Field The present invention relates to a vessel, for example a vessel arrangeable in a substrate for receiving a gas released from the substrate.

Background to the invention Slatted units are a very prescriptive form of excrement storage that has long been associated with the bovine industry amongst others. These units are prescribed to have a storage time (retention time) of excrement so that farmers only spread excrement on the land at suitable times during the year as per the nitrates directive. Excrement stored in these units is not quickly absorbed by the soil as it is stored excrement rather than treated fertiliser. Bovine farming is very carbon intense and may in the near future come under the European carbon trading schemes making dairy products and beef more expensive. The primary reason why bovine farming is deemed carbon intense is that methane is released as excrement is decomposed and converted to fertiliser. Methane is circa 25 times more potent than C0 ₂ as a greenhouse gas and this factor is currently used in C0 ₂ equivalence calculations.

Anaerobic digestion (AD) is a form of treatment for excrement and biological waste that serves 2 primary functions: 1 ) the capturing of methane (CH ₄ ) emissions 2) the decomposition of the biological medium (substrate) into a high grade fertiliser that is absorbed circa 3 times quicker into plant life. Methane is then burnt in boilers and generators to provide heat and electricity to the agricultural facility. Most farms in Ireland and the UK are residential farms and therefore can use waste heat and electricity.

The primary reason why AD has not been invested in is due to capital costing. Viability studies have shown that in an Irish context, a size of a system would need to have a catchment area of circa 10 miles of agricultural land to support a viable size plant of circa 250kWe. While the viability studies do show promise, there is a fundamental problem with this approach being transport of excrement. For instance, a value of excrement would need to be significant to make it viable for a farmer to participate in the system. Furthermore if there were another outbreak of Foot and Mouth disease, for example, this whole market would be compromised as the biological culture used in a digester will die off quite quickly if it is not fed a constant feedstock. Note excrement transportation would be confined to a farm on the instance of an outbreak. Small modular on farm AD such as SEAB energy (UK) and portaferm (Germany) have been developed however the installation cost is circa £300k for a 20kWe unit as a separate digester and post treatment storage is required with such technologies. This is an unviable economic investment with a current payback in excess of 25 years in an Irish context.

Hence, there is a need to improve capturing gas released from a substrate, for example during AD of the substrate.

Summary of the Invention

It is one aim of the present invention, amongst others, to provide a vessel for receiving a gas released from a substrate which at least partially obviates or mitigates at least some of the disadvantages of the prior art, whether identified herein or elsewhere. For instance, it is an aim of embodiments of the invention to provide a vessel for receiving a gas released from a substrate that may reduce a cost of an apparatus for receiving the gas released from the substrate. For instance, it is an aim of embodiments of the invention to provide a vessel for receiving a gas released from a substrate that may be installed for existing substrate tanks (i.e. retrofitted). For instance, it is an aim of embodiments of the invention to provide a vessel for receiving a gas released from a substrate that may be modular, facilitating installation in substrate tanks of different sizes. For instance, it is an aim of embodiments of the invention to provide a vessel for receiving a gas released from a substrate that may promote AD of the substrate.

A first aspect of the invention provides a vessel arrangeable in a substrate for receiving a gas released from the substrate, the vessel comprising:

an inlet; and

a wall arranged to define a volume to receive the gas via the inlet;

wherein the vessel is buoyant in the substrate; and

wherein the vessel is coupleable to an adjacent vessel.

A second aspect of the invention provides a vessel assembly comprising:

a vessel according to the first aspect; and

means for coupling the vessel to a gas piping network.

A third aspect of the invention provides a method of receiving a gas released from a substrate using a vessel according to the first aspect or a vessel assembly according to the second aspect.

Detailed Description of the Invention According to the present invention there is provided a vessel for receiving a gas released from a substrate, as set forth in the appended claims. Also disclosed is a vessel assembly. Other features of the invention will be apparent from the dependent claims, and the description that follows.

Throughout this specification, the term "comprising" or "comprises" means including the component(s) specified but not to the exclusion of the presence of other components. The term "consisting essentially of or "consists essentially of" means including the components specified but excluding other components except for materials present as impurities, unavoidable materials present as a result of processes used to provide the components, and components added for a purpose other than achieving the technical effect of the invention, such as colourants, and the like.

The term "consisting of" or "consists of" means including the components specified but excluding other components.

Whenever appropriate, depending upon the context, the use of the term "comprises" or "comprising" may also be taken to include the meaning "consists essentially of" or "consisting essentially of", and also may also be taken to include the meaning "consists of" or "consisting of".

The optional features set out herein may be used either individually or in combination with each other where appropriate and particularly in the combinations as set out in the accompanying claims. The optional features for each aspect or exemplary embodiment of the invention, as set out herein are also applicable to all other aspects or exemplary embodiments of the invention, where appropriate. In other words, the skilled person reading this specification should consider the optional features for each aspect or exemplary embodiment of the invention as interchangeable and combinable between different aspects and exemplary embodiments.

The first aspect of the invention provides a vessel arrangeable in a substrate for receiving a gas released from the substrate, the vessel comprising:

an inlet; and

a wall arranged to define a volume to receive the gas via the inlet;

wherein the vessel is buoyant in the substrate; and

wherein the vessel is coupleable to an adjacent vessel.

It should be understood that the inlet is a gas inlet, through which the gas released from the substrate is received by the vessel. It should be understood that the substrate may comprise, for example, a liquid, a semi-liquid, a solid, and/or a suspended solid. For example, the substrate may comprise a slurry such as an organic slurry, excrement (also known as waste), animal excrement, livestock excrement and/or bovine excrement. The excrement may comprise faeces and/or urine, for example. The slurry may comprise, for example, feed and/or bedding. The substrate may comprise decomposed and/or partially decomposed excrement, such as aerobically and/or anaerobically digested and/or partially digested excrement. The slurry may comprise dried excrement, for example dried faeces. In an example embodiment, the substrate is a slurry. In an example embodiment, the substrate is a slurry comprising excrement.

