the invention converts the captured carbon into a useful product in a continuous process, again without requiring significant energy input. The insects produced provide source of protein suitable for use by the food industry, in particular as a component of animal feed. In this way, the waste gas carbon is captured and passed back into the food chain efficiently.

Preferably, the method further comprises a first step of diverting the gas stream using a diversion valve.

Preferably, the step of passing the gas stream into the solution is performed in a photobioreactor.

Preferably, the photobioreactor is a high-rate algal pond (HRAP).

Preferably, the step of passing the gas stream into the solution is a continuous algal production process.

Preferably, the method further comprises a step of cooling the gas stream to a temperature of 50 °C or less before the step of passing the gas stream into the solution.

Preferably, the cooling step is performed using a heat exchanger including a water-cooling coil, the method further comprising passing water heated in the water-cooling coil during the cooling step into the solution so as to heat the solution.

Preferably, the method further comprises connecting the water-cooling coil to a source of industrial waste water.

Preferably, the method further comprises controlling the amount of heated water passed into the solution so as to maintain the temperature of the solution at 28 °C or less.

Preferably, the step of passing the gas stream into the solution comprises bubbling the gas stream through a bubble generator and a diffuser into the solution.

Preferably, the harvesting step comprises one or more of skimming, draining and settling of the algae from the solution.

Preferably, the processing step comprises allowing the harvested algae to settle and drain in a settling tank.

Preferably, the processing step comprises mixing the harvested algae with food waste.

Preferably, the method further comprises supplying the produced insect feed to an insect bioreactor.

Preferably, the method further comprises separating ammonia from air in the insect bioreactor and adding the separated ammonia to the solution containing water and algae.

Preferably, the insect bioreactor contains black soldier flies.

Preferably, the cooling step is performed using at least one heat exchanger including a water-cooling coil, further comprising passing water heated in the water-cooling coil during the cooling step to the insect bioreactor so as to heat the insect bioreactor.

Preferably, the method further comprises harvesting insects from the insect bioreactor and processing the harvested insects to produce at least one of animal feed, insect meal, fertilizer, lipids and chitin.

Preferably, the algae comprises one or more species selected from the group consisting of: Chlorophyta sorokiniana, Scenedesmus obliquus and Schizochytrium sp.

According to another aspect of the invention, there is provided a system for producing algae comprising: a diversion valve connectable to a gas outlet of an industrial plant so as to divert a gas stream from the industrial plant, a photobioreactor containing a solution containing water and algae, and a gas channel fluidly connecting the diversion valve and the photobioreactor, wherein the gas channel is configured to pass the diverted gas stream into the solution contained in the photobioreactor.

Preferably, the system further comprises a bubble generator connected to an outlet end of the gas channel and configured to bubble the diverted gas stream into the solution.

Preferably, the system further comprises a diffuser connected to the bubble generator.

Preferably, the system further comprises a first heat exchanger connected between the diversion valve and the gas channel, the first heat exchanger being configured to cool the diverted gas stream.

Preferably, the first heat exchanger comprises a water-cooling coil and the water-cooling coil is fluidly connected to the photobioreactor such that heated water from the water-cooling coil flows into the solution of the photobioreactor.

Preferably, the system further comprises an insect bioreactor.

Preferably, the insect bioreactor comprises a scrubber for separating ammonia from air in the insect bioreactor.

Preferably, the system further comprises: a second heat exchanger connected between the diversion valve and the photobioreactor in parallel with the first heat exchanger, the second heat exchanger being configured to cool the diverted gas stream, and an auxiliary gas channel configured to pass the cooled gas stream from the second heat exchanger into the solution contained in the photobioreactor, wherein the second heat exchanger comprises a water-cooling coil and wherein the water-cooling coil is fluidly connected to the insect bioreactor such that heated water from the water-cooling coil heats the insect bioreactor.

Insect-derived products of the kind produced by the invention can be paired with other protein sources, such as pulses and legumes as an alternative to soy-based feed. This will allow food industries such as the animal feed industry to reduce soya intake while boosting net-zero goals by improving the market demand for local pulses, which in turn reduce nitrogen usage and carbon emissions. In addition, the frass of the insects produced by the invention may have significant value as an alternative to chemical fertilizers. Another product of the invention is chitin, which is a naturally occurring compound from the polysaccharide group.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way of further example only and with reference to the accompanying drawings, in which: Fig. 1 shows a system for insect production using carbon capture according to an embodiment of the invention.

