Control of a hydrogen refueling station

Abstract

The invention related to a system for control of a hydrogen refueling station. The control of the hydrogen refueling station is optimized according to a high frequency tank profile in a time period between time A and time B. The high frequency tank profile includes selecting a first of the plurality of vessels as supply to the compressor during at least part of the refueling of the vehicle tank, the selection is based on pressure of hydrogen gas in one or more vessels of the supply storage. The control of the hydrogen refueling station is furthermore optimized according to a low frequency tank profile in a time period between time C and time D. The low frequency tank profile includes preparing one or more hydrogen refueling station components to enable a plurality of vehicle tank refuelings in the subsequent time period between time A and time B.

Claims

1. A system for control of a hydrogen refueling station, the hydrogen refueling station comprises components including a controller, a cooling system and a compressor fluidly connected to a supply storage and a dispenser, the supply storage comprises a plurality of vessels, wherein the controller is configured to facilitate control of a positon of a plurality of valves in fluid connections between the supply storage and the dispenser and thereby control of a flow of hydrogen gas from the supply storage to a tank of a vehicle, when the vehicle is connected to the dispenser, wherein the controller is further configured to optimize the hydrogen refueling station according to a high frequency tank profile in a time period between time A and time B, the high frequency tank profile includes selecting a first of the plurality of vessels as supply to the compressor during at least part of a refueling of the vehicle tank, the selection is based on pressure of hydrogen gas in one or more vessels of the supply storage, wherein the controller is further configured to optimize the hydrogen refueling station according to a low frequency tank profile in a time period between time C and time D, the low frequency tank profile includes preparing one or more of the hydrogen refueling station components to enable a plurality of vehicle tank refuelings in the subsequent time period between time A and time B, wherein the controller is further configured to determine the time A and the time B based on analysis of data from past refuelings acquired during a period of time of operation of the hydrogen refueling station, and wherein the controller is further configured to update the time A and the time B based on analysis of the data from past refuelings.

2. The system according to claim 1, wherein the low frequency tank profile includes selecting a first of the plurality of vessels having a pressure lower than a second of the plurality of vessels and perform a reload of hydrogen gas into the second vessel from the first vessel.

3. The system according to claim 1, wherein the cooling system includes a cooling bank, and wherein the low frequency tank profile includes optimizing the cooling capacity of the cooling bank.

4. The system according to claim 1, wherein the high frequency tank profile and the low frequency tank profile are mutually optimized to facilitate continuous operation of the compressor during a time period from time A to time D.

5. The system according to claim 1, wherein the wherein the controller is further configured to optimize control according to the high frequency tank profile simultaneously to refueling of the vehicle enables the compressor to reload a vessel of the supply storage or the cooling system to rebuild a cooling bank.

6. The system according to claim 1, wherein the controller is further configured to determine at least one of time C and time D based on information of past refuelings.

7. The system according to claim 1, wherein the energy consumption of the compressor per minute is higher when performing reload of pressure during a time period between a time C1 and a time D1 compared to reload of pressure performed in a time period between a time C2 and a time D2.

8. The system according to claim 1, wherein the controller is further configured to optimize control in the timer period between time A and time B further includes changing inlet pressure to the compressor by closing a valve associated with a first vessel of the supply storage thereby stopping flow of hydrogen from the first vessel to the compressor and opening a valve associated with a second vessel of the supply storage of the plurality of vessels of the supply storage thereby allowing flow of hydrogen from the second vessel to the compressor, wherein the change of inlet pressure is made when the pressure of hydrogen in the second vessel is higher than the pressure of hydrogen in the first vessel.

9. The system according to claim 1, wherein the controller is further configured to optimize control in the time period between time A and time B further includes that during refueling of the vehicle the operation speed of the compressor is varied.