It should be understood that the gas released from the substrate may comprise a hydrocarbon such as methane (CH ₄ ), carbon dioxide (C0 ₂ ), hydrogen sulphide (H ₂ S), ammonia (NH ₃ ), siloxanes, a contaminant. For example, the gas may comprise a biogas produced by anaerobic digestion of the substrate. In an example embodiment, the gas comprises a biogas. The gas released from the substrate may tend to be released as bubbles or microbubbles, that may tend to move upwards in and/or though the substrate, towards a surface of the substrate. Thus, the gas released from the substrate may be released from the surface of the substrate.

In this way, the vessel may be arranged in the substrate and gas released from the substrate may be received in the vessel via the inlet. For example, biogas produced by anaerobic digestion of excrement in a tank may be received in the vessel arranged in the substrate via the inlet. Subsequently, the biogas received in the vessel may be output from the vessel and combusted to provide heat and/or generate electricity, for example. In one example embodiment, the vessel is arrangeable partly in the substrate. In one example embodiment, the vessel is arrangeable partly on the substrate (i.e. the vessel is positively buoyant on the substrate). In one example embodiment, the vessel is arrangeable entirely in the substrate (i.e. the vessel is submersible in the substrate) In one example embodiment, the inlet is arrangeable in fluid communication with the substrate. In this way, gas released from the substrate may be received in the vessel via the inlet. In one example embodiment, the inlet is arrangeable in fluid communication with a surface of the substrate. In this way, gas released from the surface of the substrate may be received in the vessel via the inlet.

In an example embodiment, a size of the inlet is relatively large compared with a size of the vessel. For example, an area of the inlet in fluid communication with the surface of the substrate may be relatively large compared with a projected area of the vessel on the surface of the substrate. For example, the area of the inlet in fluid communication with the surface of the substrate may be >60%, >70%, >80%, >90%, >95%, >97.5% or >99% of the projected area of the vessel on the surface of the substrate. In this way, a fraction of the gas released from the surface and received by the vessel may be increased compared with another vessel having a relatively smaller inlet, thereby increasing an efficiency of receiving gas in the vessel via the inlet. In other words, it is preferred for substantially the whole (particularly the whole) of the surface of the substrate to be covered by the vessel(s), particularly to be covered by the area of the inlet(s) that are in fluid communication with the surface of the substrate.

In an example embodiment, the vessel comprises a guide arranged to tend to direct the gas released from the substrate towards the inlet. In an example embodiment, a size of the guide is relatively large compared with a size of the vessel. The guide may be arrangeable in fluid communication with the substrate and/or the surface of the substrate. For example, an area of the guide in fluid communication with the surface of the substrate may be relatively large compared with the projected area of the vessel on the surface of the substrate. For example, the area of the guide in fluid communication with the substrate and/or the surface of the substrate may be >60%, >70%, >80%, >90%, >95%, >97.5% or >99% of the projected area of the vessel on the surface of the substrate. In this way, a fraction of the gas released from the substrate and received by the vessel may be increased compared with another vessel having a relatively smaller guide, thereby increasing an efficiency of receiving gas in the vessel via the inlet.

In an example embodiment, a size of the inlet is relatively small compared with a size of the vessel and the vessel comprises a guide arranged to tend to direct the gas released from the substrate towards the inlet, as described above. The guide may provide additional buoyancy to the vessel in the substrate.

Since the vessel is buoyant in the substrate, the vessel may tend to float proximal the surface of the substrate. For example, a first part of the vessel maybe tend to be above the surface of the substrate and a second part of the vessel maybe tend to be below the surface of the substrate i.e. submerged or immersed in the substrate. The vessel may tend to float proximal the surface of the substrate while a level of the surface changes. For example, the level of the surface may tend to rise when additional substrate is added to a tank. For example, the level of the surface may tend to fall when the substrate is removed from the tank or as a result of anaerobic digestion of the substrate. In an example embodiment, the vessel is neutrally buoyant in the substrate. In an example embodiment, the vessel is positively buoyant in the substrate. In an example embodiment, the vessel is inherently buoyant in the substrate i.e. in an absence of any gas received in the vessel. In an example embodiment, the vessel is inherently neutrally buoyant in the substrate. In an example embodiment, the vessel is inherently positively buoyant in the substrate. In this way, the vessel may tend to float proximal a surface of excrement in a tank as excrement is added and/or removed from the tank.

Since the vessel is arrangeable in the substrate and receives the gas released from the substrate, a buoyancy of the vessel in use may change. For example, the buoyancy of the vessel may tend to increase due to the gas received in the vessel, such that the buoyancy of the vessel is increased. Conversely, the buoyancy of the vessel may tend to decrease when the gas or a part of the gas received in the vessel is output from the vessel, such that the buoyancy of the vessel is decreased. In this way, the vessel may tend to rise or fall in the substrate, respectively. For example, the second part of the vessel previously below the surface of the substrate may tend to rise or emerge above the surface of the substrate when the gas is received in the vessel. For example, the first part of the vessel previously above the surface of the substrate may tend to fall or submerge below the surface of the substrate when the gas or a part of the gas received in the vessel is output from the vessel. In this way, the vessel may tend to mix the substrate when the gas is received in and/or output from the vessel, by the vessel rising and/or falling in the substrate. Additionally and/or alternatively, by the vessel rising and/or falling in the substrate, substrate deposited on the vessel, for example, may tend to move from the vessel to on and/or in the substrate, for example on the surface of the substrate and/or below the surface of the substrate.

