System and method for controlling and regulating the energy supplied to a fish farming facility

Abstract

A method and a system for controlling energy for a fish farming facility are described, where the facility comprises at least one sealed vessel with water and at least two energy sources, where an energy source such as a solar panel is arranged for cooling or heating the water in the vessel.

Description

[0001] Field of the Invention

[0002] The present invention relates to a system and a method for controlling and regulating the energy supplied to an aquaculture facility.

[0003] Background of the Invention

[0004] Given the environmental challenges currently associated with the farming of marine species in open sea cages, more and more production must take place in closed tanks. The demand for increased production and profitability means the tanks are becoming larger, and to maximize their utilization, fish must be transferred from one tank to another as the fish or marine organisms grow.

[0005] Significant amounts of energy are required to operate such an aquaculture facility, and methods are being sought to reduce energy consumption. Furthermore, methods are being sought that allow energy sources unable to deliver energy consistently over a period of time to be used.

[0006] Objects of the Invention

[0007] The aim of the present invention is to reduce energy demand in an aquaculture facility. Preferably, the aquaculture facility is a Recirculating Aquaculture System (RAS) facility.

[0008] Additionally, the invention aims to utilize a large water reservoir (as in an aquaculture facility) to absorb energy from, for example, a solar power system without the water temperature in the facility fluctuating beyond what is tolerable for the fish. The invention aims for changes in temperature over a day of + / - 0.1-0.3 degrees Celsius. Cooling is often required due to heat generated by the metabolism of the fish and the biofilter. A solar panel (an intermittent energy source) would provide significant energy during the day but little at night. The water can act as an accumulator to even out these fluctuations.

[0009] Summary of the Invention

[0010] In a first aspect, the present invention relates to a method for controlling energy in an aquaculture facility, characterized in that the facility comprises at least one closed tank with water and at least two energy sources. A first energy source, providing consistent energy, is mainly intended to supply energy to pumps, fans, control systems, and lights. A second energy source, providing intermittent energy, is intended for cooling or heating the water in the tank via a heat pump. This heat pump adjusts the cooling or heating to keep the water temperature above a predetermined lower temperature T1 and below an upper predetermined temperature T2.

[0011] In one embodiment, marine organisms in the aquaculture facility generate variable energy through heterotrophic activity, influenced by the amount of feed and oxygen supplied.

[0012] In another embodiment, energy input to the tank is adjusted based on the amount of variable energy produced by heterotrophic activity in the tank.

[0013] By calculating the amount of feed added to the aquaculture facility and the oxygen levels in the water, the contribution of heterotrophic energy to the energy balance of the aquaculture facility can be determined, enabling adjustments to the energy supply from the two energy sources.

[0014] In one embodiment, the second energy source is a solar power system. In another, the first energy source is the power grid. In another, the first energy source has a backup in the form of a generator. In another, excess electricity from the solar panel is supplied to the power grid. In another embodiment, when there is a shortage of electricity from the solar panel to maintain the temperature above the lower limit T1 and below the upper limit T2, electricity is supplied from the power grid.

[0015] In one embodiment, T1 is approximately 11.5 degrees Celsius, and T2 is approximately 12.5 degrees Celsius.

[0016] In an embodiment, during periods of high ambient temperatures (i.e., when the ambient temperature exceeds Tl), energy from the second energy source is used to cool the water in the tank towards the lower temperature Tl. The water temperature is then allowed to rise towards the upper temperature T2 when the second energy source no longer provides energy.

[0017] In another embodiment, during periods of low ambient temperatures (i.e., when the ambient temperature is below T2), energy from the second energy source is used to heat the water in the tank towards the upper temperature T2. The water temperature is then allowed to decrease towards the lower temperature Tl when the second energy source is insufficient.

[0018] In one embodiment, the aquaculture facility is a RAS facility.