10. The system according to claim 1, wherein after reaching a low pressure threshold of the first vessel of the supply storage, the reload of pressure of a second vessel of the supply storage continues by moving hydrogen gas from a third vessel of the supply storage having a pressure lower than the pressure of the second vessel either until a high reload pressure threshold is reached of the second vessel or a low reload pressure threshold of the third vessel is reached.

11. The system according to claim 1, wherein an early detection of the vehicle approaching the dispenser is provided.

12. The system according to claim 1, wherein the controller is controlling the operation speed of the compressor during based on a control strategy taking into account at least one of the list comprising: Noise reduction, Energy consumption, Cost of energy, Time until next expected time A, time B, time C and/or time D, Time until next delivery of gas, Ambient temperature and Refueling.

13. The system according to claim 1, wherein the controller is further configured to facilitate establishing an indication that an additional supply storage should be added to the supply storage of the hydrogen refueling station, based on average operation speed of the compressor.

14. The system according to claim 1, wherein the data from past refuelings comprises at least one of the following: number of refuelings, timestamp of each refueling, amount of hydrogen gas delivered to a vehicle, time it took to conduct the refueling, energy consumption.

15. The system according to claim 1, wherein the controller is further configured to optimize control in the time period between time A and time B further includes controlling the compressor to operate at a capacity above 100% of a rated capacity for a maximum 20 minutes.

16. The system according to claim 1, wherein the operation speed of the compressor is increased between time C and time D if a vehicle is attached to the dispenser.

Description

THE DRAWINGS

(1) For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts:

(2) FIG. 1 illustrates a hydrogen refueling station

(3) FIG. 2 illustrates a load pattern of a hydrogen refueling station over time.

DETAILED DESCRIPTION

(4) FIG. 1 illustrates an example of a hydrogen refueling station (HRS; Hydrogen Refueling Station) 1 according to the invention. The HRS 1 comprise a compressor 2, a dispenser 3, a controller 4, a supply storages 5 comprising a plurality of vessels (5a, 5b, 5c, . . . , 5n) and a cooling system 12. It should be mentioned, that the station 1 illustrated on FIG. 1 is only one example of such station. As long as there are at least two supply storages 5, a compressor 2 and a dispenser 3 any configuration of gas flow paths from supply storage 5 to dispenser can be referred to as a station 1 with respect to the present invention.

(5) The flow of hydrogen gas is preferably controlled by the controller 4 from the upstream supply storage 5 via valves 6 and fluid connection 7 downstream to the cooling system 12 and dispenser 3 to finally arrive at the vehicle 8. The flow of hydrogen may be controlled either through or bypassing the compressor 2, in both cases flow from a supply storage 5 to a vehicle 8 is referred to as a refueling. It is noted that FIG. 1 illustrates a plurality of valves 6, but to simplify the figure only a few reference numbers to these valves 6 is illustrated.

(6) Further, flow of hydrogen gas may also be controlled from a first vessel of the supply storages to a second vessel of the supply storages 5 either through or bypassing the compressor 2. These ways of reducing pressure in one vessel of the supply storage 5 to increase pressure in another vessel of the supply storage 5 are referred to reload of pressure (in a supply storage).

(7) Preferably the control of the compressor 2 is flexible i.e. the capacity of the compressor 2 is controlled depending on demand (real-time or future) of amount and or pressure of hydrogen gas.

(8) Flexible control of the compressor 2 can be obtained by adjusting the pressure of the supply storage 5 i.e. the inlet pressure of the compressor. A further parameter adding flexibility to the compressor control is the possibility of adjusting the compressor speed which is typically measured in revolutions per minute (RPM; Revolution Per Minute).

(9) The change of operation speed of the compressor 2 is preferably made by changing frequency of the voltage supply to the electric motor (not illustrated) driving the movable part (e.g. piston, not illustrated) of the compressor 2. This is preferably done by a frequency converter (not illustrated) so that when supplying voltage at nominal motor frequency to the motor, the compressor is operated at rated speed/capacity. Below the nominal frequency the operation speed is below the rated speed and above the nominal frequency the operation speed is above the rated speed. The exact level of the rated speed is determined by the design and choice of motor, compressor, etc.