The gas received in the vessel may be at atmospheric pressure. Conversely, the gas received in the vessel may be at a positive pressure, relative to atmospheric pressure or at a negative pressure, relative to atmospheric pressure. If the gas received in the vessel is at atmospheric pressure, a level of the substrate in the inlet may be the same as the level of the substrate surrounding the vessel. If the gas received in the vessel is at the positive pressure, the level of the substrate in the inlet may be relatively lower than the level of the substrate surrounding the vessel. If the gas received in the vessel is at the negative pressure, the level of the substrate in the inlet may be relatively higher than the level of the substrate surrounding the vessel. As the pressure of the gas received in the vessel changes, the vessel may tend to rise and/or fall in the substrate. In this way, by the vessel rising and/or falling in the substrate, substrate deposited on the vessel, for example, may tend to move from the vessel to on and/or in the substrate, for example on the surface of the substrate and/or below the surface of the substrate.

Since the vessel is coupleable to an adjacent vessel, a plurality of vessels may be provided to cover a part or substantially a whole (particularly a whole) of the surface of the substrate. That is, the vessels may be modular and appropriate pluralities of vessels may be provided for use with tanks of different sizes, for example. In this way, a fraction of the gas released from the substrate and received by the vessels may be increased compared with a single vessel, thereby increasing an efficiency of receiving gas in the plurality of vessels. In addition, since the plurality of vessels may be coupled as described herein, additional substrate received on the vessels may move down between the overlapping walls of the vessels into the substrate below, while minimizing an amount of the gas released between the overlapping walls of the vessels, for example. Further, by covering a larger part and/or preferably substantially the whole (particularly the whole) of the surface of the substrate, anaerobic digestion of the substrate may be enhanced , for example, by reducing exposure of the substrate to oxygen in the air. In addition, safety may be increased since the vessel and/or plurality of vessels may better prevent immersion of an animal and/or person in the substrate.

In an example embodiment, the vessel is coupleable to an adjacent vessel whereby no linear gas path is defined between the coupled vessels. In this way, the gas released from the substrate may tend to be isolated from the air. In an example embodiment, the vessel comprises a coupling member arranged to couple the vessel to an adjacent vessel. For example, the vessel may comprise a coupling member arranged to couple the vessel to an adjacent vessel, whereby the wall of the vessel overlaps a wall of the adjacent vessel, defining an overlap region. In an example embodiment, the vessel is arranged to tend to direct the gas released from the substrate proximal the overlap region towards the inlet and/or towards an inlet of the adjacent vessel. In this way, an efficiency of receiving gas may be increased. In an example embodiment, the coupling member comprises a flexible and/or an extensible coupling member, for example, a rope, a chain, a resilient material, a reticulated material, a mesh, a flexible mesh, a herringbone mesh. In this way, the coupling member may accommodate relative movement of the vessel and the adjacent vessel. For example, the vessel may rise and/or fall relative to the adjacent vessel, as described herein. For example, additional substrate received on the vessel may move down between the overlapping walls into the substrate while minimizing an amount of the gas released between the overlapping walls. In an example embodiment, the vessel comprises a plurality of coupling members.

In an example embodiment, the vessel is arranged to interlace with an adjacent vessel. In an example embodiment, the vessel is arranged to interlock with an adjacent vessel.

The vessel comprises the wall arranged to define the volume to receive the gas via the inlet. In an example embodiment, the wall comprises an outer surface and an inner surface. The inner surface may be opposed to the outer surface. The wall may comprise a non-planar wall, a concave wall, a paraboloidal wall, a spheroidal wall, a spherical wall and/or a part thereof, arranged to define the volume to receive the gas via the inlet. In an example embodiment, the wall comprises a paraboloidal wall. In an example embodiment, the inlet is provided by an open side of the wall. For example, the inlet may be defined by a free edge of the wall. Additionally and/or alternatively, the inlet may be provided by the inner surface of the wall. In this way, the wall may isolate the substrate from air, for example, the wall may isolate the substrate from oxygen. In this way, anaerobic digestion of the substrate may be promoted, for example.

In an example embodiment, the wall comprises a plurality of wall portions, for example, 2, 3, 4, 5, 6 or more wall portions. For example, the wall may comprise a plurality of opposed side portions. In an example embodiment, the wall comprises a planar wall portion. In an example embodiment, the wall comprises a plurality of planar wall portions. In an example embodiment, the wall comprises a non-planar wall portion, for example an arcuate, convex or concave wall portion. In an example embodiment, the wall comprises a plurality of non-planar wall portions.

In an example embodiment, the wall comprises a pair of opposed, mutually-inclined side wall portions, defining a ridge, and a pair of opposed end wall portions.

In an example embodiment, the wall comprises a pair of opposed, mutually-inclined planar side wall portions, defining a ridge, and a pair of opposed end wall portions, wherein the wall portions are arranged to define a triangular prismatic volume to receive the gas. The inlet may be provided by an open, rectangular side of the wall, defined by free edges of the wall portions. Additionally and/or alternatively, the inlet may be provided by the inner surface of the wall.

In use, the vessel may be arranged in the substrate whereby the inlet for receiving the gas provided by the open side of the wall is in fluid communication with the surface of the substrate. In this way, an area of the inlet in fluid communication with the surface of the substrate may be relatively large compared with a projected area of the vessel on the surface of the substrate. Since a part of the side wall portions may be below the surface of the substrate, the gas released from the substrate that tends to move towards the surface of the substrate tends to be guided by an inner surface of these parts of the side wall portions, towards the volume to receive the gas. In this way, an amount of the gas received by the vessel may be increased, for example, optimizing or maximizing the amount of the gas received by the vessel. Since the side wall portions are inclined, additional substrate received on an outer surface of the wall may tend to move downwards towards the substrate.