DETAILED DESCRIPTION

The present invention alleviates to a great extent the disadvantages of known carbon capture and sequestration methods by providing a direct route by which carbon dioxide in plant gas flumes can be captured into algae and sequestered into food and materials supply chains.

Industrial plant flue or exhaust gas often contains significant amounts of CO2. As a brief overview, the invention includes capturing that CO2, passing it through a water tank in which algae is being grown so as to increase the algal growth, and then using the resulting algae as a food source for insects. The insects produced by the invention provide a source of protein, typically used in animal feed.

A system for performing the method of the invention is shown in Fig. 1. The system includes a source of CO2, typically a gas stream from an industrial plant. In a preferred embodiment, the industrial plant is a food processing plant. The system also optionally includes a filtering device connected to the source of CO2, which is a gas filter for removing pollutants such as sulphur dioxide and carbon monoxide from the gas stream.

The gas filter is connected to two heat exchangers, which each receive part of the filtered gas and cool it. A first one of the heat exchangers is connected to a source of factory process discharge water, which is cooler than the filtered gas stream. The heat exchanger brings the discharge water into thermal contact with the gas stream using a water cooling coil for example, which cools the gas stream and heats the water.

The first heat exchanger is fluidly connected to algae growth ponds, also known as raceway ponds. The heated water is supplied to the ponds to heat the water in which the algae are grown via one fluid connection. Another fluid connection supplies the cooled gas containing CO2 to the pond water via a bubble generator and a diffuser, which increases the CO2 content of the water in which the algae is grown. This produces algae biomass, capturing the carbon from the gas stream.

In a preferred embodiment the carbon capture system is connected to a food processing plant. In this case the water used by the first heat exchanger is food processing wastewater (FPW) from the plant. This wastewater contains organic matter and enhances the growth of microorganisms, which causes eutrophication of freshwater bodies if the wastewater is discharged without treatment. FPW does not contain toxic metals such as heavy metals and is non-toxic compared with other industrial effluents. FPW is characterized by high organic content in the form of total dissolved solids (TDS), total suspended solids (TSS), oils, fats, and grease. The FPW typically also has high biological oxygen demand (BOD) and chemical oxygen demand (COD).

The microalgae used in the algae growth ponds connected to the first heat exchanger are highly efficient in removing nitrogen and phosphorus from the wastewater even at very low concentrations. The algae also reduce TDS, TSS, BOD and COD in the FPW supplied to the ponds. This makes the algae growth ponds an environmentally friendly tertiary wastewater treatment to facilitate compliance with regulations concerning effluent release from a food processing plant, while at the same time removing micropollutants and pathogens.

The second one of the heat exchangers is connected to a source of fresh water, which is brought into thermal contact with the other part of the filtered gas stream so as to heat the water and cool the gas. The cooled gas is supplied to the algae growth ponds through a fluid connection. The cooled gas is supplied to the pond water via a bubble generator and a diffuser. The heated water from the heat exchanger is supplied via another fluid connection to an insect bioreactor so as to heat the bioreactor.

Another input to the insect bioreactor is the algae biomass from the algae growth ponds, which provides food for the insects. Suitable insects for the bioreactor include black soldier flies. The insects produced by the bioreactor are harvested and processed for use in various industries such as the animal feed industry.

The insect bioreactor also generates ammonia, which can be separated from the air of the bioreactor. The separation process can comprise directly dissolving the ammonia into a liquid, preferably water, or using a scrubber. The ammonia extracted from the insect bioreactor is preferably fed back into the system by adding the ammonia to the water of the photobioreactor. The added ammonia boosts algae growth and quality in the photobioreactor.

One embodiment of the process of the invention utilises plant waste gas CO2 for the production of insect feed using the following steps: 1. Diverting all, or a proportion of the gas stream (CO2 and other gases) from an industrial plant using known methods.

2. Extracting any gases that are directly or indirectly harmful to the production of algae, such as sulphur dioxide, as well as any organic matter and soot or ash. This may be performed using a known filtering device.

3. If necessary, cooling the gas to a temperature that is suitable for the growth of algae. The maximum temperature of the gas for algae production is SO degrees Celsius. The cooling step can be performed using a water cooling coil or another known cooling device. The water cooling coil may also be used to heat the water within which the algae is grown, should that be necessary. The water in which the algae is grown has a maximum temperature of 28 degrees Celsius.

Preferably, the water used in the water cooling system is derived from by-products of factory processes.

4. Bubbling the diverted gas after extraction and cooling through a bubble generator and diffuser into a solution containing algae and appropriate nutrients to promote algae growth. This step results in the production of algae at a higher rate than would be possible without using the diverted gas.