(10) If a vehicle 8 is refueled from one and the same vessel of the supply storage 5 without making use of the compressor 2, the quantity and pressure of hydrogen gas in this vessel will be reduced and pressure equalization between the vessel and the vehicle tank will happen over time. Therefore, when pressure equalization is reached, the refueling can continue by shifting supply to the vehicle tank i.e. establish flow of hydrogen gas from another vessel having a higher pressure than the first. Such refueling without compressor will end when pressure equalization between the vessel of the supply storage 5 having the highest pressure and the vehicle tank is established.

(11) Typically, a refueling is conducted either by use of the compressor 2 during the entire refueling or in combination with refueling from one or more vessels of the supply storage 5.

(12) After a refueling where pressure is reduced in the supply storage 5, the inlet pressure to the compressor for the subsequent refueling is reduced leading to a less flexible compressor control for this subsequent refueling. This is at least true for the flexibility depending on the inlet pressure.

(13) To an extent, the reduction in flexibility can be avoided or postponed in time by using, more than one of the vessels of the supply storages 5 to the compressor 2. Therefore, during a refueling one or more supply storage shifts are made to obtain a pressure in the supply storages within preferred upper and lower pressure limits.

(14) Accordingly, it is desired to have as high pressure in the supply storages 5 as possible. Therefore, at least when the compressor 2 is not used in the refueling a vehicle 8, it can be used to move hydrogen gas from one vessel to another vessel of the supply storage 5. This moving of gas is in this document referred to as reload of gas.

(15) The flow of gas needed for the reload of gas and the refueling of vehicle 8 is preferably controlled by a single controller 4 which transmits control and measuring signals to and from valves 6, sensors 13 (pressure, temperature), compressor 2, dispenser 3, etc. To illustrate the communication of control signals (including wireless) are illustrated by dotted line 9 on FIG. 1, knowing that the control system of a HRS 1 is far more complex that what is illustrated. The measuring of flow, pressure and temperature in a HRS 1 is considered known by the skilled person and therefore not described in further details.

(16) The cooling system 12 preferably comprises a cooling bank 14 in the form of an element that can be cooled down to a given temperature and preferably kept at this temperature. Such element can be a block of aluminum or other metals, it may be solid state refrigerant of the cooling system 12 or some fluid that is solidified by the cooling system 12. The establishing of a cooling bank 14 is preferably made during a low frequency period 11, which is advantages in that during a subsequent high frequency period 10, the cooling capacity of the HRS 1 is higher than that of HRS 1 having cooling systems without a cooling bank 14. The control of the cooling system 12 optimised according to a low and high frequency tank profile has the same advantages as control of the compressor 2, the control according to a low and high frequency tank profile.

(17) The cooling system 12 is preferably a cooling as described in WO2016180425 hereby incorporated by reference.

(18) Reload of gas, refueling of vehicle tank, building of cooling bank 14 and thereby control of the compressor 2 is preferably controlled according to load pattern of the HRS 1. An example of a typical load pattern of a HRS 1 for a 24 hour period on a working day is illustrated on FIG. 2. The load pattern may vary a lot between different geographic locations, working days, holidays, weekends, if special events are arranged in the area of the HRS 1, etc.

(19) As noted, FIG. 1 includes a hydrogen supply connection 15. This connection point is used to supply hydrogen to the supply storage 5. As mentioned the supply storage 5 can be implemented as a removable storage e.g. in the form of a tube trailer(s) or container(s) which are intended to be replaced when empty or stationary storage i.e. vessels located above or below ground not intended to be moved when empty. The connection point 15 can also be supplied from an electrolysis apparatus located external to or as part of the HRS 1.