In an example embodiment, the wall comprises a pair of opposed, mutually-inclined non-planar side wall portions, defining a ridge, and a pair of opposed end wall portions, wherein the wall portions are arranged to define the volume to receive the gas. The non-planar side wall portions may comprise side wall portions having convex outer surfaces. The non-planar side wall portions may comprise side wall portions having concave outer surfaces. The inlet may be provided by an open, rectangular side of the wall, defined by free edges of the wall portions. Additionally and/or alternatively, the inlet may be provided by the inner surface of the wall.

In other words, the wall may be arranged to reduce and/or minimize a surface area of the outer surface of the wall exposed to air above the surface of the substrate so as to reduce or avoid substrate from adhering to the wall. As described above, in use, the vessel may be arranged in the substrate whereby the inlet provided by the open side of the wall is in fluid communication with the surface of the substrate. In this way, an area of the inlet in fluid communication with the surface of the substrate may be relatively large compared with a projected area of the vessel on the surface of the substrate. Since a part of the side wall portions may be below the surface of the substrate, the gas released from the substrate that tends to move towards the surface of the substrate tends to be guided by an inner surface of these parts of the side wall portions, towards the volume. In this way, an amount of the gas received by the vessel may be increased , for example, optimizing or maximizing the amount of the gas received by the vessel. Since the side wall portions are inclined, additional substrate received on an outer surface of the wall may tend to move downwards towards the substrate. Furthermore, when the side wall portions have concave outer surfaces, parts of the side wall portions above the surface of the substrate may present a smaller effective area on which additional substrate may be received , thereby tending to reduce submersion of the vessel into the substrate due to a weight of the additional substrate received on the side wall portions.

In an example embodiment, the wall comprises a sheet, for example a sheet, a membrane or a film. In an example embodiment, the wall comprises a relatively inflexible wall, for example a relatively stiff or rigid sheet. In an example embodiment, the wall comprises a relatively flexible wall, for example a relatively flexible sheet. In an example embodiment, the wall comprises a member, for example a strut, a tie or a frame, arranged to reinforce the wall. In this way, a stiffness of the wall may be relatively increased. For example, the wall may comprise a relatively flexible sheet and a frame, arranged to reinforce the sheet.

In an example embodiment, the wall comprises an impermeable wall having no perforations therethrough. In this way, the gas received in the vessel may be stored in the vessel. In an example embodiment, the wall comprises a selectively permeable wall. In this way, for example, certain gases and/or liquids may be retained in the vessel by the wall while other gases and/or liquids may permeate and/or diffuse through the wall. In an example embodiment, the vessel comprises an outlet. In an example embodiment, the wall comprises an outlet comprising a perforation provided in the wall. The outlet may comprise a valve, arrangeable to isolate the gas received in the vessel. In this way, the gas received in the vessel may be output from the vessel via the outlet. In an example embodiment, the vessel comprises a plurality of outlets. In an example embodiment, the vessel comprises a single outlet.

In an example embodiment, the vessel comprises a plurality of inlets.

In an example embodiment, the vessel comprises a polymeric composition comprising a thermoplastic polymer. In an example embodiment, the wall comprises a polymeric composition comprising a thermoplastic polymer. The thermoplastic polymer may be a homopolymer or a copolymer.

Polymeric compositions comprising thermoplastics may be readily formed, for example by extrusion, moulding or injection moulding. Such polymeric compositions may have appropriate mechanical properties suitable for use in vessels. Such polymeric compositions may have appropriate chemical properties suitable for resistance to the environment. For example, such polymeric compositions may be resistant to chemicals, such as produced during anaerobic digestion. Such polymeric compositions may be of relatively low cost and/or environmental cost while providing sufficient longevity.

The thermoplastic polymer may be selected from a group consisting of poly(methyl methacrylate) (PMMA), acrylonitrile butadiene styrene (ABS), aliphatic or semi-aromatic polyamides, polylactic acid (polylactide) (PLA), polybenzimidazole (PBI), polycarbonate (PC), polyether sulfone (PES), polyetherimide, polyethylene (PE), polypropylene (PP), polymethylpentene (PMP) and polybutene-1 (PB-1 ), polystyrene (PS) and polyvinyl chloride (PVC).

The thermoplastic polymer may be a thermoplastic polyolefin. The thermoplastic polyolefin may be selected from a group consisting of: polyethylene (PE), polypropylene (PP), polymethylpentene (PMP) and polybutene-1 (PB-1 ).

The polyethylene may have a density range of 0.880-0.940 g/cm ³ . The polyethylene may have a density >0.940 g/cm ³ .

The polyethylene may be selected from a group consisting of high-density polyethylene (HDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), low- density polyethylene (LDPE) and very-low-density polyethylene (VLDPE). The polyethylene may have a crystallinity of more than 30%, more than 35%, more than 40%, more than 45%, more than 50%, more than 55%, more than 60%, more than 65%, more than 70%, more than 75%, more than 80%, more than 85%, more than 90%. The polymeric composition may comprise additives, such as fillers and/or colourants. The polymeric composition may be treated, for example, with a flame or fire retardant. In this way, the vessel may conform with industrial safety standards, such as BS5867 Part 2 Type C.

The polymeric composition may be treated, for example, with antimicrobial compositions, such as antifungal, antimildew and/or antibacterial compositions. In this way, a cleanliness or hygiene of the vessel may be increased.