Preferably the water in which the algae are grown is by-product water from factory processes. The algae solution may be contained in one or more open or covered ponds, forming an algae growth plant. Artificial light may be used to assist the algae growth process.

The algae remove pollutants from the wastewater in the pond so that the water can be discharged into inland water sources or used for irrigation.

5. Continuously harvesting the algae for processing. Harvesting can be undertaken by various known methods, including skimming, draining or settling of the algae from the growth solution.

6. Optionally processing the harvested algae in preparation for use as an insect feed substrate, ensuring that an appropriate amount of water remains in the algae. This step is omitted in some embodiments in which the harvested algae is ready to be mixed with other ingredients to form insect feed. The processing step may also simply consist of draining the algae. As an alternative, the algae can be spray-dried for long term storage and then rehydrated for use at a later date.

7. Producing insect feed from the algae by combining the harvested and optionally processed algae with other known feed sources that meet the appropriate nutritional and moisture requirements for insect feed production.

For example, the algae can be combined with organic waste output from a food processor to produce insect feed with higher protein, which improves growth of the insects. The food processor can be the same food processing plant that supplies the gas stream for the preceding gas diversion and extraction steps.

The insect feed produced by the above method can be supplied to a known insect bioreactor. The inventors have found that black soldier flies are particularly suitable as the insects fed using the processed algae. Any excess heated water from the cooling step described above may be used for the heating of the insect bioreactor.

Insects grown in the bioreactor can then be harvested and used to produce animal feed, for example by combining the insects as a source of protein with pulses or other animal food ingredients. The insects can also be used to produce other useful products including fertilizer, lipids and chitin. For example, insect larvae can be processed into insect lipids and insect meal, and the production of insects will generate frass, which can be used as fertilizer.

The gas diversion step can be performed using a diversion valve that is integrated into a modified wet-scrubber technology, which is connected to the boiler of a food processing plant or other industrial plant in the typical fashion. The diversion valve can be fitted at the outlet site of the wet-scrubber, ensuring the connecting and retro-fitting of the diversion valve is straightforward and cost effective. Integrating the gas diversion step at this point ensures that the technology: a. can be retro-fitted, and b. does not affect output and operating pressures within the boiler.

The step of extracting harmful gases can be performed using known wet-scrubber technologies, which are typically used for cleaning air, fuel gas or other gases of various pollutants and dust particles. Wet scrubbing works via the contact of target compounds or particulate matter with the scrubbing solution. Solutions may simply be water (for dust) or solutions of reagents that specifically target certain compounds, such as limestone for sulphur dioxide.

Various species of algae and preferably microalgae can be used to provide the algae growth for the bubbling and harvesting steps. Examples of suitable microalgae species include the following options: a. An oil-rich freshwater Chlorophyta, Chlorella sorokiniana. C. sorokiniana divides rapidly and accumulates up to 60% dry weight (dw) of oil relative to the total dry weight of the algae.

b. A protein-rich freshwater Chlorophyta, Scenedesmus obliquus (also classified as Tetradesmus obliquus). S. obliquus accumulates up to 45% dw of proteins relative to the total dry weight of the algae.

c. A DHA-rich freshwater algae, Schizochytrium sp. Schizochytrium is a rich source of docosahexaenoic acid, DHA (66%-lipid with 27%-DHA relative to the total dry weight of the algae).

The microalgae growth preferably takes place in a photobioreactor of any suitable shape, for example a high-rate algal pond (HRAP). Additional/supplemental artificial lighting can be provided, internally or externally. If a HRAP is used, it can be covered or uncovered. The photobioreactor, preferably HRAP, is typically equipped with gas bubbling mating or other gas infusing technology.

The microalgae production of the invention is preferably installed at the end process of a co-located industry providing CO2 waste gas such as exhaust or flue gas, for example a food processing plant or manufacturing facility.

The microalgae culture production preferably used in the algae growth step can be continuous, substantially-continuous or semi-continuous (e.g. a fill and draw type process). The algae biomass is harvested according to the type of production process used, ready for processing before use as a feed substrate for insects for example. Maintaining a 'continuous' culture production process has benefits in that the biomass can be harvested whilst maintaining a high optical density of active culture in the photobioreactor, thus providing high throughput and using the available light more efficiently.

Parameters such as biomass growth rate and cell count can be monitored during the algae growth process and used to adjust control parameters of the process such as gas supply rate, gas temperature and water temperature.