(20) On the timeline of FIG. 2 rush hours are illustrated between 6 in and 9 in the morning and again between 14 and 17 in the afternoon. Thurs, with reference to this particular nonlimiting example, at 6 in the morning a high frequency profile starts (i.e. at 6 a first time A is defined, referred to Ta1) and at 9 in the morning it ends (i.e. at 9 a first time B is defined, referred to as Tb1). In the same way, at 9 in the morning, a low frequency profile starts (i.e. at 9 a first time C is defined, referred to as Tc1) and at 14 in the afternoon it ends (i.e. at 14 a first time D is defined, referred to as Td1). The same definitions of start and stop of time periods are made with reference the second rush hour (second time A/Ta2−second time B/Tb2) and second low activity period (second time C/Tc2−second time D/Td2).

(21) Accordingly, it is noted that in the illustrated example the time of day where rush hour end and low activity period begins e.g. at first time B and first time C at 9 in the morning are referred to as both first time B and first time C. These first/second times A, B, C and D are in the this document simply referred to as time A, B, C and D.

(22) In the embodiment of the removable supply storage, the supply storage 5 is moved to hydrogen supply plant i.e. a larger plant storage or an electrolyer where the vessels 5a, 5b, 5c, 5n are filled up with hydrogen. Such hydrogen supply plant may receive a plurality of movable supply storages which needs to the filled up and returned to the hydrogen refueling stations 1.

(23) The control of this filling up of movable supply storages can be made similar to the reload of pressure described in relation to the supply storage 5 of the HRS 1. Even though the filling of the movable supply storages can be planned to a greater extent than refueling of vehicles, there will still be high frequency and low frequency periods at the hydrogen supply plant. Even if this is not the case, the considerations of energy consumption, energy price, etc. are also relevant to consider both in relation to produce the hydrogen but at least in relation to filling the movable supply storage.

(24) An example of a high frequency period could be the hours prior to truck drivers are to pick up the trailers. During such period, the compressor of the hydrogen supply plant is to be controlled so as to ensure all trailers are filled with hydrogen at the end of the period.

(25) The load pattern on the example illustrated on FIG. 2 illustrates two periods of high frequency of refuelings 10 and two periods of low frequency of refuelings 11. It should be mentioned, that as illustrated time A1 and time D2, time B1 and time C1, time A2 and time D1 and time B2 and time C2 respectively may be the same points in time.

(26) The high frequency periods are found between time A1 and time B1 and again between time A2 and time B2. From the time indications of the x axis, the high frequency refueling are in this example between 6 and 9 in the morning and again between 14 and 17 in the afternoon. In these periods, most people are driving to and from work and are likely to refuel their vehicles leading to a high frequency of refuelings at the HRS 1.

(27) The low frequency periods 11 are in this example found between time C1 and time D1 and again between time T2 and time D2 i.e. in between the high frequency periods 10. Hence typically the low frequency periods 11 are found to be around midday and during evening/night time.

(28) The high and low frequency periods 10, 11 can be defined by time of day, expectations to the number and distributions of refueling of the HRS 1. The value of control parameters of the software of the controller 4 can then be determined based on these expectations. It should be mentioned, that the load pattern may vary from one day to the next and from season to season.

(29) Another and preferred way of defining the high and low frequency periods 10, 11 is to analyze refuelings made at the HRS 1 after a period of time of operation of the HRS 1. Such period could cover one or more months where data of refueling are stored and analyzed. The data used for such analysis may include number of refuelings, timestamp of each refueling, amount of hydrogen gas delivered to the vehicle, time it took to conduct the refueling, energy consumption, etc. Data acquisition and the analysis (including averaging or normalizing of data) hereof may be continuously updated from day to day or from week to week.