The polymeric composition may be treated or coated, for example, to reduce a coefficient of friction of a surface of the sheet. In this way, additional substrate received on the surface of the sheet may tend to move or slide off the sheet.

In an example embodiment, the inner surface and/or the outer surface is untextured. For example, the outer surface may be smooth, without discernible texture. In this way, substrate received on the outer surface may more readily move off the wall. In an example embodiment, the inner surface and/or the outer surface is textured.

The sheet may have a mass per unit area in a range of 0.05 to 0.25 kgm ² , for example 0.1 1 kgm ² . The sheet may have a thickness in a range of 0.25 to 5.0 mm, for example 1.0 to 4.0 mm, such as 3.0 mm.

Sheets comprising a polymeric composition as described above may be coupled by adhesive coupling or welding, such as solvent or thermal welding, for example.

In an example embodiment, the sheet comprises a polypropylene sheet, having a mass per unit area of 2.7 kgm ^"2 .

In an example embodiment, the wall comprises a composite material, for example glass- reinforced plastic (GRP). In an example embodiment, the wall comprises a void, whereby a density of the wall is relatively decreased. In an example embodiment, the wall comprises a plurality of voids. In an example embodiment, the wall is hollow. In this way, a positive buoyancy of the vessel may be relatively increased. In an example embodiment, the vessel comprises a float, for example an auxiliary float, arranged to increase a positive buoyancy of the vessel. That is, the float may have a relatively higher positive buoyancy. The float may comprise a void and/or a plurality of voids. Additionally and/or alternatively, the float may comprise a hollow float. The float may be integral with the vessel, for example, a part of the wall. Additionally and/or alternatively, the float may be coupled to the wall, for example the float may be rigidly or flexibly coupled to the wall. The float may be arrangeable adjacent to the wall. The float may comprise a guide arranged to tend to direct the gas released from the substrate towards the inlet. For example, the float may comprise a convex guide arrangeable on the substrate. In this way, gas release from the substrate may tend to be guided laterally towards the inlet. A shape of the float may conform or pair or mate with a shape of the wall. A shape of the float may be similar to a shape of the wall, for example, an external shape and/or cross-sectional profile of the wall.

The second aspect of the invention provides a vessel assembly comprising:

a vessel according to the first aspect; and

means for coupling the vessel to a gas piping network.

In an example embodiment, the vessel assembly comprises a plurality of vessels. In particular, the vessel assembly may comprise a plurality of vessels so as to cover substantially the whole (particularly the whole) of the surface of the substrate.

In an example embodiment, the vessel assembly comprises a manifold arranged to couple the outlets of the plurality of vessels. In an example embodiment, the vessel assembly comprises a recirculation assembly. The recirculation assembly may comprise a pipe, a pump, a heat exchanger and/or a heater. In this way, the substrate may be mixed and/or heated by the recirculation assembly, thereby improving and/or promoting AD of the substrate. In turn, this may increase an amount of the gas released from the substrate.

In an example embodiment, the vessel assembly comprises a gas scrubber, arranged to scrub the gas. In this way, C0 ₂ and/or H ₂ S, for example, may be scrubbed from the gas prior to subsequent gas storage and/or burning. In an example embodiment, the vessel assembly comprises a gas storage tank for example to store the gas output from the vessel(s) prior to subsequent burning.

In an example embodiment, the vessel assembly comprises a tank, for example a substrate tank, a pit, a pond, a chamber. The third aspect of the invention provides a method of receiving a gas released from a substrate using a vessel according to the first aspect or a vessel assembly according to the second aspect. Brief description of the drawings

For a better understanding of the invention, and to show how exemplary embodiments of the same may be brought into effect, reference will be made, by way of example only, to the accompanying diagrammatic Figures, in which:

Figure 1 schematically depicts a cross-sectional view of a vessel according to an exemplary embodiment of the invention, in use;

Figure 2 schematically depicts a cross-sectional view of a vessel according to an exemplary embodiment of the invention, in use;

Figure 3 schematically depicts a cross-sectional view of a vessel according to an exemplary embodiment of the invention, in use; Figure 4 schematically depicts a cross-sectional view of a vessel according to an exemplary embodiment of the invention, in use;

Figure 5A & 5B schematically depicts a cross-sectional view of the vessel of Figure 4, in use; Figure 6 schematically depicts a cross-sectional view of a vessel assembly according to an exemplary embodiment of the invention, in use; and

Figure 7 schematically depicts rates of anaerobic digestion. Detailed Description of the Drawings

Figure 1 schematically depicts a cross-sectional view of a vessel 100 according to an exemplary embodiment of the invention, in use. Particularly, Figure 1 schematically depicts four (4) vessels 100A - 100D, in use. For clarity, reference numerals are provided for one vessel 100 only, specifically the vessel 100A.

The vessel 100 is arrangeable in a substrate 1 for receiving a gas 2 released from the substrate 1. The vessel comprises an inlet 1 10 and a wall 120 arranged to define a volume 130 to receive the gas via the inlet 1 10. The vessel 100 is buoyant in the substrate 1. The vessel 100 is coupleable to an adjacent vessel 100. In this way, gas released from the substrate may be received in the vessel, as described above.

In detail, the wall 120 comprises a sheet having an outer surface 121 and an inner surface 122. The inner surface 122 is opposed to the outer surface 121 . The wall 120 comprises a paraboloidal wall. The inlet 1 10 is provided by the inner surface 122 of the wall 120. In this way, the wall 120 may isolate the substrate 1 from air 3, for example, the wall 120 may isolate the substrate 1 from oxygen in the air 3. In this way, anaerobic digestion of the substrate 1 may be promoted.