The algae harvesting step can be undertaken by skimming or draining or passive settling of the algae from the growth reactor into a settling tank. Appropriate harvesting methods include low-energy dynamic settling and the use of known low energy separation technology.

The foregoing description has been given by way of example only and it will be appreciated by a person skilled in the art that modifications can be made without departing from the scope of the present invention as defined by the claims.

Claims

CLAIMS1. A method for producing insect feed comprising: passing a gas stream containing CO2 into a solution containing water and algae; harvesting algae from the solution; and processing the harvested algae to produce insect feed.
2. The method of claim 1, further comprising a first step of diverting the gas stream using a diversion valve.
3. The method of claim 1 or claim 2, wherein the step of passing the gas stream into the solution is performed in a photobioreactor.
4. The method of claim 3, wherein the photobioreactor is a high-rate algal pond (H RAP).
S. The method of any preceding claim, wherein the step of passing the gas stream into the solution is a continuous algal production process.
6. The method of any preceding claim, further comprising a step of cooling the gas stream to a temperature of 50 °C or less before the step of passing the gas stream into the solution.
7. The method of claim 6, wherein the cooling step is performed using a heat exchanger including a water-cooling coil, the method further comprising passing water heated in the water-cooling coil during the cooling step into the solution so as to heat the solution.
8. The method of claim 7, further comprising connecting the water-cooling coil to a source of industrial waste water.
9. The method of claim 7 or claim 8, comprising controlling the amount of heated water passed into the solution so as to maintain the temperature of the solution at 28 °C or less.
10. The method of any preceding claim, wherein the step of passing the gas stream into the solution comprises bubbling the gas stream through a bubble generator and a diffuser into the solution.
11. The method of any preceding claim, wherein the harvesting step comprises one or more of skimming, draining and settling of the algae from the solution.
12. The method of any preceding claim, wherein the processing step comprises mixing the harvested algae with food waste.
13. The method of any preceding claim, further comprising supplying the produced insect feed to an insect bioreactor.
14. The method of claim 13, further comprising separating ammonia from air in the insect bioreactor and adding the separated ammonia to the solution containing water and algae.
15. The method of claim 13 or claim 14, wherein the insect bioreactor contains black soldier flies.
16. The method of one of claims 13-15, wherein the cooling step is performed using at least one heat exchanger including a water-cooling coil, further comprising passing water heated in the water-cooling coil during the cooling step to the insect bioreactor so as to heat the insect bioreactor.
17. The method of any of claims 13-16, further comprising harvesting insects from the insect bioreactor and processing the harvested insects to produce at least one of animal feed, insect meal, fertilizer, lipids and chitin.
18. The method of any preceding claim, wherein the algae comprises one or more species selected from the group consisting of: Chlorophyta sorokiniana, Scenedesmus obliquus and Schizochytrium sp.
19. A system for producing algae comprising: a diversion valve connectable to a gas outlet of an industrial plant so as to divert a gas stream from the industrial plant; a photobioreactor containing a solution containing water and algae; and a gas channel fluidly connecting the diversion valve and the photobioreactor, wherein the gas channel is configured to pass the diverted gas stream into the solution contained in the photobioreactor.
20. The system of claim 19, further comprising a bubble generator connected to an outlet end of the gas channel and configured to bubble the diverted gas stream into the solution.
21. The system of claim 20, further comprising a diffuser connected to the bubble generator.
22. The system of any of claims 19-21, further comprising a first heat exchanger connected between the diversion valve and the gas channel, the first heat exchanger being configured to cool the diverted gas stream.
23. The system of claim 22, wherein the first heat exchanger comprises a water-cooling coil and wherein the water-cooling coil is fluidly connected to the photobioreactor such that heated water from the water-cooling coil flows into the solution of the photobioreactor.
24. The system of any of claims 19-23, further comprising an insect bioreactor.
25. The system of claim 24, wherein the insect bioreactor comprises a scrubber for separating ammonia from air in the insect bioreactor.
26. The system of one of claims 24-25 as dependent on claim 23, further comprising: a second heat exchanger connected between the diversion valve and the photobioreactor in parallel with the first heat exchanger, the second heat exchanger being configured to cool the diverted gas stream, and an auxiliary gas channel configured to pass the cooled gas stream from the second heat exchanger into the solution contained in the photobioreactor, wherein the second heat exchanger comprises a water-cooling coil and wherein the water-cooling coil is fluidly connected to the insect bioreactor such that heated water from the water-cooling coil heats the insect bioreactor.