(30) An example of analysis of the above-mentioned data is determining amount of gas delivered to vehicles over a period of time of e.g. 15 minutes at a specific week day (preferably all 24 hours of that day, length of periods is preferably between 1 and 120 minutes). Based on a comparison of deliveries during in this example 96 15 minutes periods the cut between the high and low frequency periods can be made. If the amount within a 15-minute period is above a threshold value, the period is part of a high frequency period 10. When the load of the HRS 1 has been analyzed over a period of e.g. 24 hours, the high frequency periods 10 can be defined. When having defined the high frequency periods 10, the low frequency periods 11 may simply be defined as the periods between the high frequency periods 10.

(31) The value of the threshold between high and low frequency periods can be determined based on the relative difference between amounts delivered and/or energy consumption and/or available amount of gas in the supply storages in the 15 minutes periods of the above example.

(32) Accordingly, now the control of the compressor 2 and cooling system 12 can be made intelligent e.g. based on expected future needs. The overall control strategy of the high frequency period 10 is obviously to ensure fast refueling and with any available capacity of compressor 2 increase pressure in the supply storage 5. During this period of time, the compressor 2 and cooling system 12 are controlled according to a so-called high frequency tank profile. The overall control strategy of the low frequency period 11 is to perform pressure reload of vessels of the supply storages 5, built cooling bank 14 of the cooling system 12 and to avoid too many start/stop sequences of the compressor 2. During this period of time the compressor 2 and the cooling system 12 is controlled according to a so-called low frequency tank profile.

(33) The main object of the high frequency tank profile is to facilitate as many refueling as fast as possible. This may include using the compressor to increase pressure from a storage supply 5 and move it to a vehicle tank. Further, it may include operating the compressor 2 to increase the pressure in one vessel of the supply storage 5 at the expense of another one of the vessels of the supply storages 5. Further, it may include operating the cooling system 12 to try to maintain the cooling bank 14 and/or cool the hydrogen gas as its flow towards the dispenser 3. Further and preferably, it may include a combination hereof.

(34) The high frequency tank profile may be subject to local restrictions such as a maximum (or minimum) power consumption (within a given period of time), maximum noise emission and the like. Therefore, even if compressor/cooling capacity is available, it may not be utilities e.g. due to noise restrictions.

(35) On the other hand, the compressor 2 may be operated above its maximum rated capacity (/speed) for a period of time. By having a compressor 2 that is able to be operated in this way, the peak capacity of the HRS 1 is increased thereby allowing to reduce the size or number of supply storages 5. Alternatively, the size of the compressor 2 can be reduce if it is possible to operated it above its rated capacity for a period of time. Both of these alternatives are leading to a reduced cost of capacity of the HRS 1 in that the capacity of the one or more supply storages 5 can be reduce while maintaining the overall capacity of the HRS 1.

(36) The ability of varying the capacity of the compressor 2 is facilitated by providing as high inlet pressure to the compressor as possible and/or by increase the operating speed of the compressor.

(37) The first, i.e. facilitate high inlet pressure, is obtained by ensuring high pressure in the supply storages. This can be obtained by ensuring timely replenishing of the individual storages 5 and perform pressure reload in-between refueling in the high frequency period 10 and/or during the low frequency period 11.

(38) The latter, i.e. varying the operation speed of the compressor is done depending on the type of compressor 2. In the case the compressor is driven by an electric motor, the operation speed can be controlled by regulating the frequency of the voltage supplied to the compressor 2. Hence, what in this document is referred to as rated capacity of the compressor is obtained at a nominal frequency of the motor driving the compressor. Accordingly, a 50 Hz motor operates the compressor at rated speed or capacity when supplied with a voltage having a frequency of 50 Hz. Likewise, a 60 Hz motor operates the compressor at rated speed or capacity when supplied with a voltage having a frequency of 60 Hz. The speed of the compressor refers to frequency of movement of the diaphragm in a diaphragm compressor or piston cycles.

(39) The varying of the operation speed i.e. in this example adjusting the frequency of voltage to the motor driving the compressor may include controlling the compressor above (and below) its rated capacity for a period of time i.e. the frequency to the motor is above (or below) 50 Hz/60 Hz for a 50 Hz/60 Hz motor.