In use, the vessel 100 is arranged in the substrate 1 whereby the inlet 1 10 is in fluid communication with a surface S of the substrate 1 . In this way, an area of the inlet 1 10 in fluid communication with the surface S of the substrate may be relatively large compared with a projected area of the vessel 100 on the surface S of the substrate 1.

The vessel 100 comprises a flexible coupling member (not shown) arranged to couple the vessel 100 to an adjacent vessel 100. Particularly, the vessel 100A is coupled to the adjacent vessel 100B, which is in turn coupled to the adjacent vessel 100C, which is in turn coupled to the adjacent vessel 100D. The vessel 100 comprises the coupling member arranged to couple the vessel to the adjacent vessel 100, whereby the wall 120 of the vessel 100 overlaps a wall 120 of the adjacent vessel 100, defining an overlap region 123. The vessel 100 is arranged to tend to direct the gas 2 released from the substrate 1 proximal the overlap region 123 towards the inlet 1 10. In this way, an efficiency of receiving gas may be increased. Since the vessel 100 is coupleable to an adjacent vessel 100, the plurality of vessels 100A - 100D may be provided to cover a part or substantially a whole (particularly a whole) of the surface S of the substrate 1. In this way, a fraction of the gas 2 released from the substrate 1 and received by the vessels 100A - 100D may be increased, for example compared with another arrangement in which the vessels cover less of the surface S of the substrate 1 , thereby increasing an efficiency of receiving gas 2 in the plurality of vessels 100A - 100D.

Figure 2 schematically depicts a cross-sectional view of a vessel 200 according to an exemplary embodiment of the invention, in use. Particularly, Figure 2 schematically depicts eight (8) vessels 200A - 200H, in use. For clarity, reference numerals are provided for one vessel 200 only, specifically the vessel 200A.

The vessel 200 is arrangeable in a substrate 1 for receiving a gas 2 released from the substrate 1. The vessel comprises an inlet 210 and a wall 220 arranged to define a volume 230 to receive the gas via the inlet 210. The vessel 200 is buoyant in the substrate 1. The vessel 200 is coupleable to an adjacent vessel 200. In this way, gas released from the substrate may be received in the vessel, as described above.

In detail, the wall 220 comprises a sheet having an outer surface 221 and an inner surface 222. The wall 220 comprises a pair of opposed, mutually-inclined non-planar side wall portions 224 & 225, defining a ridge 226, and a pair of opposed end wall portions (not shown), wherein the wall portions 224 & 225 are arranged to define the volume 223 to receive the gas 2. The non-planar side wall portions 224 & 225 comprise side wall portions having concave outer surfaces 221 . The inlet 210 is provided by the inner surface 222 of the wall 220. In this way, the wall 220 may isolate the substrate 1 from air 3, for example, the wall 220 may isolate the substrate 1 from oxygen in the air 3. In this way, anaerobic digestion of the substrate 1 may be promoted.

In use, the vessel 200 is arranged in the substrate 1 whereby the inlet 210 is in fluid communication with a surface S of the substrate 1 . In this way, an area of the inlet 210 in fluid communication with the surface S of the substrate may be relatively large compared with a projected area of the vessel 200 on the surface S of the substrate 1.

The vessel 200 comprises a flexible coupling member (not shown) arranged to couple the vessel 200 to an adjacent vessel 200. Particularly, the vessel 200A is coupled to the adjacent vessel 200B, which is in turn coupled to the adjacent vessel 200C, which is in turn coupled to the adjacent vessel 200D, etc. The vessel 200 comprises the coupling member arranged to couple the vessel to the adjacent vessel 200, whereby the wall 220 of the vessel 200 overlaps a wall 220 of the adjacent vessel 200, defining an overlap region 223. The vessel 200 is arranged to tend to direct the gas 2 released from the substrate 1 proximal the overlap region 223 towards the inlet 210. In this way, an efficiency of receiving gas may be increased.

Since the vessel 200 is coupleable to an adjacent vessel 200, the plurality of vessels 200A - 200H may be provided to cover a part or substantially a whole (particularly a whole) of the surface S of the substrate 1. In this way, a fraction of the gas 2 released from the substrate 1 and received by the vessels 200A -200H may be increased, for example compared with another arrangement in which the vessels cover less of the surface S of the substrate 1 , thereby increasing an efficiency of receiving gas 2 in the plurality of vessels 200A - 200H. Figure 3 schematically depicts a cross-sectional view of a vessel 300 according to an exemplary embodiment of the invention, in use. Particularly, Figure 3 schematically depicts four (4) vessels 300A - 300D, in use. For clarity, reference numerals are provided for one vessel 300 only, specifically the vessel 300A. The vessel 300 is arrangeable in a substrate 1 for receiving a gas 2 released from the substrate 1. The vessel comprises an inlet 310 and a wall 320 arranged to define a volume 330 to receive the gas via the inlet 310. The vessel 300 is buoyant in the substrate 1. The vessel 300 is coupleable to an adjacent vessel 300. In this way, the gas 2 released from the substrate 1 may be received in the vessel 300, as described above.