[0019] In a second aspect, the present invention relates to a system for controlling energy in an aquaculture facility, characterized in that the facility comprises at least one closed tank with liquid and at least two energy sources. A first energy source, providing consistent energy, is primarily intended to supply energy to pumps, fans, control systems, and lights. A second energy source, providing intermittent energy, is designed for cooling or heating the water reservoir in the tank via a heat pump, which adjusts the cooling or heating to maintain the temperature in the tank above a predetermined lower temperature T1 and below an upper temperature T2.

[0020] In one embodiment The aquaculture facility includes marine organisms that produce variable energy through heterotrophic activity, influenced by the amount of feed and oxygen supplied.

[0021] In one embodiment, the energy supply to the water in the tank is adjusted based on the variable energy produced by the heterotrophic activity in the tank.

[0022] In one embodiment, the second energy source is a solar power system. In one embodiment, the first energy source is the power grid.

[0023] In one embodiment, the first energy source has backup in the form of a generator.

[0024] In one embodiment, excess electricity from the solar panels is supplied to the power grid. In one embodiment, in the case of insufficient electricity from the solar panels to maintain the temperature above the lower limit T1 and below the upper limit T2, electricity is supplied from the power grid.

[0025] In one embodiment, in the case of excess electricity from the solar panels, electricity is supplied back to the power grid. In one embodiment, T1 is approximately 11.5 degrees Celsius, and T2 is approximately 12.5 degrees Celsius.

[0026] In one embodiment, during periods of high ambient temperatures (i.e., when the ambient temperature exceeds Tl), energy from the second energy source is used to cool the water in the tank toward the lower temperature Tl. The water temperature is then allowed to rise towards the upper temperature T2 when the second energy source no longer supplies energy.

[0027] In another embodiment, during periods of low ambient temperatures (i.e., when the ambient temperature is below T2), energy from the second energy source is used to heat the water in the tank towards the upper temperature T2. The water temperature is then allowed to fall towards the lower temperature Tl when the second energy source does not supply sufficient energy.

[0028] In one embodiment, the aquaculture facility is a Recirculating Aquaculture System (RAS).

[0029] Description of Figures

[0030] Preferred embodiments of the invention are described in more detail below with reference to the accompanying figure, where: Figure 1 schematically shows an aquaculture facility, such as a RAS facility, operated with electricity from the power grid for functions requiring continuous power (e.g., pumps, fans, control systems), and where a solar panel powers a heat pump for cooling and heating the water in the tank.

[0031] Typically, energy demand is highest for cooling water, particularly in summer. Solar panels produce the most power during summer, making them suitable for cooling the water in the tank. In winter, there may be a need for heating under certain conditions, but the energy demand is generally lower compared to the cooling needs in summer.

[0032] Fish can typically tolerate daily temperature fluctuations of up to 1 degree without adverse effects on appetite and growth. This tolerance enables energy storage by cooling the water 0.5 degrees below the ideal temperature during the day when the sun shines and allowing the temperature to rise 0.5 degrees above the ideal temperature at night (when solar panels do not supply electricity).

[0033] Excess capacity for cooling can channel solar panel energy back to the power grid after metering. The advantage is nearly halving the power grid's energy demand.

[0034] Detailed Description of Preferred Embodiments Figure 1 schematically depicts a system using two energy sources (16, 18) to operate various processes in an aquaculture facility (10). The facility (10) comprises at least one tank (12) filled with liquid (14, water) for rearing marine organisms, such as fish. The tank (12) or tanks (12) contain significant amounts of water (14).

[0035] Fish in the water (14) require specific water temperatures to thrive and grow (often measured based on appetite and feed consumption). The optimal temperature depends on the fish species in the tank (12). However, it has been found that fish can tolerate some deviation in the water's temperature (14), typically (for salmonids) in the range of ±0.5 degrees Celsius.

[0036] The present invention seeks to exploit this tolerance for temperature variation to utilize an intermittent energy source (18), such as solar panels (18) or wind turbines. By using energy from such sources (18) to reduce or increase water temperature (14) as needed, the system allows temperature adjustments when intermittent energy sources (18) provide little or no energy (e.g., at night for solar panels or during calm periods for wind turbines).