(40) According to an embodiment, it may be possible to increase the operation speed to a speed of up to and above 900 rmp (of piston in the compressor) for a limited period of time less than 10 minutes. This however requires a special type of compressor 2. Such compressor 2 is preferably a diaphragm compressor as described in WO2016184468, hereby incorporated by reference.

(41) Operating the compressor above rated capacity is advantages in that it has the effect that this increases the capacity of the HRS 1 i.e. with the same supply storage the HRS 1 is able to deliver hydrogen gas with a higher pressure than a HRS 1 having a compressor only capable to operate its compressor at rated capacity. Further it has the effect that the refueling time (and time of reload of pressure in the supply storage) can be reduced due to the higher pressure with is possible to establish. Despite the higher level of noise and energy consumption, this is desirable when there is a current need for the compressor to deliver high pressure.

(42) The operation of the compressor 2 below rated capacity i.e. with voltage supplied to the motor driving the compressor below nominal frequency of the motor is of course also possible. However, this is mainly used under control in the low frequency periods as will be described below. Advantages of operating the compressor below rated capacity includes at least lower energy consumption and low noise emission. This is desirable when there is no current need for the compressor to deliver high pressure.

(43) When mentioning the compressor in this document preferably a reference is made to a diaphragm compressor. The diaphragm compressor may be of the type having an elongated or oblong shaped compression chamber. However, it should be mentioned, that other types of compressors could be used and also these other types may be controlled above or below their rated capacity. Other types of compressors such as ionic-liquid and piston compressors could be used.

(44) Further it should be mentioned, that the compressor may be a multi stage compressor preferably with at least two stages. This is advantages in that the compressor is able to perform a first compression of gas to a first stage to a first pressure and a subsequently compression of gas at a second stage to a second pressure and thereby increase efficiency of the high-pressure compressor.

(45) The high frequency tank profile is therefore often developed to, or by means of control parameters of the control software of the controller 4 of the HRS 1 adjusted to, operated optimal at a specific site. Especially with respect to requirements to amount and temperature of gas that has to be delivered and noise made and energy used in the high frequency periods. Therefore, the high frequency tank profile is developed as a tradeoff between capacity in the vessels of the supply storage 5, cooling capacity of the cooling system 12, local requirements and required amount of hydrogen gas delivered to the users of the HRS 1 which typically would be vehicle owners.

(46) The main object of the low frequency tank profile is to facilitate reload of the supply storage 5 and rebuilt of cooling bank 14 as efficient as possible to be ready for the refueling of hydrogen of the following high frequency period. A secondary object can be to keep the compressor running continuously. Another secondary object can be to use excess energy of the utility grid and convert it to pressurized hydrogen gas in the supply storage of the HRS 1.

(47) As with the high frequency tank profile, the low frequency tank profile may also be subject to local requirements especial when used at night time. One example could be if the HRS 1 is located inside a city limit, then restrictions to noise would be expected at least during night time.

(48) The reload of supply storage and/or establishing of cooling bank 14 during the low frequency tank profile is preferably controlled by adjusting parameters of the control software executed by the controller 4 and/or based on analysis of amount of hydrogen available in the individual supply storages 5, remaining time of the low frequency period, etc. This is leading to an operation speed of the compressor 2 which is lower than during the high frequency period.

(49) The result of an optimized control of the compressor 2 and/or cooling system 12 during the low frequency period, is that the end of this period (the beginning of the subsequent high frequency period) the pressure of the vessels of the supply storage 5 are as desired, the cooling capacity of the cooling bank 14 is as desired (preferably maximum) and that this is obtained with as little energy consumption from the compressor 2 and/or cooling system 12 as possible.

(50) Accordingly, optimized control during a period i.e. the high or low frequency tank profiles control strategies should be understood as control preparing components of the HRS 1 to the subsequent time period where the control of the HRS 1 is made with reference to the opposite control strategy. This includes as mentioned increasing/lowering pressure in a supply storage as fast/energy efficient as possible, built up cooling capacity, etc.