In detail, the wall 320 comprises a sheet having an outer surface 321 and an inner surface 322. The wall 320 comprises a pair of opposed, mutually-inclined planar side wall portions 324 & 325, defining a ridge 326, and a pair of opposed end wall portions (not shown), wherein the wall portions 324 & 325 are arranged to define the volume 330 to receive the gas 2. The inlet 310 is provided by the inner surface 322 of the wall 320. In this way, the wall 320 may isolate the substrate 1 from air 3, for example, the wall 320 may isolate the substrate 1 from oxygen in the air 3. In this way, anaerobic digestion of the substrate 1 may be promoted. In use, the vessel 300 is arranged in the substrate 1 whereby the inlet 310 is in fluid communication with a surface S of the substrate 1. In this way, an area of the inlet 310 in fluid communication with the surface S of the substrate may be relatively large compared with a projected area of the vessel 300 on the surface S of the substrate 1. The vessel 300 comprises a flexible coupling member (not shown) arranged to couple the vessel 300 to an adjacent vessel 300. Particularly, the vessel 300A is coupled to the adjacent vessel 300B, which is in turn coupled to the adjacent vessel 300C, which is in turn coupled to the adjacent vessel 300D. The vessel 300 comprises the coupling member arranged to couple the vessel to the adjacent vessel 300, whereby the wall 320 of the vessel 300 overlaps a wall 320 of the adjacent vessel 300, defining an overlap region 323. The vessel 300 is arranged to tend to direct the gas 2 released from the substrate 1 proximal the overlap region 323 towards the inlet 310. In this way, an efficiency of receiving gas may be increased.

Since the vessel 300 is coupleable to an adjacent vessel 300, the plurality of vessels 300A - 300D may be provided to cover a part or substantially a whole (particularly a whole) of the surface S of the substrate 1. In this way, a fraction of the gas 2 released from the substrate 1 and received by the vessels 300A - 300D may be increased, for example compared with another arrangement in which the vessels cover less of the surface S of the substrate 1 , thereby increasing an efficiency of receiving gas 2 in the plurality of vessels 300A - 300D.

Figure 4 schematically depicts a cross-sectional view of a vessel 400 according to an exemplary embodiment of the invention, in use. Particularly, Figure 4 schematically depicts three (3) vessels 400A - 400C, in use. For clarity, reference numerals are provided for one vessel 400 only, specifically the vessel 400A. The vessel 400 is arrangeable in a substrate 1 for receiving a gas 2 released from the substrate 1. The vessel comprises an inlet 410 and a wall 420 arranged to define a volume 330 to receive the gas via the inlet 410. The vessel 400 is buoyant in the substrate 1. The vessel 400 is coupleable to an adjacent vessel 400. In this way, the gas 2 released from the substrate 1 may be received in the vessel 400, as described above.

In detail, the wall 420 comprises a sheet having an outer surface 421 and an inner surface 422. The wall 420 comprises a pair of opposed, mutually-inclined planar side wall portions 424 & 425, defining a ridge 426, and a pair of opposed end wall portions (not shown), wherein the wall portions 424 & 425 are arranged to define the volume 423 to receive the gas 2. The inlet 410 is provided by the inner surface 422 of the wall 420. In this way, the wall 420 may isolate the substrate 1 from air 3, for example, the wall 420 may isolate the substrate 1 from oxygen in the air 3. In this way, anaerobic digestion of the substrate 1 may be promoted.

The vessel 400 comprises a float 430, for example an auxiliary float, arranged to increase a positive buoyancy of the vessel 400. The float 430 comprises a hollow float 430. The float 430 is flexibly coupled to the vessel 400. The float 430 is arrangeable adjacent to the wall 420. The float 430 comprises a convex guide 431 arranged to tend to direct gas released from the substrate 1 towards the inlet 410. In this way, gas 2 released from the substrate 1 may tend to be guided laterally towards the inlet 410. A shape of the float 430 is similar to a shape of the wall 410. Particularly, an external shape of the float 430 is similar to a shape of the wall 410 and/or a cross-sectional profile of the float 430 is similar to a cross-sectional profile of the wall 410.

The substrate 1 is received in a tank 5 having a slatted grid 6 provided across an open, top side of the tank. In use, additional substrate (not shown) is received through the slatted grid 6 and may be received on the vessel 400. In use, the vessel 400 is arranged in the substrate 1 whereby the inlet 410 is in fluid communication with a surface S of the substrate 1 . In this way, an area of the inlet 410 in fluid communication with the surface S of the substrate may be relatively large compared with a projected area of the vessel 400 on the surface S of the substrate 1. In use, the convex guide 431 of the float 430 is arranged on the surface S of the substrate 1. In this way, the float 430 may isolate the substrate 1 from air 3.

The vessel 400 comprises a flexible coupling member (not shown) arranged to couple the vessel 400 to an adjacent vessel 400. Particularly, the vessel 400A is coupled to the adjacent vessel 400B, which is in turn coupled to the adjacent vessel 400C. Specifically, the wall 420A is coupled to the float 430A, which is in turn coupled to the wall 420B, which is in turn coupled to the float 430B, which is in turn coupled to the wall 420C. The vessel 400 comprises the coupling member arranged to couple the vessel to the adjacent vessel 400, whereby the wall 420 of the vessel 400 overlaps a wall 420 of the adjacent vessel 400, defining an overlap region 423. Specifically, the wall 420A overlaps the float 430A, which is also overlapped by the wall 420B. Further, the wall 420B overlaps the float 430B, which is also overlapped by the wall 420C. The vessel 400 is arranged to tend to direct the gas 2 released from the substrate 1 proximal the overlap region 423 towards the inlet 410. In this way, an efficiency of receiving gas may be increased.

Since the vessel 400 is coupleable to an adjacent vessel 400, the plurality of vessels 400A - 400C may be provided to cover a part or substantially a whole (particularly a whole) of the surface S of the substrate 1. In this way, a fraction of the gas 2 released from the substrate 1 and received by the vessels 400A - 400C may be increased, for example compared with another arrangement in which the vessels cover less of the surface S of the substrate 1 , thereby increasing an efficiency of receiving gas 2 in the plurality of vessels 400A - 400C.

The vessel 400 comprises an outlet 440 (also known as a gas manifold pipe). In this way, the gas 2 received in the vessel 400 may be output from the vessel 400 via the outlet 440.