[0037] Thus, energy from the intermittent energy source (18) is used to adjust the water temperature (14) in the tank (12) to ensure it stays within a range of T1 to T2, the lower and upper temperature limits tolerated by the specific fish in the tank (12).

[0038] This approach has been shown to reduce power grid demand by up to 50% (see example 1 below), resulting in significant cost savings. Energy generated by the intermittent energy source (18) is routed through a heat pump (21) for either heating or cooling the water (14) in the tank (12) in the aquaculture facility (10). The water circuit (120), marked with two boxes labeled 120, carries liquid between the heat pump (21) and the tank (12). Additionally, the units marked as (20) in Figure 1 represent the components that receive power for tank (12) processes.

[0039] As shown in Figure 1, the aquaculture facility (10) comprises at least two energy sources (16, 18). Electricity (16) from the power grid provides consistent energy, primarily for pumps, fans, control systems, and lights (20). All necessary energy from the intermittent energy source (18) is used to regulate the water temperature (14) in the tank (12). If there is excess energy from the intermittent source (18), it is fed back into the power grid, as shown with the dashed line (101) in Figure 1.

[0040] Optionally, backup energy can be provided by an emergency generator (22).

[0041] Example 1

[0042] Below, a preferred embodiment is described. It should be noted that the invention is not limited to this embodiment, and the scope of protection of the invention is defined by the patent claims.

[0043] Energy Consumption

[0044] Energy consumption in a Recirculating Aquaculture System (RAS) is crucial to understanding the energy required to maintain water temperatures while ensuring water quality stays within prescribed limits. The presented tank has a total water volume of 4500 m3. The body of water in which the fish are present is 2900 m3, with a feeding capacity of 2730 kg of feed per day. The biomass of 300,000 fish, each weighing 650 grams, totals 195,000 kg. They consume approximately 204 mg of oxygen per kg of fish per hour.

[0045] Contributors to Energy Affecting Water Temperature

[0046] Metabolism from Fish

[0047] Fish metabolism uses oxygen (O2) to convert feed into fish meat. A typical heat output from fish metabolism in a tank containing 195,000 kg of fish can be 101 kWh, as explained in the calculation below. This is referred to as "heterotrophic" energy produced by marine organisms in the aquaculture facility. Formula

[0048] Energy from Water Pumping

[0049] Energy used for water pumping is converted into heat. In optiRAS (the patent owner's RAS facility), very low pressure or lift height is required to circulate water. The main circulation pumps use about

[0050] 20 kW to circulate all the water in the fish water body in less than 15 minutes. Additionally, there are two more pumping stations in optiRAS. One pumps water to a mechanical filter, and another creates a circular water movement in the tank. These stations (mechanical filtering and flow pipes) together generate approximately 12 kW. This results in:

[0051] • Main circulation pump: 20 kW

[0052] • Mechanical filtering and flow pipes: 12 kW

[0053] • Total: 32 kW

[0054] Enthalpy

[0055] A significant contributor to heat in a RAS system is heat from condensation in the degassing process, especially relevant during summer under warm and humid conditions. By measuring the enthalpy of incoming and outgoing air in the degassing system, the energy added to the water can be calculated.

[0056] On a summer day at 30°C and 80% relative humidity, air enthalpy is about 98.25 kJ / m3.

[0057] After passing the air through the degasser and cooling to 12°C at 100% humidity, enthalpy is 42.05 kJ / m3.

[0058] This results in:

[0059] Incoming: 4 m3x98.25 kJ / m3=393 kJ4 \, \text{m}A3 \times 98.25 \, \text{kJ / m}A3 = 393 \, \text{kJ}

[0060] Outgoing: 4.8 m3x42.05 kJ / m3=201.84 kJ4.8 \, \text{m}A3 \times 42.05 \, \text{kJ / m}A3 = 201.84 \, \text{kJ}

[0061] Difference: 393 kJ-201.84 kJ=191.16 kJ / s=191 kW393 \, \text{kJ } - 201.84 \, \text{kJ} = 191.16 \, \text{kJ / s} \approx 191 \, \text{kW}.