(51) Desired pressure of the supply storages 5 at the end of the low frequency period to facilitate refuelings is preferably between 0 and 1000 bar. For vessels of the supply storage ready to be used as supply to the compressor for refueling the pressure of the vessels may be from 100 to 1000 bar (with intervals between of 50 bar), preferably 200, 350, 450, 500 and 950 bar. For vessels for the supply storage ready to be refilled or swapped the pressure may be below 100 bar, preferably below 50 bar.

(52) The analysis of need of pressure and/or cooling capacity is preferably updated if during the low frequency period a refueling is made. Such refueling reduced the pressure of the supply storages 5 and therefore the speed of the compressor needs to be updated (increased) to end at the desired pressure of the supply storage 5 at the end of the low frequency period.

(53) It is preferred that the compressor do not stop during the low frequency period (nor during the high frequency period) in that typically compressors are design for continuous operation opposite to a plurality of start/stops. However, stopping and subsequently starting the compressor 2 is possible, however not desired.

(54) It should be mentioned that operation during the low frequency period between time B1 and time D1, the operation speed is higher than in the low frequency period between time C2 and time D2. This is because, the time to nest expected refueling is expected to be shorter between time C1/D1 than between time C2/D2.

(55) For control both according to the high and low frequency tank profile, it is desired to have early detection of a vehicle approaching the HRS 1 to get a refueling. Early detection may be implemented by sensors located at the HRS 1 or close thereby, GPS of vehicle or smartphone of vehicle driver or the like.

(56) The early detection signal can be used to increase speed of the compressor 2 and the operation of the cooling system 12 and thereby ensuring as fast refueling as possible. It is however especially advantages when control is performed according to the low frequency tank profile in that here typically the compressor would operate in relatively low operation speed and hence an increase of speed is needed to use the compressor during the refueling.

(57) For both profiles, the control software may be the same but with different parameters settings. The parameter setting may relate to one or more of the lists comprising: Noise reduction, temperature (ambient or of a component), Energy consumption, Cost of energy, Time until next expected refueling, Time until next expected time A, time B, time C and/or time D, Time until next delivery, and/or Pressure in one for the plurality of supply storages. Requirements to noise is typically determined locally and depends on if an area is defined as industry or residential if it is day or night. As an example, requirements e.g. for Germany can be found in the so-called TA lärm instruction.

(58) The mutual optimization of the tank profiles should be understood such that the control of the compressor 2 and cooling system 12 during time period A to B (high frequency tank profile) is made at least partly based on the expected control of the compressor 2 and cooling system 12 in the subsequent time period between time C and time D (low frequency tank profile) and vice versa. As an example, could be mentioned, that between refueling in the high frequency tank profile, the compressor 2 can perform reload of a supply storage 5 and the cooling system 12 rebuilt cooling bank 14. The speed of the reload and thereby of the compressor can be determined e.g. by requirements to noise and energy consumption, but also to the length of time remaining in period between time A and B or the time between subsequent time period C to D, the level of hydrogen in the supply storage having the lowest pressure, etc.

(59) Likewise, the control of the compressor during time period time C and time D is preferably controlled either according to a supply storage pressure desired at the beginning of the subsequent time period between time A and time B and/or the time of the day of the next delivery of hydrogen gas. Both are important to have as efficient a HRS control system as possible.

(60) In fact, instead of controlling the compressor 2 according to a specific time for delivery of gas to the HRS, the control system of the HRS 1 is able to estimate when the supply storage is ready to be refilled or swapped (commonly referred to as delivery of hydrogen) and provide this information to a logistics center in charge of refueling of gas at the HRS 1.