Figure 5A & 5B schematically depicts a cross-sectional view of the vessel of Figure 4, in use. Figure 5A schematically depicts a case when the gas 2 received in the vessel 400 is at a negative pressure, relative to atmospheric pressure. Figure 5B schematically depicts a case when the gas 2 received in the vessel 400 is at a positive pressure, relative to atmospheric pressure.

In detail, the gas 2 received in the vessel 400 may be at atmospheric pressure. Conversely, the gas 2 received in the vessel 400 may be at a positive pressure, relative to atmospheric pressure or at a negative pressure, relative to atmospheric pressure. If the gas received in the vessel 400 is at atmospheric pressure, a level of the substrate 1 in the inlet 410 may be the same as the level of the substrate 1 surrounding the vessel 400. If the gas 2 received in the vessel 400 is at the positive pressure, the level of the substrate 1 in the inlet 410 may be relatively lower than the level of the substrate 1 surrounding the vessel 400. If the gas 2 received in the vessel 400 is at the negative pressure, the level of the substrate 1 in the inlet 410 may be relatively higher than the level of the substrate 1 surrounding the vessel 400. As a pressure of the gas 2 received in the vessel 400 changes, the vessel 400 may tend to rise and/or fall in the substrate 1. In this way, by the vessel 400 rising and/or falling in the substrate 1 , additional substrate 1 deposited on the vessel 400, for example, may tend to move from the vessel 400 to on and/or in the substrate 1 , for example on the surface S of the substrate 1 and/or below the surface S of the substrate 1.

Since the vessel 400 is flexibly coupled to an adjacent vessel, the coupling member may accommodate relative movement of the vessel and the adjacent vessel. For example, the vessel may rise and/or fall relative to the adjacent vessel, as described above. For example, additional substrate received on the vessel may move down between the overlapping walls into the substrate while minimizing an amount of the gas released between the overlapping walls.

Figure 6 schematically depicts a cross-sectional view of a vessel assembly 1000 according to an exemplary embodiment of the invention, in use. Particularly, Figure 6 schematically depicts the vessel assembly 1000 comprising the three (3) vessels 400A - 400C, as described above.

The substrate 1 (i.e. slurry comprising excrement) is received in the tank 5 having the slatted grid 6 provided across an open, top side of the tank. In use, additional substrate 1 ' (i.e. excrement) is received through the slatted grid 6 from a cow 7 and may be received on the vessel 400. The vessels 400A - 400C are arranged to cover substantially the surface S of the substrate 1 , for example the entire surface S of the substrate 1 , thereby increasing an amount of the gas 2 received in the vessel 400A - 400C via the inlets 41 OA - 410C respectively. By covering substantially the surface S of the substrate 1 , AD of the substrate 1 may be improved and/or promoted. By covering substantially the surface S of the substrate 1 , drying of the substrate 1 may be reduced, thereby improving and/or promoting AD of the substrate 1.

The outlets 440A - 440C of the vessels 400A - 400C respectively are coupled via a manifold (not shown) to an outlet pipe (not shown) (i.e. means for coupling the vessel to a gas piping network). In this way, the gas 2 received in the vessels 400A - 400C may be communicated, for example exhausted, pumped, to a boiler and/or generator to provide heat and/or electricity, respectively. The vessel assembly may be arranged whereby the gas 2 is pumped when a pressure of the gas reaches a threshold pressure and/or a level of the vessel rises to a predetermined height. The vessel assembly 1000 further comprises a recirculation assembly 1 100 communicatively coupled to a base of the tank 5 and to a side of the tank 5, below the surface S of the substrate 1. The recirculation assembly 1 100 comprises a pump 1 101 , arranged to pump the substrate 1 , and a heater 1 102, arranged to heat the pumped substrate. In this way, the substrate 1 may be mixed and/or heated by the recirculation assembly 1 100, thereby improving and/or promoting AD of the substrate 1 . In turn, this may increase an amount of the gas 2 released from the substrate 1.

Figure 7 schematically depicts rates of anaerobic digestion for different anaerobic organisms.

Anaerobic Digestion (AD) is a form of treatment for excrement and biological waste that serves 2 primary functions 1 ) the capturing of methane (CH4) emissions 2) the decomposition of the biological medium (substrate) into a high grade fertiliser that is absorbed circa 3 times quicker into plant life.

Different AD technologies use different anaerobic organisms all that work at different retention times and this generally converts as follows higher retention times means lower storage temperature, as shown in Table 1 and Figure 7.

Table 1 : Temperatures and retention times for different anaerobic organisms.

Consider a slatted unit that fills linearly from day 1 to day 100 also the temperature is in the psychrophillic range typically even in winter 10-15 degrees due to the internal heating effect of excrement. This implies that psychrophilic technologies are more applicable in this instance than the tried and tested messophillic digesters. Psychrophillic digesters are usually covered lagoons i.e. a floating membrane over a pond of excrement. However slatted units drop excrement from a height and any membrane for this purpose must allow excrement to pass down while trapping methane as it rises below.

Although a preferred embodiment has been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims and as described above.

In summary, the invention provides a vessel arrangeable in a substrate, for example slurry or excrement, for receiving a gas, for example biogas, released from the substrate. The vessel comprises an inlet and a wall arranged to define a volume to receive the gas via the inlet. The vessel is buoyant in the substrate. The vessel is coupleable to an adjacent vessel. In this way, gas released from the substrate may be received in the vessel, as described above. In this way, a cost may be reduced. In this way, the vessel may be installed for existing substrate tanks (i.e. retrofitted). In this way, additional and/or ancillary tanks may not be required. In this way, the vessel may be modular, facilitating installation in substrate tanks of different sizes. In this way, the vessel may promote AD of the substrate.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.