[0062] Evaporation

[0063] A small cooling effect may occur from evaporation at the tank's water surface but is not included here.

[0064] New water Make-Up Water

[0065] Make-up water, used to remove accumulated nitrate, typically ranges from 3-600 liters per kg of feed. For 2730 kg of feed, this results in approximately 2730 kgx300 liters=819,000 liters / day2730 \, \text{kg} \times 300 \, \text{l iters} = 819,000 \, \text{l iters / day }. Energy input depends on whether the water is colder or warmer than the RAS water.

[0066] If intake water is 18°C, and the heat exchanger efficiency is 80%, the energy added is 48 kWh. In systems allowing the intake of cold water, this energy can become a cooling effect. Much of the energy can also be used directly to cool the RAS water.

[0067] Summary of Heat Development in Water

[0068] • Fish metabolism: 101 kW • Water pumping: 32 kW

[0069] • Enthalpy in degassing: 191 kW

[0070] • Make-up water: 48 kW

[0071] • Cooling via Aquaduct: -30 kW

[0072] • Total: 342 kW

[0073] Energy for pumping, operating the pumps, the fan machine, etc., for the facility is quite low for the optiRAS system

[0074] • Water pumping: 32 kW

[0075] Fan machine: (half contributes to water cooling) 60 kW Other pumps (e.g., intake): 10 kW

[0076] "This results in a requirement— needing 24 / 364 reliability in the supply— of approximately 102 kW.

[0077] Cooling requirements might reach 342 kW, but maintaining 4500 m3of water with 0.5°C temperature change takes about 7 hours at 342 kW. Typical heat generation in optiRAS averages 200 kW.

[0078] To maintain a daily variation within 1 degree, a cooling effect of approximately 400 kW applied to the water over 12 hours will be necessary. Subsequently, the temperature will drop to 11.5 degrees Celsius during the day with the 400 kW applied and rise to 12.5 degrees Celsius at night without cooling.

[0079] A tank with a 30 m diameter would require a 34x34 m building (1156 m2flat roof). Based on photovoltaic link (pvcalc) calculations for a 1100 m2 roof:

[0080] 400W panels requiring 2 m2each (550 panels) produce 220 kWp.

[0081] From May to September, this rulsults in approximately 4-5 kWh / kWp / day

[0082] This gives approximately 220 kWp x 4.5 kWh / kWp = 990 kWh.

[0083] 990 kWh / 12 = 82 kW in 12 hours.

[0084] With a heat pump with an efficiency of 3-5, this should provide 82 x 4 = 330 kW of cooling per day over 12 hours.

[0085] Conclusion

[0086] This solution is highly suitable for optiRAS.

Claims

Patent Claims1. A method for controlling energy in an aquaculture facility (10), characterized by the facility (10) comprising at least one closed tank (12) with water (14) and at least two energy sources (16, 18), where a first energy source (16) providing consistent energy is configured primarily to supply energy to pumps, fans, control systems, and lights (20), and a second energy source (18) providing intermittent energy is configured for cooling or heating the water (14) in the tank (12), wherein such cooling or heating of the water (14) in the tank (12) is carried out via a heat pump (21), where the intermittent second energy source (18) supplies energy and controls cooling or heating such that the temperature of the water (14) in the tank (12) stays above a first predetermined lower temperature T1 and below an upper predetermined temperature T2.

2. The method according to claim 1, characterized in that the aquaculture facility includes marine organisms providing variable energy through activity influenced by the amount of added feed and oxygen.

3. The method according to claim 2, characterized in that the energy supplied to the water (14) in the tank (12) is adjusted based on the amount of variable energy produced by the heterotrophic activity in the tank (12).

4. The method according to claim 1, characterized in that the second energy source (18) is a solar power system (18).

5. The method according to claim 1, characterized in that the first energy source (16) is the power grid (16).

6. The method according to claim 1, characterized in that the first energy source (16) includes backup in the form of a generator (22).