(61) It should be mentioned, that it is possible to reduce the compressor speed towards the end of a refueling. By doing so the flow of hydrogen gas is reduce and thereby when finally terminating the flow by closing a valve, the mechanical stress is reduced if the flow is reduced before closing the valve.

(62) It should be mentioned, that it is possible to temporary stop cooling or reduce threshold temperature of flow line 7 between the cooling system 12 and the dispenser 3. The distance here between may be 50 meters or more and when no refuelings are expected (in the low frequency period) energy can be saved on allowing a higher temperature of this line. In relation early warning, this would also be advantages in that desired temperature of the hydrogen gas at the dispenser 3 can be obtained faster if cooling of the line 7 between cooling system 12 and dispenser 3 can be made prior to the vehicle 8 is connected to the dispenser 3.

(63) Reference to a supply storage is made to a plurality of individual vessels or one or more vessels having internal banks facilitating holding hydrogen gas separated at different pressures. The size or number of vessels or banks of a supply storage is determined by the capacity desired for the HRS 1 to have. The higher capacity, the larger supply storage 5.

(64) Typically, the supply storage 5 is refilled from a truck trailer, but a swap of supply storage 5 of the HRS with a prefilled new supply storage 5 is also possible. The latter is advantages in that it reduces time to deliver gas in that the new supply storage is filled at the electrolyser site and not on the HRS site.

(65) The maximum pressures of the vessels of the supply storage 2 may vary from 200 bar to 1000 bar. Typically, only one or two vessels have rated pressure up to or above 1000 bar in that such vessels are more expensive than lower pressure vessels. However, high-pressure vessels are desired in that by having these, fast refueling can be initiated without having the compressor up and running.

(66) As an example, a supply storage 5 of or connected to a HRS 1 may include low, medium and high-pressure vessels. According to such example the supply storage 5 could comprise 20 or more low pressure vessels having a rated pressure between 100 and 300 bar, preferably 200 bar. Further, 20 or more medium pressure vessels having a rated pressure between 300 and 550 bar, preferably 450 bar and further, 20 or more high pressure vessels having a rated pressure between 500 and 1200 bar, preferably 950 bar.

(67) The number and type (1, 2, 3 or 4) of vessels is determined by one or more of the following capacities of the HRS 1, the volume of the individual vessel, maximum footprint of the HRS, etc. Sometimes, medium and high-pressure vessels are referred to as fueling storage.

(68) From the above it is now clear that this document relates to a control of a gas refueling station, preferably a hydrogen gas refueling station. The control is optimized over a period of e.g. 24 hours to be as efficient as possible. Therefore, the time period is divided into one or more high and low frequency periods. In the low frequency periods, the components of the refueling station is prepared for the subsequent high frequency period. This may include establishing reload of pressure in vessels of the supply storage, emptying a vessel of the supply storage 5 and establishing a cooling bank 14 in the cooling system. By doing so in a low frequency period e.g. during night time, it may be done as energy and noise efficient as possible. It is advantages in that during the following high frequency period, the refueling station is as prepared as possible to as efficient as possible handle a plurality of refuelings within a period of a few hours. The definition of low and high frequency periods and how to control compressor and cooling system herein is described above.

(69) Further it is clear, that also when filling movable supply storages at a hydrogen supply plant, the control hereof can be made as the above described reload of supply storage 5 of the HRS 1. Also, it is clear, that from the control of the valves 6 of FIG. 1 flow of hydrogen from supply to the hydrogen supply connection 15 and/or the supply storage 5 to the vehicle and/or to reload of supply storage vessels 5a, 5b, 5c, 5n can be made in many different ways depending on position of the valves.

LIST

(70) 1. Hydrogen refueling station 2. Compressor 3. Dispenser 4. Controller 5. Supply storage 6. Valves 7. Fluid connection 8. Vehicle 9. Electric connection 10. High frequency period 11. Low frequency period 12. Cooling system 13. Sensors (pressure and/or temperature) 14. Cooling bank 15. Hydrogen supply connection