7. The method according to claim 1, characterized in that excess electricity from the solar panel (18) is supplied to the power grid (16).

8. The method according to claim 1, characterized in that when there is insufficient electricity from the solar panel (18) to maintain the temperature above the lower temperature T1 and below the upper temperature T2, electricity is supplied from the power grid (16).

9. The method according to claim 1, characterized in that T1 is approximately 11.5 degrees Celsius, and T2 is approximately 12.5 degrees Celsius.

10. The method according to claim 1, characterized in that during periods of high ambient temperatures, i.e., when the ambient temperature exceeds Tl, the energy from the second energy source (18) is used to cool the water (14) in the tank (12) towards the lower temperature Tl, allowing the water temperature (14) in the tank (12) to rise towards the upper temperature T2 when the second energy source (18) no longer supplies energy.

11. The method according to claim 1, characterized in that during periods of low ambient temperatures, i.e., when the ambient temperature is below T2, the energy from the second energy source (18) is used to heat the water (14) in the tank (12) up towards the upper temperature T2, allowing the water temperature (14) in the tank (12) to fall towards the lower temperature Tl when the second energy source (18) does not supply sufficient energy.

12. The method according to claim 1, characterized in that the aquaculture facility (10) is a Recirculating Aquaculture System (RAS) facility (10).

13. A system for controlling energy in an aquaculture facility (10), characterized by the facility (10) comprising at least one closed tank (12) with liquid (14) and at least two energy sources (16, 18), where a first energy source (16), delivering consistent energy, is primarily configured to supply energy to pumps, fans, control systems, and lights (20), and a second energy source (18), delivering intermittent energy, is configured for cooling or heating the water reservoir (14) in the tank (12). This cooling or heating of the water (14) in the tank (12) is carried out via a heat pump (21), with the intermittent second energy source (18) supplying energy and controlling cooling or heating so that the temperature in the tank (12) stays above a first predetermined lower temperature Tl and below an upper predetermined temperature T2.

14. The system according to claim 13, characterized by the aquaculture facility (10) including marine organisms providing variable energy through activity influenced by the amount of added feed and oxygen.

15. The system according to claim 14, characterized by the energy supplied to the water (14) in the tank (12) being adjusted based on the amount of variable energy produced by the heterotrophic activity in the tank (12).

16. The system according to claim 13, characterized in that the second energy source (18) is a solar power system (18).

17. The system according to claim 13, characterized in that the first source is the power grid (16).

18. The system according to claim 17, characterized in that the first energy source (16) has backup in the form of a generator (22).

19. The system according to 13, characterized in that excess electricity from the solar panel (18) is supplied to the power grid (16).

20. The system according to claim 13, characterized in that, in the event of insufficient electricity from the solar panel (18) to maintain the temperature above the lower temperature T1 and below the upper temperature T2, electricity is supplied from the power grid (16).

21. The system according to claim 13, characterized in that excess electricity from the solar panel (18), to maintain the temperature above the lower temperature T1 and below the upper temperature T2, is supplied to the power grid (16).

22. The system according to claim 13, characterized in that T1 is approximately 11.5 degrees Celsius, and T2 is approximately 12.5 degrees Celsius.

23. The system according to claim 13, characterized in that during periods of high ambient temperatures, i.e., when the ambient temperature exceeds Tl, the energy from the second energy source (18) is used to cool the water (14) in the tank (12) toward the lower temperature Tl, allowing the temperature of the water (14) in the tank (12) to rise toward the upper temperature T2 when the second energy source no longer supplies energy.

24. The system according to claim 13, characterized in that during periods of low ambient temperatures, i.e., when the ambient temperature is below T2, the energy from the second energy source (18) is used to heat the water (14) in the tank (12) up toward the upper temperature T2, allowing the temperature of the water (14) in the tank (12) to fall toward the lower temperature Tl when the second energy source (18) does not supply sufficient energy.

25. The system according to claim 11, characterized in that the system (10) is a RAS facility (10)

Images